Universal Mechanism UM Input Program Engineering Simulation Software User's manual

UNIVERSAL MECHANISM 7.0
UM Input Program
User’s manual
2014
General methods of development of UM models are considered. Features in description of images,
bodies, joints, force elements and so on are discussed
Universal Mechanism 7.0
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Chapter 3. Data input program
Contents
3. UM INPUT PROGRAM ......................................................................................................................... 3-7
3.1. WHAT’S NEW IN 7.0? ............................................................................................................ 3-7
3.2. DATA INPUT PROGRAM: GENERAL INFORMATION............................................................... 3-7
3.3. OPTIONS OF INPUT PROGRAM .............................................................................................. 3-8
3.3.1. General options of the Input program ......................................................................................................... 3-8
3.3.2. Setup of symbolic generation of equations of motion ................................................................................. 3-9
3.3.2.1. Delphi ................................................................................................................................................ 3-10
3.3.2.2. C++ .................................................................................................................................................... 3-10
3.3.3. Paths to external subsystems ..................................................................................................................... 3-12
3.3.4. Paths to user’s files ................................................................................................................................... 3-13
3.3.5. Path to CADlook program ........................................................................................................................ 3-13
3.3.6. Component libraries .................................................................................................................................. 3-14
3.4. MAIN MENU COMMANDS AND TOOL PANEL ....................................................................... 3-15
3.4.1. File ............................................................................................................................................................ 3-15
3.4.2. Edit ............................................................................................................................................................ 3-16
3.4.3. Object ........................................................................................................................................................ 3-16
3.4.4. Add ........................................................................................................................................................... 3-17
3.4.5. Tools ......................................................................................................................................................... 3-17
3.4.6. Help........................................................................................................................................................... 3-18
3.4.7. Tool panel ................................................................................................................................................. 3-19
3.5. OBJECT CONSTRUCTOR ...................................................................................................... 3-20
3.5.1. Basic elements of constructor ................................................................................................................... 3-20
3.5.1.1. Tree of elements ................................................................................................................................ 3-21
3.5.1.2. Animation window ............................................................................................................................ 3-23
3.5.1.2.1. Visualization of object elements ................................................................................................. 3-23
3.5.1.2.2. Modes of animation window ...................................................................................................... 3-23
3.5.1.2.3. Basic system of coordinates, pop-up menu ................................................................................ 3-25
3.5.1.2.4. Tool bar ...................................................................................................................................... 3-26
3.5.1.2.5. Additional possibilities for object translation/rotation by mouse ............................................... 3-27
3.5.2. Data inspector and some features of object element description .............................................................. 3-28
3.5.2.1. Object parameters and options ........................................................................................................... 3-28
3.5.2.1.1. “General” tab .............................................................................................................................. 3-28
3.5.2.1.2. “Option” tab ............................................................................................................................... 3-29
3.5.2.1.3. “Sensors/LSC” tab ...................................................................................................................... 3-30
3.5.2.1.4. “Variables” tab ........................................................................................................................... 3-31
3.5.2.1.5. “Curves” tab ............................................................................................................................... 3-32
3.5.2.1.6. “Attributes” tab ........................................................................................................................... 3-32
3.5.2.2. Lists of elements of a definite type .................................................................................................... 3-33
3.5.2.3. Auxiliary tabs in inspector ................................................................................................................. 3-34
3.5.2.3.1. External connections .................................................................................................................. 3-34
3.5.2.3.2. Indices ........................................................................................................................................ 3-34
3.5.2.3.3. Summary .................................................................................................................................... 3-35
3.5.2.3.4. Coordinates ................................................................................................................................. 3-35
3.5.2.4. Data types .......................................................................................................................................... 3-37
3.5.2.4.1. Numeric constants ...................................................................................................................... 3-37
3.5.2.4.2. Identifiers.................................................................................................................................... 3-37
3.5.2.4.3. Standard functions and constants................................................................................................ 3-39
3.5.2.4.4. Function bodyinertia – inertia parameters .................................................................................. 3-40
3.5.2.4.5. Constant symbolic expressions ................................................................................................... 3-42
3.5.2.4.6. Expression – explicit function .................................................................................................... 3-42
3.5.2.4.6.1. Function of time - t.............................................................................................................. 3-42
3.5.2.4.6.2. Scalar force and torques of the Expression type: x, v, t ..................................................... 3-43
3.5.2.4.6.3. Curves as expressions ......................................................................................................... 3-43
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Chapter 3. Data input program
3.5.2.4.6.4. Functions of description of parametrical graphic elements ................................................. 3-43
3.5.2.4.6.5. Z –surfaces .......................................................................................................................... 3-44
3.5.2.4.7. Kinematic functions .................................................................................................................... 3-44
3.5.2.4.7.1. Function coordinate ............................................................................................................. 3-45
3.5.2.4.7.2. Functions dm, dx, dy, dz ..................................................................................................... 3-46
3.5.2.4.7.3. Functions vm, vx, vy, vz, vr ................................................................................................ 3-47
3.5.2.4.7.4. Functions ax, ay, az ............................................................................................................. 3-48
3.5.2.4.7.5. Function angle ..................................................................................................................... 3-49
3.5.2.4.7.6. Functions yaw, pitch, roll .................................................................................................... 3-50
3.5.2.4.7.7. Functions psi, theta, phi (Euler angles) ............................................................................... 3-51
3.5.2.4.7.8. Functions wm, wx, wy, wz .................................................................................................. 3-51
3.5.2.4.7.9. Function incang ................................................................................................................... 3-52
3.5.2.4.7.10. Functions accm, accx, accy, accz ...................................................................................... 3-53
3.5.2.4.7.11. Functions wdtm, wdtx, wdty, wdtz ................................................................................... 3-53
3.5.2.4.8. List of variables .......................................................................................................................... 3-55
3.5.2.4.9. Integral function and adding differential equations .................................................................... 3-56
3.5.2.4.10. External functions ..................................................................................................................... 3-57
3.5.2.4.11. Time function using text file .................................................................................................... 3-59
3.5.2.4.12. Timetable as a method of description of time functions ........................................................... 3-61
3.5.2.4.13. Expression editor ...................................................................................................................... 3-62
3.5.3. List of identifiers ....................................................................................................................................... 3-64
3.5.3.1. Window with list of identifiers .......................................................................................................... 3-64
3.5.3.2. Modification of identifiers ................................................................................................................. 3-64
3.5.3.3. Identifier sheets .................................................................................................................................. 3-65
3.5.3.4. Object refresh after change of identifier value ................................................................................... 3-66
3.5.3.5. Pop-up menu of identifier list ............................................................................................................ 3-66
3.5.3.6. Adding new identifiers by element description ................................................................................. 3-68
3.5.3.7. Jump to identifier from the element parameter .................................................................................. 3-69
3.5.4. 2D curve editor ......................................................................................................................................... 3-70
3.5.4.1. Modes of curve editor ........................................................................................................................ 3-70
3.5.4.2. Tool bar.............................................................................................................................................. 3-70
3.5.4.3. Adding, positioning, and deleting separate point on a curve ............................................................. 3-71
3.5.4.4. Selecting, copying, deleting and moving fragments and curves ........................................................ 3-72
3.5.4.5. Closing curve ..................................................................................................................................... 3-73
3.5.4.6. Smoothing .......................................................................................................................................... 3-73
3.5.4.7. Using the clipboard for creating curves and functions ....................................................................... 3-73
3.5.5. Hot keys .................................................................................................................................................... 3-74
3.5.5.1. Constructor hot keys .......................................................................................................................... 3-74
3.5.5.2. Inspector hot keys .............................................................................................................................. 3-74
3.5.5.3. Animation window hot keys .............................................................................................................. 3-74
3.5.5.4. Inspector tab with a list ...................................................................................................................... 3-74
3.6. DATA INPUT ........................................................................................................................ 3-76
3.6.1. Data Input Sequence ................................................................................................................................. 3-76
3.6.2. Methods for adding elements to object ..................................................................................................... 3-77
3.6.2.1. Direct creation of single element ....................................................................................................... 3-77
3.6.2.2. Adding elements by visual components ............................................................................................ 3-77
3.6.2.3. Main menu commands for adding a typed element ........................................................................... 3-77
3.6.2.4. Adding typed elements by pop-up menu of element tree................................................................... 3-78
3.6.2.5. Insert of element from other model by clipboard............................................................................... 3-78
3.6.2.6. Insert of element from other model by file ........................................................................................ 3-78
3.6.2.7. Merging models ................................................................................................................................. 3-79
3.6.3. Subsystems................................................................................................................................................ 3-80
3.6.3.1. Adding a subsystem ........................................................................................................................... 3-80
3.6.3.2. Transformation of model into subsystem........................................................................................... 3-82
3.6.3.3. Interconnection of subsystem. Use of external elements ................................................................... 3-82
3.6.3.3.1. External elements. Autodetection ............................................................................................... 3-82
3.6.3.3.2. Assignment of second bodies to external elements .................................................................... 3-83
3.6.3.3.3. Using fictitious body instead of external elements ..................................................................... 3-85
3.6.4. Standard interface for setting local system of coordinates ........................................................................ 3-87
3.6.5. Assigning Graphical Image to Object Element ......................................................................................... 3-89
3.6.6. Assignment of graphic images to rods, linear and bipolar force elements ................................................ 3-90
3.6.7. Input of 3D curves .................................................................................................................................... 3-92
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Chapter 3. Data input program
3.6.7.1. Adding new curve .............................................................................................................................. 3-93
3.6.7.2. Setting curves by analytic expressions .............................................................................................. 3-96
3.6.7.3. Setting curves by 2D points ............................................................................................................... 3-97
3.6.7.4. Setting curves by 3D points. B-spline................................................................................................ 3-98
3.6.8. Input of Graphical Objects ...................................................................................................................... 3-103
3.6.8.1. Lists of Graphical Objects and Graphical Elements ........................................................................ 3-103
3.6.8.2. Input of graphical elements (GE) ..................................................................................................... 3-106
3.6.8.2.1. Polyhedron................................................................................................................................ 3-106
3.6.8.2.2. Ellipse ....................................................................................................................................... 3-107
3.6.8.2.3. Box ........................................................................................................................................... 3-108
3.6.8.2.4. Spiral ........................................................................................................................................ 3-109
3.6.8.2.5. Ellipsoid.................................................................................................................................... 3-110
3.6.8.2.6. Cone ......................................................................................................................................... 3-111
3.6.8.2.7. Parametrical GE........................................................................................................................ 3-112
3.6.8.2.8. Profiled GE ............................................................................................................................... 3-114
3.6.8.2.9. Z-surface ................................................................................................................................... 3-118
3.6.8.2.10. Spring ..................................................................................................................................... 3-120
3.6.8.2.11. Link ........................................................................................................................................ 3-121
3.6.8.2.12. Plate ........................................................................................................................................ 3-121
3.6.8.2.13. GO as a graphic element ......................................................................................................... 3-122
3.6.8.2.14. Graphic element ASC imported from CAD program ............................................................. 3-124
3.6.8.3. GE colors ......................................................................................................................................... 3-127
3.6.8.4. Position and Orientation of GE ........................................................................................................ 3-128
3.6.8.5. Inertia parameters of GE .................................................................................................................. 3-129
3.6.8.6. Curve editor ..................................................................................................................................... 3-130
3.6.9. Describing rigid bodies ........................................................................................................................... 3-133
3.6.9.1. Image and visualization of a body. Body-fixed SC ......................................................................... 3-134
3.6.9.1.1. Assignment of an image to body .............................................................................................. 3-134
3.6.9.1.2. Modes of animation window and body image .......................................................................... 3-134
3.6.9.1.3. Modes of body image ............................................................................................................... 3-135
3.6.9.1.3.1. Invisibility of body ............................................................................................................ 3-135
3.6.9.1.3.2. Wired body mode .............................................................................................................. 3-136
3.6.9.1.4. Reassignment of body image in simulation program ............................................................... 3-137
3.6.9.2. Inertia parameters ............................................................................................................................ 3-138
3.6.9.3. Internal (hidden) body joint ............................................................................................................. 3-141
3.6.9.4. Position tab ...................................................................................................................................... 3-143
3.6.9.5. Rapid access to elements connected with body ............................................................................... 3-143
3.6.9.6. Connection points ............................................................................................................................ 3-144
3.6.9.6.1. Adding general connection points ............................................................................................ 3-145
3.6.9.6.2. Adding oriented connection points ........................................................................................... 3-146
3.6.9.6.3. Adding vectors ......................................................................................................................... 3-148
3.6.9.7. Body «Ground» ............................................................................................................................... 3-148
3.6.9.8. 3D Contact ....................................................................................................................................... 3-150
3.6.10. Joints and force elements: some features of description ....................................................................... 3-154
3.6.10.1. Assignment of bodies..................................................................................................................... 3-154
3.6.10.2. Type of element ............................................................................................................................. 3-154
3.6.10.3. Attachment points .......................................................................................................................... 3-155
3.6.10.4. Visual assignment of bodies and attachment points ...................................................................... 3-155
3.6.10.5. Autodetection ................................................................................................................................. 3-155
3.6.10.6. Transformation of coordinates ....................................................................................................... 3-156
3.6.11. Input of joints ........................................................................................................................................ 3-157
3.6.11.1. Visualization of joints .................................................................................................................... 3-157
3.6.11.2. Weight of joint ............................................................................................................................... 3-157
3.6.11.3. Conversion of joint type ................................................................................................................ 3-157
3.6.11.4. Status of joint ................................................................................................................................. 3-158
3.6.11.4.1. Joint in tree and cut joint. Closure of cut joints ...................................................................... 3-158
3.6.11.4.2. Removed joint ........................................................................................................................ 3-161
3.6.11.4.3. Fixation joint .......................................................................................................................... 3-162
3.6.11.4.4. Joint with negative direction................................................................................................... 3-162
3.6.11.5. Input of rotational and translational joints ..................................................................................... 3-164
3.6.11.6. Input of 6 d.o.f. joint ...................................................................................................................... 3-167
3.6.11.7. Input of joint of generalized type ................................................................................................... 3-169
3.6.11.7.1. Elementary transformation tc ................................................................................................. 3-170
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Chapter 3. Data input program
3.6.11.7.2. Elementary transformation rc ................................................................................................. 3-170
3.6.11.7.3. Elementary transformations tv, rv .......................................................................................... 3-170
3.6.11.7.4. Elementary transformations tt, rt ............................................................................................ 3-171
3.6.11.8. Input of quaternion joint ................................................................................................................ 3-172
3.6.11.9. Input of rod constraint.................................................................................................................... 3-173
3.6.11.10. Input of mates .............................................................................................................................. 3-174
3.6.11.11. Input of convel (CV) joint ........................................................................................................... 3-176
3.6.12. Input of force elements ......................................................................................................................... 3-177
3.6.12.1. Input of gravity .............................................................................................................................. 3-177
3.6.12.2. Description of scalar force and torque ........................................................................................... 3-178
3.6.12.2.1. Linear force element ............................................................................................................... 3-179
3.6.12.2.2. Friction and elastic-frictional elements .................................................................................. 3-180
3.6.12.2.3. Elastic-frictional element 2 ..................................................................................................... 3-181
3.6.12.2.4. Viscous-elastic element .......................................................................................................... 3-182
3.6.12.2.5. Nonlinear viscous-elastic element .......................................................................................... 3-183
3.6.12.2.6. Points (numbers) ..................................................................................................................... 3-185
3.6.12.2.6.1. Force dependence on x, v, t ............................................................................................. 3-185
3.6.12.2.6.2. Indicator diagram ............................................................................................................ 3-188
3.6.12.2.7. Points (expressions) ................................................................................................................ 3-189
3.6.12.2.8. External function .................................................................................................................... 3-190
3.6.12.2.9. Expression .............................................................................................................................. 3-191
3.6.12.2.10. List of characteristics ............................................................................................................ 3-192
3.6.12.2.11. Fancher leaf spring ............................................................................................................... 3-193
3.6.12.2.12. Hysteresis ............................................................................................................................. 3-194
3.6.12.2.13. Impact (bump stop)............................................................................................................... 3-196
3.6.12.2.14. Ratchet .................................................................................................................................. 3-197
3.6.12.2.15. Library DLL ......................................................................................................................... 3-198
3.6.12.2.16. List of forces ......................................................................................................................... 3-198
3.6.12.3. Input of bipolar force elements ...................................................................................................... 3-199
3.6.12.4. Input of scalar torque force element .............................................................................................. 3-200
3.6.12.5. Input of generalized linear force elements ..................................................................................... 3-202
3.6.12.5.1. General information on generalized linear force elements ..................................................... 3-202
3.6.12.5.2. Some features of description of elastic element ..................................................................... 3-203
3.6.12.5.3. Bilinear force element ............................................................................................................ 3-204
3.6.12.6. Input of contact force elements ...................................................................................................... 3-205
3.6.12.6.1. Coefficient of friction, stiffness, damping at contact .............................................................. 3-205
3.6.12.6.2. Points-Plane contact ............................................................................................................... 3-207
3.6.12.6.2.1. Contact geometry ............................................................................................................ 3-207
3.6.12.6.2.2. Close contact ................................................................................................................... 3-208
3.6.12.6.2.3. Unilateral and bilateral contact ....................................................................................... 3-210
3.6.12.6.2.4. Limited contact plane ...................................................................................................... 3-210
3.6.12.6.2.5. Locking contact ............................................................................................................... 3-212
3.6.12.6.3. Point-Curve contact ................................................................................................................ 3-213
3.6.12.6.4. Contact of circle with cylinder (curved axis) .......................................................................... 3-214
3.6.12.6.5. Sphere-Plane contact .............................................................................................................. 3-216
3.6.12.6.6. Circle-Plane contact................................................................................................................ 3-217
3.6.12.6.7. Sphere-Sphere contact ............................................................................................................ 3-217
3.6.12.6.8. Points | Sphere | Circle - Z surface contact ............................................................................. 3-219
3.6.12.7. T-forces .......................................................................................................................................... 3-221
3.6.12.7.1. Expression type of T-Force .................................................................................................... 3-221
3.6.12.7.2. File type of T-Force ................................................................................................................ 3-222
3.6.12.8. Special forces ................................................................................................................................. 3-223
3.6.12.8.1. Gearing ................................................................................................................................... 3-223
3.6.12.8.2. Chain gear ............................................................................................................................... 3-225
3.6.12.8.3. Cam ........................................................................................................................................ 3-227
3.6.12.8.4. Spring ..................................................................................................................................... 3-229
3.6.12.8.5. Rack and pinion ...................................................................................................................... 3-231
3.6.12.8.6. Bushing ................................................................................................................................... 3-233
3.6.12.8.6.1. Parameters of linear and pointwise bushings .................................................................. 3-233
3.6.12.8.6.2. Description of generalized bushing ................................................................................. 3-235
3.6.12.8.7. Combined friction ................................................................................................................... 3-237
3.6.12.8.7.1. Creation of element ......................................................................................................... 3-237
3.6.12.8.7.2. Choice of a pair of bodies and setting the attachment point ............................................ 3-238
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Chapter 3. Data input program
3.6.12.8.7.3. Specifying element axis .................................................................................................. 3-238
3.6.12.8.7.4. Assignment of image ....................................................................................................... 3-238
3.6.12.8.7.5. Setting axial force model................................................................................................. 3-239
3.6.12.8.7.6. Friction force parameters ................................................................................................ 3-240
3.6.12.8.7.7. Setting force element modes ........................................................................................... 3-240
3.7. UM COMPONENTS ............................................................................................................ 3-243
3.7.1. Basic notions ........................................................................................................................................... 3-243
3.7.2. List of components .................................................................................................................................. 3-245
3.7.3. Adding a component in visual mode ....................................................................................................... 3-245
3.7.4. Mode of adding elements with and without autopositioning .................................................................. 3-246
3.7.5. Standard library of visual components UMComponents ........................................................................ 3-246
3.7.5.1. List of standard components ............................................................................................................ 3-246
3.7.5.2. Visual adding generalized linear elastic or viscous-elastic forces ................................................... 3-247
3.7.5.2.1. Automatic positioning mode .................................................................................................... 3-248
3.7.5.2.2. The User's mode ....................................................................................................................... 3-249
3.7.6. Development of libraries of visual components ...................................................................................... 3-251
3.7.6.1. Wizard of components ..................................................................................................................... 3-251
3.7.6.2. Image of a component button .......................................................................................................... 3-252
3.8. SAVING OBJECT DATA ...................................................................................................... 3-253
3.9. GENERATION OF EQUATIONS OF MOTION........................................................................ 3-254
3.9.1. Numeric-iterative method ....................................................................................................................... 3-254
3.9.2. Symbolic method .................................................................................................................................... 3-255
3.9.3. Compilation of equations of motion ....................................................................................................... 3-256
3.10. IMPORT DATA FROM CAD PROGRAMS AND FORMATS .................................................. 3-257
3.10.1. UCF: UM CAD format ......................................................................................................................... 3-257
3.10.2. UMD format for models imported from CAD ...................................................................................... 3-257
3.10.3. Model processing after import from CAD ............................................................................................ 3-258
3.10.4. Reading 3ds files ................................................................................................................................... 3-258
3.11. IMPORT OF MSC.ADAMS MODELS .............................................................................. 3-260
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Chapter 3. Data input program
3. UM Input Program
3.1. What’s new in 7.0?
Here new UM elements and features, which are related to UM Input program, are listed.
1.
New function bodyinertia is added, which returns inertia parameters of bodies. The function
can be included in expression of any type, Sect. 3.5.2.4.4.
3.2. Data input program: general information
Program for development of models UM Input is intended for creation and correction of
multibody systems as well as for optional automatic generation and compilation of equations of
motion.
Basic elements of the program (UM Input) are the following (Figure 2.1):
 the main menu;
 the tool panel with buttons, which duplicate some most often used command of the main
menu;
 the tabs with standard and user defined components;
 the object constructor is the main tool for the model development.
The data input program is a multitasking tool, which allows opening several constructors
with description of different objects. An object, whose constructor is placed over all others, is the
active one.
Components
Constructor
of objects
Main menu
Buttons duplicating
main menu
Element
tree
Data inspector
List of identifiers
Figure 3.1. General view of UM Input program
Animation window
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Chapter 3. Data input program
To select an active object from the list of open models, the List of windows is used, Figure 3.2. The window is available by the Tools | List of windows menu command or by the
Alt+0 key.
Figure 3.2. List of windows as well as open objects
3.3. Options of Input program



To set or modify options of the Input program
run UM Input;
call the option window with the Tools | Options main menu command;
use the OK button of the window to store changes in the computer registry.
3.3.1. General options of the Input program
Figure 3.3. General options
Use the General tab (Figure 3.3) to specify the following parameters.
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Chapter 3. Data input program

Error when zero mass of a body
If the key is checked, zero mass is considered as an input error, else as a warning,
Sect. 3.6.9.2.
 Error when zero moment of inertia of a body
If the key is checked, zero inertia moment is considered as an input error, else as a warning;
 The default equation language
The option is taken into account if symbolic generation of equations is assigned to the object,
Sect. 3.9.2. Here the language for automatically generated equations of motion and programming
in the UM environment is selected. The choice depends on the presented compiler (Sect. 3.3.2);
 Default type of equation derivations:
o Symbolic – the equations are generated either in Pascal or C files and should be compiled as a DLL with an external compiler; programming in the Control file is available;
o Numeric-iterative – the equations of motion are generated during the simulation in
the numeric form; no external compiler is required; programming in the Control file
is not available;
 Undo after save – if not checked, the undo of old operations are not available after saving
the model;
 Open the last object – if checked, the latest active object will be opened automatically
when the Input program starts;
 Create body ‘Ground’ automatically
If checked, the fictitious ‘ground’ body is created automatically; this body is rigidly connected to the SC0; the ground body is used for visual coupling of model bodies to the SC0 by joints
or force elements with the help of connection points preliminary assigned to the ground.
 Save input.dat history – creates a copies of the model description file input.dat in the object directory after each saving the modified model;
 Open Pascal source files in – allows selecting an editor for programming on Pascal language.
 Open C source files in – allows selecting an editor for programming on C language.
Remark.
Handling zero inertia parameters as an error is recommended for beginners to
avoid the degeneration of the mass matrix at the simulation of objects. Besides,
the option is useful if the models simulation is done with the parallel solver on
multi-core processors, which requires all mass and moment of inertia to be nonzero.
3.3.2. Setup of symbolic generation of equations of motion
UM optionally generates equations of motion of objects with the help of a built-in specialized computer algebra system. To simulate the object dynamics, the equations should be compiled with the help of an external compiler (Delphi 4.0-7.0, Visual C++ 5.0-6.0, Borland C++
Builder 4.0-7.0, BDS 2005-2006), which is not delivered with UM. First of all, make sure that a
proper compiler is installed on your computer or on a server. Then use the General tab to set the
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Chapter 3. Data input program
default external compiler. In fact, UM can use numeric-iterative method of the generation of
equations of motion without an external compiler, Sect. 3.9.
3.3.2.1. Delphi
Use the Paths | Delphi tab (Figure 3.4) to specify paths to a Delphi compiler and the Delphi
VCL files. If the current computer has Delphi 4.0-7.0 (or higher) installed, it is enough to click
the Search Delphi button to set the paths. If Delphi can be found in the local net try to find it
automatically using the same button and the option Net turned on. In this case the paths will be
found if the registry of the corresponding net computer is available for reading. If reading the
registry is not allowed, the paths should be set manually. To do this, use the
buttons in the
right hand side of two boxes and find
 Delphi compiler dcc32.exe (usually [path to Delphi]\bin),
 Directory containing Delphi VCL *.dcu files (usually [path to Delphi]\lib).
Example:
 D:\Delphi7\bin\dcc32.exe,
 D:\Delphi7\lib.
Figure 3.4. Paths to Delphi
3.3.2.2. C++
Use the Paths | C++ tab (Figure 3.5) to specify paths to a C++ compiler. If the current computer has Visual C++ 5.0-8.0 or Borland C++ Builder 3.0-6.0, installed, it is enough to click the
corresponding button to set the paths. If C++ can be found in the local net, try to find it automatically using the same button and the option Net turned on. In this case the paths will be found if
the registry of the corresponding net computer is available for reading. If reading the registry is
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not allowed, the paths should be set manually. To do this, use the
side of two boxes and find
 C compiler cl.exe/bcc32.exe;
 Paths to C libraries (lib-files);
 Paths to the standard *.h files.
buttons in the right hand
Figure 3.5. Paths to C++



Example for Visual C++ installed on computer Suvorov:
\\SUVOROV\Program Files\Microsoft Visual Studio\VC98\bin\cl.exe
\\SUVOROV\Program Files\Microsoft Visual Studio\VC98\lib
\\SUVOROV\Program Files\Microsoft Visual Studio\VC98\Include
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3.3.3. Paths to external subsystems
Figure 3.6. Paths to external subsystem
Use the Paths | Subsystems tab (Figure 3.6) to add/delete paths to directories with external
subsystems. UM uses these paths to search external subsystems added to the current UM model.
Remark 1.
Remark 2.
The option is important if the Subsystems module is included in UM configuration, figure 3.7.
The path must leads to a directory, which contain UM models, and not directly to
an external subsystem.
Figure 3.7. UM configuration in the About window
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3.3.4. Paths to user’s files
Use the Paths | Search paths (Figure 3.8) tab to add/delete paths to directories with files,
which are used as parts of user’s code (programming in UM environment). The paths are used by
the external compiler if equations are generated in symbolic form, Sect. 3.9.
Figure 3.8. Paths to user’s units and files
3.3.5. Path to CADlook program
Use the Paths | CADlook (Figure 3.9) tab to add/delete path to commercial viewer of CAD
files CADLook for conversion of data from STEP (both AP203 and AP214), IGES, X_T (Parasolid), SAT formats, see Chapter 9 of the user’s manual.
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Figure 3.9. Paths to CADlook.exe
3.3.6. Component libraries
Use the Libraries tab to add or remove component library files, Sect. 3.7. To add a new
component library, click the
button and select the necessary file using the standard dialog
window Open. To remove a selected library, use the
button.
Figure 3.10. Component libraries
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3.4. Main menu commands and tool panel
3.4.1. File


New object (Ctrl+N) – creates a new model with the default name UmObj[Index] and
opens constructor.
Open object (Ctrl+O) – calls a special dialog box for choice of an existing object
(Figure 3.11). The dialog box contains a tree of objects found in the root directory. To set
the default path to the root directory use the
button in the top edit box to select a directory and the Accept as default button right after that.
Figure 3.11. Open object dialog box
Use the F5 button or the pop-up menu to refresh the tree of objects in the Open object dialog
box. Use the upper edit box for changing the current directory.
 Open *.umd – open file of object imported from CAD and save in the intermediate format
umd, Sect. 3.10.2.
 Import MSC.ADAMS – reading ADAMS files *.cmd, *.adm and conversion the model in
UM format, Sect. 3.11.
 Reopen – allows the user to open recently used objects.
 Save (Ctrl+S) – saves the active object in the object directory. The command is executed if
the active object has been modified and the object directory has already been created. If the
directory does not exist, the Save as… command is executed.
 Save as… – saves the active object in a directory pointed out by the user. Use the Save as...
dialog box to select or enter a path to the object including its name, Figure 3.12. If necessary, new directories are created. The object takes the last directory in the path as its own
name.
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Figure 3.12. Window contains path for save the model
Remark. Since UM 6.0 the object name (i.e. the last directory in the path) can include any
characters.
 Save as component – saving the model in a file with any name and extension to include the
model in the list of components, Sect. 3.7.1, or to merge the model with another one by the
Edit | Read from file menu command, Sect. 3.6.2.7.
 Exit (Alt+X) – close the program.
3.4.2. Edit







Copy to clipboard – copy parameters of selected elements to clipboard.
To clipboard as component – write parameters of the selected element and the assigned
graphic object to clipboard. If the element has no graphical object the option is disabled.
Copy into file… – write parameters of the selected element into file.
Save as component… – save parameters of the selected element and the assigned graphic
object in a file.
Insert – insert element/component from clipboard.
Read from file… – add all elements from file to the object.
UnDo, ReDo – commands of UNDO system.
3.4.3. Object


Verify data (F7) – verifies correctness of the object description.
Generate equations… (F8) – saves modified active objects, deletes old UMTask.dll file of
equations, and verifies the object description. If no errors are found, the window for generating and compiling equations starts. The tool is used if generation of equations in symbolic
form is assigned to the active object, Sect. 3.5.2.1/
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Figure 3.13. Window for generation of equations in symbolic form


Compile equations (Ctrl+F9) – compiling equations if they are generated in symbolic
form.
Simulation… (F9) – verifies whether the model is ready for simulation and runs the UM
Simulation program.
3.4.4. Add
The tree of menu command allows adding a new element with simultaneous assignment of its
type, Figure 3.14. Analogous commands are available in the tree of elements, Sect. 0.
Figure 3.14. Example: adding a graphic element “Cone”
3.4.5. Tools

Editor… – runs the built-in text editor.
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
Calculator of expressions… – runs the calculator of chains of symbolic expressions
(Sect. 3.5.2.4.2).
 Inspector (F12) – brings to front the Data Inspector for the active object if it is located on a
separate window (Sect. 3.5.2).
 List of elements (F11) – brings to front the Tree of elements for the active object if it is located on a separate window (Sect. 3.5.1.1).
 Identifiers (Alt+I) brings to front the List of Identifiers of the active object if it is located on
a separate window.
 List of windows (Alt+0) – calls the window containing the list of open windows.
 Control File… (Alt+C) – opens the Control file for the active object in the text editor.
 File of elements… – creates a file n[NameOfObject].txt in the object directory and opens it
in the text editor. The file contains lists of all the object elements (bodies, joints, identifiers,
force elements etc.) and their names.
 Import form CAD… – conversion CAD assemblies to UM format or reading files in ucf,,
3ds and stl formats. Sect. 3.10.
 Transformation of coordinates… (Alt+T) – opens the forms for transformation of coordinates of points into different system of coordinates (Sect. 3.6.10.5).
 Wizard of components… – tool for edition of component libraries.
 List of components… – open window with the list of loaded components.
 Button GO – a tool for creation of a small bmp file based on an animation window; can be
applied by adding a component to the list, Sect. 3.7.
 Options – opens a dialog box with UM options: paths to external compiler, standard and
user’s libraries etc. (Sect. 3.3).
Special tools (available if the corresponding UM module is included in the current configuration).
 Import wheel profile from CAD – tool for conversion in UM format of a railway wheel
profile created in a CAD program; requires UM Loco; see file 08_UM_LOCO.pdf,
Sect. Import wheel profile from CAD for more details.
 Train wizard – automatic generator of a train model with simplified one-dimensional vehicles; UM Train module is required; see file 15_UM_Train.pdf, Sect. Development of train
model for more details.
 Wizard of flexible subsystems – a tool for preparing data of flexible subsystems; UM FEM
module is required; see file 11_UM_FEM.pdf, Sect. Wizard of flexible subsystems.
3.4.6. Help




About UM context Help… the command opens the file with implementation of the context
UM help, file {UM Data}\MANUAL\UM_Context_Help.pdf.
Getting started – list of help files with examples of starting UM modules: UM Base, UM
Loco, UM Experiments, UM Automotive.
User’s manual – list of command to call of the manual pdf files.
About… – short information about UM version and the list of developers.
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3.4.7. Tool panel
Buttons located on the tool panel have the following functions:
creates a new object;
opens an existing object;
saves the active object;
saves the active object with a new name;
opens the text editor;
opens symbolic calculator;
verifies correctness of the active object description;
generates and compile equations for the active object;
compiles equations for the active object;
runs simulation of the active object.
import data from CAD;
wizard of components, Sect. 3.7;
list of components, Sect. 3.7.2;
buttons and menu of UNDO and REDO operations.
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3.5. Object constructor
3.5.1. Basic elements of constructor
Tabs with
components
Main
menu
Constructor
of objects
Buttons duplicating
main menu
Tree of
elements
Object
inspector
List of
identifiers
Animation
window
Figure 3.15. Object constructor
The object constructor allows describing an object or a multibody system as a set of standard
elements: bodies, joints, force elements. Basic parts of the constructor are the following.
 Object inspector is used for input and modification of object elements as well as some other information about the object.
 Animation window displays the object or its part according to the active elements presented in the inspector. It can be also used for visual construction of models.
 Tree of elements presents the lists of all object’s elements and organizes access to parameters of elements
 List of identifiers is used for modification of identifiers of the model. The list is the base of
the full parameterization of UM models (Sect.3.5.2.4.2).
 Tabs with components can be also considered as a useful tool of the constructor. This tool
allows adding to the model some simple standard elements.
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The drag-and-dock technology is used for the element tree, list of identifiers and the inspector. They can be removed from the constructor window and placed on a separate window with
the help of the mouse. If these tools are located in separate windows, the hot keys F11, F12,
Alt+I are used to bring them in front, Sect. 3.4.5.
3.5.1.1. Tree of elements
An object is a multibody system, which consists of separate typical elements. Access to the
elements is realized by means of the list of elements (Figure 3.15), visually (3.5.1.2) or with the
help of hot keys (3.5.3).
Figure 3.16. List of object elements
Click on a list item (figure 3.16) calls the corresponding information in the object inspector
(3.5.2). The tree contains the following items:
 Object – general object options, gravity, background color, lists of variables, curves, sensors etc. (3.5.2.1).
 Subsystems – list of subsystems. For UM version with subsystem technique only,
Sect. 3.6.3.
 Images – list of images, which are used for visualization of the scene, bodies and force elements (0).
 Bodies – list of bodies and their parameters (mass, moments on inertia, coordinates of centers of mass etc., Sect.3.6.9).
 Joints – input of joints (rotational, translational etc.) as well as coordinates of bodies
(Sect.3.6.11).
 Bipolar forces – list of bipolar forces, i.e. forces acting along the axis of element, which
connects two points of bodies (Sect.3.6.12.1). The force element is used for modeling
dampers, leads etc.
 Scalar torques – a list of torques, acting by rotation of body relative to some axis,
Sect. 3.6.12.3.
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Linear forces – list of generalized linear force elements described by 6  6 stiffness and
damping matrices (Sect.3.6.12.3). The element is used for modeling springs, linear bushings
etc.
Contact forces – list of force elements, which models contact interaction between bodies
(Sect.3.6.12.6).
T - forces – list of forces and torques which components can be functions of time or kinematic functions, Sect. 3.6.12.7.
Special forces – models of special force interactions (gearing, cams, combined friction,
bushings etc. Sect. 3.6.12.8).
3D Contact – setting for 3D contact model. Reserved for future use. For more detailed description of using 3D Contact see Sect. 3.6.9.7.
Connections – a tool for assignment of attachment points for external force elements. For
UM version with subsystem technique only, Sect. 3.5.2.3.1, 3.6.3.3.1.
Indices – internal UM indices of object elements and coordinates, Sect. 3.5.2.3.2.
Summary – contains information about correctness of the object description as well as lists
of errors and warnings, Sect. 3.5.2.3.3.
Coordinates – a list of current values of model coordinates; the tool is used for change of
the coordinates, Sect. 3.5.2.3.4.
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3.5.1.2. Animation window
3.5.1.2.1. Visualization of object elements
The whole object or active elements are visualized in the animation window depending on
the window mode (Sect.3.5.1.2.2). The following types of visual elements are used for visualization of different elements:
 Graphic objects (GO) created by the user – for bodies, bipolar and generalized linear force
elements, special force elements spring, rod constraint images (Sect. 3.6.8);
Figure 3.17. Visualization commands
Figure 3.18. Icons for joints:

Icons – for joints, T-force, linear and special force elements, bushings, external elements etc
(Figure 3.17);
 Points.
Every type of listed visual elements has active regions, which are used for visual selection of
the corresponding object elements by the mouse.
 GO – the active region is the whole image;
 Icon – the active region is a small neighborhood of the left bottom part pointed out by the
arrow, e.g. for the joint icon:

Point – active region is a small neighborhood of the point.
3.5.1.2.2. Modes of animation window
Animation window has two modes of visualization of an object. The button
Mode | Object/Element command of a pop-up menu are used to switch them.
 Whole object mode
or the
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The whole object is visualized. In this mode, a mouse click on the active region of an image
makes the corresponding element active (body, joint and force element, Sect. 3.5.1.2.1.
 Single element mode
A separate element is visible in this mode: GO, body, joint or force element (together with
connected bodies).
Graphic modes
a)
b)
c)
d)
Figure 3.19. Different modes of visualization
- wired graphics, Figure 3.19a
- wired, invisible edges are hidden, Figure 3.19b
- surfaces with edges, Figure 3.19c
- surfaces without edges, Figure 3.19d
Perspective type is switched by the Perspective command of the popup menu or by the
button on the tool panel.
Parameters of the perspective are changed in the window available by the Window parameters command of the popup menu.
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3.5.1.2.3. Basic system of coordinates, pop-up menu
The basic system of coordinates (SC0) is optionally presented in the animation window. Use
the Coordinate system command of the pop-up menu to visualize of hide the axes. Coordinates
of all elements attached the base must be given in this SC. A color principle is used to identify
the SC0 axes (RGB):
 axis X is red;
 axis Y is green;
 axis Z is blue.
A coordinate grid coincides with one of the coordinate planes. Use the Window parameters
command of the pop-up menu to change the grid size and step.
Use the right mouse button to call a pop-up menu (Figure 3.20).
Figure 3.20. Popup menu of animation window





Menu commands:
Orientation – choice of one of the standard object orientations.
Grid – choice of one of the standard grid locations.
Click an image of the SC0 axis to set the grid perpendicular to the corresponding axis
Rotational style – choice the style of rotation for objects in the animation window: Z-style
is used by default (from UM 3.0), On sphere – the style usually used in CAD systems.
Selection style – the style of graphical visualization of an active element of the object (image contours or box rounding the element image).
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Coordinate system – turn on/off visualization of SC0.
Smoothing – turn on/off of smoothing mode.
Perspective – turn on/off of orthogonal projection.
Contour graphic mode – is used to obtain contrast black-and-white image which is suitable
for printing.
Show icons – is used for visualization of icons for joints, force element of general type,
generalized linear force element etc. (for the whole object mode in the animation window
only, Sect.3.5.1.2.2).
Mode – switching the animation window modes (whole object / active element,
Sect.3.5.1.2.2).
Window parameters – call of a window with perspective and grid parameters.
Background color – setting the background color of the animation window.
Visible side of ASC – mode of drawing the ASC surfaced imported from CAD. One side
drawing is faster.
3.5.1.2.4. Tool bar
– Copy the window to clipboard or to a file (bmp).
– Zoom in the selected area of animation window.
– Show all (F9).
– Zoom in/out of a selected point on the object: click the button and immediately click
the left/right mouse button on an image point to zoom in/out the object and to shift the point in
the window center. Use also Alt+Shift + mouse click on an object point.
– Shift mode (Ctrl + left mouse button).
– Zoom mode (Shift + left mouse button).
– Rotation mode (left mouse button).
- Mode of simplified drawing by mouse operation in animation window (rotation, shift).
A parameter of the simplification is set on the Object | Options | Animation tab of inspector,
the parameter Bound of visibility by simplified drawing, Sect. 3.5.2.1.2.
- switch on/off visual operations with mouse in animation window; the mode must be off
is the visual adapter is too slow for such mouse operations.
– graphic mode in animation window, Sect. 3.5.1.2.2.
– Turn on/off perspective.
– Choice of one of standard views.
– Switch full object / single element mode (Sect.3.5.1.2.2).
– Show element icons in the full object mode.
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- The buttons call the procedure for computations of constraint equations it the model
has closed kinematic loops and cut joints, See Charter 2, Sect. System graph. Closed kinematical
loops; Theoretical foundations for solving constraint equations.
See also Sect.3.5.5.3 for a list of hot keys.
3.5.1.2.5. Additional possibilities for object translation/rotation by mouse
Modes for shift, rotation of objects, zoom and so on can be activated by the mouse using buttons on the tool panel of animation window, Sect. 3.5.1.2.4. Here we consider some additional
possibilities, in particular using keyboard keys.
Rotations:


if the mouse cursor is
, press the left mouse button, keep it and move the cursor on the
windows;
if the mouse cursor points a definite element of the object like a body, press the mouse
wheel and keeping it shift the mouse cursor.
Shifts: press the Ctrl and keep it. If the mouse cursor is , press the left mouse button, keep
it and move the cursor on the windows; if the mouse cursor points a definite element of the object like a body, press the mouse wheel and keeping it shift the mouse cursor.



Zoom:
rotate the mouse wheel forward/backward;
press the Shift key and keep it; If the mouse cursor is
, press the left mouse button, keep
it and move the cursor on the windows up and down;
press the Shift+Alt key and keep it. Move a bit the cursor until it looks like ; point the
cursor on the point for zoom and click the left (zoom in) or right (zoon out) mouse button.
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3.5.2. Data inspector and some features of object element description
3.5.2.1. Object parameters and options
Use the Object tab of the inspector to set some parameters and options for the current model
as well as to define lists of variables, sensors, curves etc.
3.5.2.1.1. “General” tab
Figure 3.21. Object general parameters and options
The following parameters are set in the Object | General tab of the inspector, Figure 3.21.




The Transform into subsystem button transforms all elements of the object into an included subsystem of the object. This tool is used by development of an object as a tree of subsystems as well as for creating components in particular suspensions in the module UM
Tracked Vehicle. After running the operation, the active object includes one subsystem,
which is equivalent to the object before making the operation.
The Path label contains the path to the current model.
Object identifier is used only if equations are generated in symbolic form. The identifier is
included in the names of files with equations as well as in names of some standard structures within these files. In earlier version of um before UM6.0, the name of the object was
used as the identifier, which imposed restrictions of the object name. Now the restrictions
on the object name are removed.
Generation of equation group allows the user to set either symbolic or numeric-iterative
methods for generation of equations of motion, Sect. 3.9.
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Direction of gravity is set by a vector, which specifies the direction of gravity force relative
to SC0. Vector components can be set as constant expressions or identifiers. To turn off the
gravity, set zero value for the vector components. If the length of the vector is not equal to
unity, the gravity acceleration decreases or increases proportionally. The direction of gravity
for all subsystems of the objects is imposed by the main object. This means that the directions specified in the subsystems (both included and external) are ignored.
Characteristic size allows decreasing/increasing the default size of images in the animation
window. In particular, this parameter is used for obtaining proper vector sizes for small or
large objects.
Scene image drop-down menu is the assignment of a graphic object, which corresponds to
fixed elements of the object as well as to environment. Press the Delete key to cancel the assignment of the scene image.
Compute edges for ASC is visible if the model includes graphic elements of the ASC type
imported from CAD programs without conversion of edges. The key can be used for automatic computation of edges and improving the images, see Sect. 0.
3.5.2.1.2. “Option” tab
Figure 3.22. Tabs of the inspector and animation window options
The Object | Options tab contains values of stepwise changing angular and linear variables
when special buttons in edit boxes are used
Angular variables are measured in degrees within the Input program and in radians in the
simulation program.




Use the Object | Animation window tab to set
the selection style either by bounds or edges, Figure 3.23;
mouse rotational style;
the background and grid colors; click the color box by the mouse to choose the color;
bound of visibility in percents by simplified drawing during rotations and shifts of object by
the mouse.
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Figure 3.23. Selection by edges (left) and bounds (right)
3.5.2.1.3. “Sensors/LSC” tab
Figure 3.24. List of sensors
A list of sensors is created on the Object | Sensors/LSC | Sensors tab, Figure 3.24. The Object | Sensors/LSC | Local SC tab is reserved for the future applications and is not used in
UM7.0.
A sensor is a point with parameterized coordinates relative to some of the bodies. During the
simulation, the user can get plots of kinematic characteristics of the body related to the sensor:
coordinates, velocity, acceleration of the sensor point.
The advantage of using the sensors in comparison with usual kinematic variables created
with the Wizard of variables consists in the possible parameterization of point coordinates, see
Chapter 4, Sect. Wizard of variables | Sensors.
Steps by creation of a sensor:
 create necessary connection points for a body, Sect. 3.6.9.6;

click on the button
ure 3.25;
in inspector; connection points appear in animation window, Fig-
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Connection point
Figure 3.25. Connection point in animation window


select a point by the mouse to add it to the list as a sensor;
rename the sensor if necessary.
Remark.
Creating the parameterized kinematic variables is possible with the elements of
the list of variables, Sect. 3.5.2.1.4.
Model: {UM Data}\SAMPLES\LIBRARY\Pendulum.
3.5.2.1.4. “Variables” tab
Figure 3.26. Example of list of variables
The Object | Variables tab, Figure 3.26, is used for development of a list of variable functions, which extend considerably description of non-standard force interactions, surfaces and
kinematic variables, Sect. 3.5.2.4.8.
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3.5.2.1.5. “Curves” tab
Figure 3.27. Example of a curve
With the Object | Curves tab, Figure 3.27, the user develops a set of 3D curves, which are
used in the Point-Curve contact force element, Sect. 3.6.12.6.3. Detailed information about creating a curve can be found in Sect. 3.6.7.
3.5.2.1.6. “Attributes” tab
Figure 3.28. Example of use of attributes in the model of a tracked vehicle
The Object | Attributes tab, Figure 3.28, is used for internal identification of some elements
of models of tracked vehicle, Chapter 18.
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3.5.2.2. Lists of elements of a definite type
Each object (multibody system) consists of sets of elements, most of which are grouped as
lists. Every list contains elements of a single type, e.g., lists of bodies, joints, bipolar force elements and so on. Each element of a list has a name, which is an arbitrary set of symbols. The
name of element is the base of its identification, and the name must be unique within the corresponding list, that is, it is not allowed setting one name for two elements of the same type (e.g.,
for two bodies). Elements of different lists as well as elements, which belong to different subsystems, may have the same names. So, the body and its image (or a joint) can have equal names.
The tree of elements of the model is used for access to parameters of an element of a list,
Sect. 3.5.1.1.
Standard interfaces are used to manage the lists within the data inspector.
a
b
Figure 3.29. Lists
Figure 3.29a shows an empty list in the inspector, Figure 3.29b shows an element of the list
of bodies.
Edit box for the name and three buttons are located in the top of the tab:
adds a new element to the list;
creates an exact copy of the current element and adds it to the list;
deletes the current element.
See also Sect. 3.5.5.4.
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Chapter 3. Data input program
Press the Enter key after modification of the name else the changes can be lost.
3.5.2.3. Auxiliary tabs in inspector
3.5.2.3.1. External connections
Figure 3.30. Example of the list of external connections
The tab contains a list of external elements of the object, which are included in subsystems,
Figure 3.30. The list is used for assignment of the second bodies as well as connection points to
external force elements, Sect. 3.6.3.3.
3.5.2.3.2. Indices
Figure 3.31. Example of the list of element indices
The tab contains a list of object elements including all elements of subsystems. Indices of elements are used by programming in UM environment (obsolete), see Chapter 5.
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Chapter 3. Data input program
3.5.2.3.3. Summary
The summary tab contains information about correctness of description of the object.
Figure 3.32. Description of the object does not contain errors
The model is ready for simulation if no errors found, Figure 3.32. Warnings do not affect the
status of ready object but can lead to simulation errors.
Figure 3.33. Model contains errors and warnings
When errors found, Figure 3.33, the simulation is not allowed for the object. Click on the error of warning line opens the corresponding element in the inspector.
3.5.2.3.4. Coordinates
Figure 3.34. Example of the list of coordinates
The Coordinates tab is used for changing values for joint coordinates and body positions,
Figure 3.34. The list contains all coordinates of the model including coordinates in subsystems.
See Chapter 4, Sect. Choice and automatic calculation of the initial conditions for more details.
If the coordinate tab is active, the user can change positions of bodies by the mouse in the animation window, Figure 3.35:

move the mouse cursor to the desired body until it changes to
;
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Chapter 3. Data input program
press the left mouse button and drag the body.
Remark.
Shift of bodies by the mouse is usually applied in the case of simple models with
small number of bodies. The operation is not recommended for models of rail vehicles, cars, and tracked vehicles.
Figure 3.35. Example of shift of bodies by mouse
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Chapter 3. Data input program
3.5.2.4. Data types
Information for each element of an object (element parameters) is entered in boxes in the object inspector. UM uses several standard data types. The user must know features of each data
type to work with UM correctly.
A very important feature of object description using UM is the data parameterization. This
means that many element parameters could be set not only by its numeric values but by expressions including numbers, identifiers, operations and functions. Consider the basic types of data
presented in UM.
3.5.2.4.1. Numeric constants
UM uses standard syntax for numbers.
Examples: 1.23, 0.256e-3
3.5.2.4.2. Identifiers
Identifier is a set of symbols, which includes Latin letters, digits and character “_”.
The first symbol in the identifier cannot be a digit or character “_”.
Identifiers with the character “_” as the first symbol are reserved for internal presentation of
identifiers in equations of motion generated by the program.
Reserved words of Pascal and C languages cannot be used as identifiers.
The program verifies syntax of entered expressions. If a new identifier is found, it is added to
the list of identifiers of the object (Sect. 3.5.3).
Example of correct identifiers:
mass_1 length_of_rod cdiss cstiff
Examples of wrong identifiers:
2mass – the first symbol is the digit 2;
_length – the first symbol is the character “_”;
mass% - prohibited character “%”;
do, as, while – reserved words of the Pascal language.


There exist two types of identifiers:
Identifier – number;
Identifier – expression.
Values of identifiers of the first type can be changed both in the Input and in the Simulation
programs. Identifiers of the second type are presented by arbitrary expressions, which include
 numbers;
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
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Chapter 3. Data input program
identifiers of the first and the second types;
standard functions (Sect. 3.5.2.4.3).
Chains of calculations may be programmed with the help of identifiers of the second type.
An example of a chain including identifiers of the both types is shown below.
Name
Expression
Mass
1.12
Mass of rod
length
0.55
Length of rod
ix
mass*length^2/12
0.0282333333
Moment of inertia of the rod relative to X axis
iy
ix
0.0282333333
Moment of inertia of the rod relative to Y axis
Remark.
Value
Comments
An expression can only include identifiers located above the current identifier.
The same principle is used in the built-in calculator (the menu Tools | Symbolic calculator
command).
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Chapter 3. Data input program
3.5.2.4.3. Standard functions and constants
The following standard functions can be used for description of data of several types (explicit function, identifiers-expressions):
 sin, cos – trigonometric functions, arguments are set in radians;
 arcsin, arccos, arctan – inverse trigonometric functions (rad);
 arctan2(x, y) computes an angle , tan   x / y in radians in the interval from - to ;



quadrant for the angle is defined by signs of arguments x,y as if x  sin , y  cos  ;
exp – natural exponent;
ln – natural logarithm;
abs – absolute value;
 1, x  0

sign x    0, x  0
 1, x  0


sign –



b
^ – power function, the expression a^b corresponds to a , the exponent must be an integer
if the base is negative;
sqr – square;
sqrt – root square;

1, x  0

0, x  0
Heavi – Heavi(x) = 

 v1, c  0

if( c , v1 , v2 , v3) = v 2, c  0
 v3, c  0

x1
h1
x0
x
h0
Figure 3.36. Step function
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Chapter 3. Data input program

h0 , x  x0

x  x0
2
h0  ( h1  h0 )d (3  2d ), d 
x1  x0


h1, x  x1
step( x , x0 , h0 , x1 , h1 )=
As a rule, the Step function is used for a smooth but fast transition of expression from one
value to another. Example of the function step( t , 0.1 , -0.2 , 0.15 , 0.3 ) is shown in Figure 3.36.

The ‘bodyinertia’ function is considered as a standard function as well, and can be included
in expression of any type, see Sect. 3.5.2.4.4.
Standard constants
pi : number   3.1415926536...
e : number e=2.7182818285
rtod: factor converting radians to degrees, e.g. arctan(1)*rtod=45;
dtor: factor converting degrees to radians, e.g. 90*dtor=pi/2;
itom = 0.0254: factor converting Inch TO Meter;
mtoi = 1/itom: factor converting Meter TO Inch;
pton = 453.6/1000*9.81: factor converting Pound-force TO N;
ntop = 1/pton: factor converting inch to meter N TO Pound-force.
3.5.2.4.4. Function bodyinertia – inertia parameters
‘Bodyinertia’ is a standard function, which allows the user to get inertia parameters of bodies
and include them in expression of any types: identifiers (Sect. 3.5.3), force element parameters,
variables (Sect. 3.5.2.4.8). Function syntax:
bodyinertia( _inertia_name , _body_name )
Here
_inertia_name is a standard designation of inertia parameter from the following list (please
do not mix up with identifiers from the identifier list!):
m – mass
ix – moment of inertia relative to the X axis;
iy – moment of inertia relative to the Y axis;
iz – moment of inertia relative to the Z axis;
ixy, ixz, iyz – centrifugal moments of inertia;
cx, cy, cz – coordinates of center of mass relative to the body-fixed SC.
The function returns numerical values, which exactly correspond to the inertia parameters
specified by the user for the corresponding body, Sect. 3.6.9.2.
_body_name – name of body.
The function is recommended to be used when inertia parameters are computed by the body
image.
Function writing can be effectively done with the help of the expression editor, Sect. 0.
Example:
sqr(2*pi*f)*bodyinertia(m , "bogie1.body1" )
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Chapter 3. Data input program
The mass of body ‘bogie1.body1’ is included in this expression.
bodyinertia(ix , "body" )
This function returns the moment of inertia of the body ‘bogie1.body1’.
Example of a model:
{Path to UM data}\Samples\Library\BodyInertia_test
In this model, the function ‘bodyinertia’ is used in the identifier list, in expression for bipolar
force, and in the list of variables.
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Chapter 3. Data input program
3.5.2.4.5. Constant symbolic expressions




A constant symbolic expression is an expression, which contains
identifiers;
numbers;
additions, subtractions, divisions and multiplication;
standard functions (Sect. 3.5.2.4.3, 3.5.2.4.4).
It is not allowed the use of identifier t (time).
Example of correct constant symbolic expressions:
sqrt(2)*b1+sqrt(a1+a2)/2
The constant symbolic expressions can be used for the most of the element parameters (inertia and geometric parameters, coordinates of attachment points of force elements, sizes of graphic elements, coefficients of stiffness and damping and so on). The corresponding edit boxes in
the data inspector have the standard interface
Figure 3.37. Exit box for constant expressions
The letter ‘c’ in the right top part of the box points out that the parameter can be a constant
expression. Double click on the box or click on the ‘c’ letter calls a tool for visual construction of
the expressions, Sect. 0.
3.5.2.4.6. Expression – explicit function
The expression of this type includes
 numbers;
 identifiers;
 standard functions;
 standard variables (t, x, v, p1, p2, p – depending on type of function).
Double click the edit box to call a tool for writing the expressions, Sect. 0. The corresponding window contains the lists of identifiers and allowed variables as well as buttons with standard functions.
Consider types of explicit functions
3.5.2.4.6.1. Function of time - t


The standard variable is t – time. The function is used for description of joints
joint of generalized type, elementary transformation of types tt, rt (Sect. 3.6.11.7.4);
rotational and translational joints in the cases when the joint coordinate is an explicit function of time (Sect. 3.6.11.4);
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Chapter 3. Data input program
components of a T-force, Sect. 3.6.12.7.
The corresponding edit boxes in the data inspector have the following standard interface:
The letter ‘t’ in the right top part of the box points out that the expression is a time function.
3.5.2.4.6.2. Scalar force and torques of the Expression type: x, v, t





See Sect. 3.6.12.2.8. Standard variables are t (time) as well as two additional variables x, v.
The function is used for description of mathematical models of forces in the following cases:
Bipolar force element; x is the length of the element; v is the time derivative of the length,
Sect. 3.6.12.3;
Scalar torque; x is the rotation angle; v is the time derivative of the angle, Sect. 3.6.12.4;
Joint forces in the case of joint of general type (elementary transformations rv, tv, type of
force is expression, Sect. 3.6.11.7.3, as well as for translational and rotational joints,
Sect. 3.6.11.4; x is the value of coordinate, v is its time derivative;
Description of an axle force in the case of a special force of the Combined friction type;
Components of bushing force elements of the generalized type, Sect. 3.6.12.8.6.2.
The corresponding edit boxes in the data inspector have the following standard interface
(Figure 3.38).
Figure 3.38. Exit box for Pascal/C expressions
The letter ‘p’ – Pascal – in the right top part of the box points out that the data is a function of
x, v, t.
3.5.2.4.6.3. Curves as expressions


The standard identifier p is used for parameterization of curves in the following cases:
2D profile or axis curves as expressions in the case of a profiled graphic element,
Sect. 3.6.8.2.8;
3D curves as expressions, Sect 3.6.7.2.
3.5.2.4.6.4. Functions of description of parametrical graphic elements
Standard variables are p1, p2 parameterize a surface or a curve, Sect. 3.6.8.2.7.
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Chapter 3. Data input program
3.5.2.4.6.5. Z –surfaces
Surfaces z  f x, y  in 3D space are used in description of Point -- Z –surface, Circle -- Z –
surface and Sphere - Z – surface contact force elements, Sect. 3.6.12.6.8.
Standard variables are p1, p2 parameterize a Z-surface. The corresponding edit boxes in the
data inspector have the standard interface shown in Figure 3.38.
3.5.2.4.7. Kinematic functions
Figure 3.39. Expression editor and list of kinematic functions
The user can use kinematic functions depending on relative positions and velocities of bodies
by description of some force elements.
The following force elements allow using the following kinematic functions:
 scalar force of the Expression type, Sect. 3.6.12.2.8 in description of force elements
o bipolar force, Sect. 3.6.12.1,
o joint forces, Sect. 3.6.11.7.3,
o scalar torque, Sect. 3.6.12.3,
o axial force in models of combined friction, Sect. 3.6.12.8.7.5;
o components of force and torque in case of bushing of generalized type,
Sect. 3.6.12.8.6.2;
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Chapter 3. Data input program
components of T-force in the case of the Expression type, Sect. 3.6.12.7.
Access to the kinematic functions is realized by the expression edit window, Figure 3.39,
Sect. 0. The function template is added to the expression after double click on the function name
in the list. The user should set real parameters of function in the template. Example of template:
vx( _to_point , [_from_point] , [_SC_component] , [_SC_deriv] ).
The following designations are used as template arguments:
_to_point is the first connection point;
_from_point is the second connection point;
_SC_component is the local system of coordinates (SC), in which vector components are
defined;
_SC_deriv is the local system of coordinates (SC), in which vector time derivative is evaluated;
_to_SC is the first local SC;
_from_SC is the first local SC.
All systems of coordinates are specified by the oriented connection points, Sect. 3.6.9.6.2.
Optional arguments are written in square brackets. To omit the optional argument, a white
space can be set. Example (the second argument is omitted):
dy(“Bogie.Frame.Point 2”, , “Body.Local SC”)
3.5.2.4.7.1. Function coordinate
The function returns a joint coordinate or first/second time derivative of the coordinate.
Template of the function:
coordinate( _joint , _index , _type )
Arguments:
_joint – name of joint;
_index –index of the coordinate starting with 1;
_type – type of output (0 - coordinate, 1 – first time derivative of the coordinate, 2 – second
time derivative of the coordinate).
Examples
coordinate( “jBody” , 4 , 0 )
The function returns a value of the fourth coordinate in joint jBody.
coordinate( “Bogie1.jFrame” , 2 , 1 )
The function returns the first derivative in time of the second coordinate in joint Bogie1.jFrame.
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Chapter 3. Data input program
3.5.2.4.7.2. Functions dm, dx, dy, dz
These functions determine the length (dm) or projections (dx, dy, dz) of a vector BA , which
connects two fixed points A, B of a pair of bodies, Figure 3.40. The projections are evaluated
relative to the SC C.
A
B
C
Figure 3.40. Vector connecting fixed points of two bodies
Mathematical model
The vector BA is computed according to the formula
BA  rA  rB ,
where rA , rB are radius vectors to points A, B with respect to SC0.
Function templates:
dm( _to_point , [_from_point] )
dx( _to_point , [_from_point] , [_SC_component] )
dy( _to_point , [_from_point] , [_SC_component] )
dz( _to_point , [_from_point] , [_SC_component] )
Arguments:
_to_point is name of connection point A;
_from_point is name of connection point B;
_SC_component is name of oriented connection point C.
Names of connection points include long names of bodies. As a rule, the name should be put
in quotes.
If point B is omitted, it is located in the origin of SC0.
If SC C is omitted, the projection is computed on axis of SC0.
Examples.
dx( "Car body.Center of mass")
The function returns the coordinate x of connection point “Center of mass” of body “Car
body” in SC0.
dm("Car body.Center of mass", “Bogie1.Frame.Point 2”)
The function returns the distance between two points.
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Chapter 3. Data input program
dy(“Bogie1.Frame.Point 2”, "Car body.Center of mass", “Car body.Local SC”)
The function returns the y projection of vector connecting points “Bogie1.Frame.Point 2”,
"Car body.Center of mass" on the SC specified by the oriented connection point “Car body.Local
SC”.
3.5.2.4.7.3. Functions vm, vx, vy, vz, vr
These functions determine the magnitude (vm), projections (vx, vy, vz) or the radial component (vr) of a difference of velocities of two points A, B v BA of a pair of bodies, Figure 3.40.
The projections are evaluated relative to the SC C. Velocities are computed relative to SC D (not
shown in the figure).
Mathematical model
Velocity v BA is evaluated according to the formula
v BA  v A  v B .
where v A , v B are the velocities of points A, B relative to SCD. The result depends on the
body, which the SCD belongs to, and does not depend on the position and orientation of SCD
relative to this body.
The bipolar or radial velocity is equal to the separation velocity between points A, B. It is
computed as
vBA, r  ( v A  v B )  e BA
,
where e BA is the unit vector from point B to point A. The result does not depend on SCD,
and velocities are computed relative to SC0.
Function templates
vm( _to_point , [_from_point], [_SC_deriv] )
vx( _to_point , [_from_point] , [_SC_component] , [_SC_deriv] )
vy( _to_point , [_from_point] , [_SC_component] , [_SC_deriv] )
vz( _to_point , [_from_point] , [_SC_component] , [_SC_deriv] )
vr( _to_point , [_from_point] )
Arguments:
_to_point: name of connection point A;
_from_point: name of connection point B;
_SC_component: name of oriented point C.
_SC_deriv: name of oriented connection point D, i.e. SC relative to which the time derivative
are computed.
Names of connection points include long names of bodies. As a rule, the name should be put
in quotes.
If point B is omitted, it is located in the origin of SC0.
If SC C is omitted, the projection is computed on axis of SC0.
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Chapter 3. Data input program
If SC D is omitted, velocities are calculated relative to SC0.
Examples.
vy(“Bogie1.Frame.Point 2” , “Car body.Local SC” , “Car body.Local SC”, “Car
body.Local SC”)
The function returns the y component of the velocity of point “Bogie1.Frame.Point 2” relative to SC “Car body.Local SC”.
vm( "Car body.Center of mass")
Magnitude of velocity of point "Car body.Center of mass" relative to SC0.
3.5.2.4.7.4. Functions ax, ay, az
These functions return angles of rotation of SCA about one of the axis of SCB, Figure 3.41.
The angle of rotation relative to a definite axis is calculated correctly, if rotations about two other
axes are small and do not exceed 10 degrees.
A
B
Figure 3.41. On definition of systems of coordinates
Mathematical model
Angles of rotation are calculated as
ax :   arctan2 ( k A  jB , k A  k B ),
ay :   arctan2 ( k A  i B , k A  k B ),
az :   arctan2 (i A  jB , i A  i B ),
where i, j, k are the unit vectors along the axes of SCA and SCB.
Function templates
ax( _to_SC , [_from_SC] )
ay(_to_SC , [_from_SC] )
az(_to_SC , [_from_SC] )
Arguments
_to_SC is name of oriented point A;
_from_SC is name of oriented point B.
Names of connection points include long names of bodies. As a rule, the name should be put
in quotes.
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Chapter 3. Data input program
If point B is omitted, rotation of SCA relative to SC0 is considered.
Example
az("Body.Local SC")
The function returns the angle of rotation of body Car body relative to the axis Z of SC0.
3.5.2.4.7.5. Function angle
b




O
a

O





N
L
Figure 3.42. Euler angles (left) Cardan angles (right)
The function returns one of three orientation angles of SCA relative to SCB, Figure 3.41.
Orientation angles as a sequence of three rotations are introduced in Chapter 2, Sect. Joint with
six degrees of freedom. Examples of orientation angles: Euler angles (, , ), sequence of rotations 3,1,3; Cardan angles (α,β,), sequence of rotations 1,2,3, Figure 3.42.
Table 1
Types of orientation angles
_angle_type
0
Sequence
(3,1,3)
1
2
3
4
5
6
7
8
9
(1,2,3)
(1,3,2)
(3,2,1)
(3,1,2)
(2,1,3)
(2,3,1)
(1,2,1)
(1,3,1)
(2,1,2)
Comments
Euler angles: precession, nutation, intrinsic
rotation
Cardan angles
Yaw, pitch, roll
Wheelset angles
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Chapter 3. Data input program
(2,3,2)
(3,2,3)
Function template
angle( _to_SC, _angle_type, _index, [_from_SC] )
Arguments
_to_SC: name of oriented point A;
_angle_type: type of orientation angles, Table 1;
_index: index of angle 1, 2 or 3;
_from_SC: name of oriented point B;
Names of connection points include long names of bodies. As a rule, the name should be put
in quotes.
If point B is omitted, orientation of SCA relative to SC0 is considered.
Example
angle( "Car body.Local SC", 3, 1)
angle( "Car body.Local SC", 3, 2)
angle( "Car body.Local SC", 3, 3)
The function returns yaw, pitch or roll angles of Car body relative to SC0.
Models:
{UM Data}\SAMPLES\LIBRARY\Variables_and_Kinematic_Functions\Yaw_Pitch_Roll;
{UM Data}\SAMPLES\LIBRARY\Variables_and_Kinematic_Functions\Euler_angles.
3.5.2.4.7.6. Functions yaw, pitch, roll
The functions return yaw, pitch or roll angle. Sequence of rotations: (3,2,1), Sect. 3.5.2.4.7.5.
Function templates
yaw( _to_SC, [_from_SC])
pitch( _to_SC, [_from_SC])
roll( _to_SC, [_from_SC])
Arguments
_to_SC is name of oriented point A;
_from_SC is name of oriented point B;
Names of connection points include long names of bodies. As a rule, the name should be put
in quotes.
If point B is omitted, orientation of SCA relative to SC0 is considered.
Correspondence to the angle function:
yaw( _to_SC, [_from_SC]) = angle( _to_SC, 3, 1, [_from_SC]);
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Chapter 3. Data input program
pitch( _to_SC, [_from_SC]) = angle( _to_SC, 3, 2, [_from_SC]);
roll( _to_SC, [_from_SC]) = angle( _to_SC, 3, 3, [_from_SC]);
Model:
{UM Data}\SAMPLES\LIBRARY\Variables_and_Kinematic_Functions\Yaw_Pitch_Roll.
3.5.2.4.7.7. Functions psi, theta, phi (Euler angles)
The functions return one of the Euler angles. Sequence of rotations: (3,1,3), Sect. 3.5.2.4.7.5.
Function templates
psi( _to_SC, [_from_SC])
theta( _to_SC, [_from_SC])
phi( _to_SC, [_from_SC])
Arguments
_to_SC is name of oriented point A;
_from_SC is name of oriented point B;
Names of connection points include long names of bodies. As a rule, the name should be put
in quotes.
If point B is omitted, orientation of SCA relative to SC0 is considered.
Correspondence to the angle function:
psi( _to_SC, [_from_SC]) = angle( _to_SC, 0, 1, [_from_SC]);
theta( _to_SC, [_from_SC]) = angle( _to_SC, 0, 2, [_from_SC]);
phi( _to_SC, [_from_SC]) = angle( _to_SC, 0, 3, [_from_SC]);
Model:
{UM Data}\SAMPLES\LIBRARY\Variables_and_Kinematic_Functions\Euler angles.
3.5.2.4.7.8. Functions wm, wx, wy, wz
The functions return the magnitude (wm) and projections (wx, wy, wz) of a difference of angular velocities of SCA and SCB BA of a pair of bodies (angular velocity of body A relative to
body B), Figure 3.40. The projections are evaluated relative to the SC C.
Mathematical model
Velocity BA is evaluated according to the formula
BA  A  B
where  A , B are the angular velocities of SCA and SCB.
Function templates
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Chapter 3. Data input program
wm( _to_SC , [_from_SC] )
wx( _to_SC , [_from_SC] , [_SC_component] )
wy(_to_SC , [_from_SC] , [_SC_component] )
wz(_to_SC , [_from_SC] , [_SC_component] )
Arguments:
_to_SC: name of oriented point A;
_from_SC: name of oriented point B.
_SC_component: name of oriented point C.
Names of connection points include long names of bodies. As a rule, the name should be put
in quotes.
If point B is omitted, rotation of SCA relative to SC0 is considered.
If SC C is omitted, the projection is computed on axis of SC0.
Example
wx( "Car body.Local SC")
The function returns angular velocity of the Car body relative to the axis X of SC0.
wz("Bogie1.Frame.Local CK", "Car body.Local SC", "Car body.Local SC")
The function returns angular velocity of "Bogie1.Frame" relative to body “Car body”, projection on the axis Z of the local SC "Car body.Local SC".
3.5.2.4.7.9. Function incang
The function calculates the angle between two vectors BA and BC . The angle value lies in
the interval from 0 to . If one of the vectors is zero, the function returns zero value.
Mathematical model
 BA  BC 

  arccos 
 BA BC 

.
Function template
incang( _to_point1 , _from_point , _to_point2 )
Arguments
_to_point1 : name of connection point A;
_from_point2 : name of connection point B;
_to_point2 : name of connection point C;
Names of connection points include long names of bodies. As a rule, the name should be put
in quotes.
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3.5.2.4.7.10. Functions accm, accx, accy, accz
Functions return the magnitude (accm) or projections (accx, accy, accz) of vector a BA - the
acceleration of point A relative to SCB, Figure 3.41. Projections are calculated on axes of SCC
(not shown in the figure).
Mathematical model
Vector a BA is computed as
a BA  a A  a B  ε B  (rB  rA )  ωB  ωB  (rB  rA )  2ωB  v BA
where a A , a B are the accelerations of points A and B, ω B , ε B are the angular velocity and
acceleration of SCB, v BA is the velocity of point A relative to SCB.
Function templates
accm( _to_point , [_from_point] )
accx(_to_point , [_from_point] , [_SC_component] )
accy(_to_point , [_from_point], [_SC_component] )
accz(_to_point , [_from_point], [_SC_component] )
Arguments:
_to_point: name of connection point A;
_from_point: name of connection point B.
_SC_component: name of connection point C.
Names of connection points include long names of bodies. As a rule, the name should be put
in quotes.
If point B is omitted, acceleration of point A relative to SC0 is considered.
If SC C is omitted, the projection is computed on axis of SC0.
Remark.
These kinematic functions cannot be included in description of force elements.
3.5.2.4.7.11. Functions wdtm, wdtx, wdty, wdtz
Functions return the magnitude (wdtm) or projections (wdtx, wdty, wdtz) of vector ε BA - the
angular acceleration of SCA relative to SCB, Figure 3.41. Projections are calculated on axes of
SCC (not shown in the figure).
Mathematical model
Vector ε BA is computed as
ε BA  ε A  ε B  ω B  ω A
where  A ,  B are the angular accelerations of SCA and SCB, ω A , ω B are the angular velocities of SCA and SCB.
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Chapter 3. Data input program
Function templates
wdtm( _to_SC , [_from_SC] )
wdtx(_to_SC , [_from_SC], [_SC_component] )
wdty(_to_SC , [_from_SC], [_SC_component] )
wdtz(_to_SC , [_from_SC], [_SC_component] )
Arguments:
_to_SC: name of oriented point A;
_from_SC: name of oriented point B.
_SC_component: name of oriented point C.
Names of connection points include long names of bodies. As a rule, the name should be
written in quotes.
If point B is omitted, angular acceleration of SCA relative to SC0 is considered.
If SC C is omitted, the projection is computed on axis of SC0.
Remark.
These kinematic functions cannot be included in description of force elements.
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3.5.2.4.8. List of variables
List of variables is an efficient tool for development by the user of non-standard force interactions, surfaces, curves as well as kinematic variables evaluated during the object simulation.
List of variables is used by conversion of MSC.ADAMS models in UM format, Sect. 3.11.
Figure 3.43. List of variables in inspector
The Object | Variables tab is used for development of a list of variables, Figure 3.43. The
following buttons add and delete variables:
- add a new variable to the end of the list;
- delete selected variable;
- insert a new variable before the selected one.




A variable is an expression, which includes
numbers,
identifiers from the list of identifiers of the current model, Sect. 3.5.2.4.2, 3.5.3,
standard identifier of time t, arguments of scalar force x, v, parameter of a curve p, parameters of a surface p1, p2;
kinematic functions, Sect. 3.5.2.4.7;
variables from the current list;
standard functions and constants, Sect. 3.5.2.4.3
function Integral, Sect. 3.5.2.4.9.





The program determines the type of variable. Allowed types:
function of time, Sect. 3.5.2.4.6.1;
function x, v, t for use in description of scalar forces, Sect. 3.5.2.4.6.2;
kinematic functions, Sect. 3.5.2.4.7;
function of argument p for description of a curve, Sect. 3.5.2.4.6.3;
function of arguments p1, p2 for description of a surface, Sect. 3.5.2.4.6.4, 3.5.2.4.6.5.



The variables can be used by description of the following elements of the model:
forces listed in Sect. 3.5.2.4.7;
graphic objects, Sect. 3.6.8.2.7, 3.6.8.2.8;
contact surfaces (Z-Surfaces, Sect. 3.6.12.6.8) and curves (Sect. 3.6.7, 3.6.12.6.3).



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Remark.


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Chapter 3. Data input program
The user must avoid circling of variable description.
Examples of use of the variables:
control
force
in
the
model
of
inverted
pendulum,
the
model
{UM Data}\SAMPLES\LIBRARY\Variables and Kinematic functions\Inverted pendulum
UM;
plots of kinematic variables by simulation, the models;
{UM Data}\SAMPLES\LIBRARY\Variables_and_Kinematic_Functions\Yaw Pitch Roll;
{UM Data}\SAMPLES\LIBRARY\Variables_and_Kinematic_Functions\Euler angles.
3.5.2.4.9. Integral function and adding differential equations
The Integral function allows the user to specify additional ordinary differential equations
(ODE)
dy
 f (t , y,...)
dt
.
Format of the corresponding variable in the list of variables is as follows, Sect. 3.5.2.4.8:
[Name of variable], Integral(f(t,[Name of variable],…)).
Arguments of the right hand side of the equations f are
 t,
 the variable itself,
 any variable in the list, which type is a kinematic variable or an integral.
Therefore, the user can specify both a single ODE, and a system of ODE.
Additional differential equations specified by the user are solved together with equations of
motion of the model. To make this process compatible, the first order ODE is replaced by the
equivalent second order ODE
d 2z
dz
dt .
dt 2
Initial values for additional variables are specified in the standard manner. It is important to
know that the initial value y(0) correspond to the velocity value in the table of initial conditions.
 f (t , y,...), y 
Examples.
1. ODE
dy
 y
dt
is specified by the variable V1 in Figure 3.44. In this example the variable name is V1, and
the parameter α is set by the identifier alpha.
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Chapter 3. Data input program
Figure 3.44. Variable as a solution of differential equation
2.
Example of a variable, which is an integral of an rotations angle in a joint, is shown in Figure 3.43, see the model {UM Data}\SAMPLES\LIBRARY\Variables and Kinematic functions\Inverted pendulum UM;
3.
Simplified model of a direct current motor
Consider a simplified linear model of a direct current motor
dI
L
 U  RI  C,
dt
M  CI
Here L, R are the inductance and the active coil resistance, I is the current in the armature
coil, U is the voltage, M is the torque on the motor shaft,  is the shaft angular velocity, C is motor constant. The implementation of the model as a list of variables is shown in Figure 3.45. It is
supposed that the shaft angular velocity is equal the angular velocity in joint jBody1. The torque
is computed as the variable of the same name and must be applied to the shaft as the joint torque.
Figure 3.45. Implementation of the motor model
Remark.
Use of arguments of a scalar force x, v is not allowed in the differential equations. The corresponding kinematic variables must be applied instead,
Sect. 3.5.2.4.8. For instance, if x and v are the joint coordinate and its time derivative, the coordinate function is recommended, Sect. 3.5.2.4.7.1.
3.5.2.4.10. External functions
Using external function is directly connected with programming in the UM environment
based on a Control file. As a rule, these functions are used when the corresponding mathematical
model is too complicated for description as an implicit function (Sect. 3.5.2.4.6).
Using external functions requires generation of equations of motion in symbolic form as
well as external compiling the equations, Sect 3.9.2.
There exist three types of external functions, which differ in arguments.
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Chapter 3. Data input program
1.
Time functions (t) are used for joint of generalized type, elementary transformation of types
tt,rt (Sect. 3.6.11.7.4) as well as for rotational and translational joints in the cases when the
joint coordinate is an explicit function of time (Sect. 3.6.11.4).
2.
Functions of three arguments (x, v, t) are used for description of scalar force of external
type; Sect. 3.6.12.2.8. The list of the corresponding force elements is
Bipolar force element; x is the length of the element; v is the time derivative of the length,
Sect. 3.6.12.3;
Scalar torque; x is the rotation angle; v is the time derivative of the angle, Sect. 3.6.12.4;
Joint forces in the case of joint of general type (elementary transformations rv, tv, type of
force is expression, Sect. 3.6.11.7.3, as well as for translational and rotational joints,
Sect. 3.6.11.4; x is the value of coordinate, v is its time derivative;
Description of an axle force in the case of a special force of the Combined friction type;
Components of bushing force elements of the generalized type, Sect. 3.6.12.8.6.2.





3.
Function of two arguments (p1, p2) are used for description of Z-surfaces (surfaces given by
the function z = f(x, y)) in the cases of graphic element (type - Z-surfaces) (Sect. 3.6.8.2.9)
and contact forces (Z-sphere).
To describe an external function, the user should enter its name (identifier) in the corresponding edit box of the inspector without arguments, for instance,
Syntax rules for name of function as the same as for identifier (Sect. 3.5.2.4.2).
UM generates a template for each external function in the control file. This means, that special functions will be added to the control file, where the external function will be initialized by
zero values. The user should rewrite the corresponding procedures.
Consider a template of a time function. Let the identifier alpha be used as the name of an external function. UM inserts the following procedure in the control file Cl[IdentifierOfObject]:
procedure alpha( _isubs : integer; _t : real; var _Value, _dValue, _ddValue : real_ );
var
_ : _platfVarPtr;
begin
_ := _PzAll[SubIndx[_isubs]];
_Value := 0;
_dValue := 0;
_ddValue := 0;
end;
The input parameters are _isubs (the global index of subsystem), _t – the current time value.
The output: value of function (identifier _Value) as well as its first and second derivatives
(_dValue, _ddValue).
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Wrong programming of derivatives leads to wrong simulation results.
Consider a template for a function of (t, x, v). Let the identifier bforce1 was used for external
function corresponding to a scalar force. UM inserts the following function in the control file
Cl[IdentifierOfObject]:
function bforce1( _isubs : integer; _t, _x, v : real ) : real_;
var
_ : _vehicleVarPtr;
begin
_ := _PzAll[SubIndx[_isubs]];
Result := 0;
end;
The input parameters are _isubs (the global index of subsystem), _t is the current time value,
_x, _v are the current x and v values. The user should change the function code to calculate the
output value Result.
Remarks
1. External functions require generation of equations of motion in the symbolic form. In the
case of numeric-iterative generation of equations, an error is detected.
2. Functions of the one and same type, which have coinciding identifiers, are identified. That
is, only one template of function or procedure will be generated for them in the control file.
Different identifiers must be used for external functions of different types.
3. Detailed information about the control file and programming in the UM environment can be
found in Chapter 5 of the user’s manual.
4. The Simulation program calls external functions automatically.
5. After adding or deleting external functions, the user should verify the correctness of the old
control file.
3.5.2.4.11. Time function using text file
Here we consider how to set dependences on time of angular and translational coordinates
with the help of text files. The file can contain both full-scale test and simulation results.
Coordinates as time functions are realized in the following joints
 generalized joint, elementary transformations tt, rt (3.6.11.7.4);
 translational and rotational joints when the coordinate is a time function (3.6.11.4).
Format of a text file
A text file with a time function should contain two columns separated by space symbols. The
first column contains time in seconds starting with zero or a small value. The second column
contains the corresponding values of the function in meters for a translational coordinate and in
radians for an angular coordinate.
First symbol in comment lines should be %.
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Chapter 3. Data input program
The file should be created beforehand and located in the directory of the model, which uses
it.
If UM does not find the file, zero value is set for the corresponding function.
Creation of files with a time function as a simulation result
Each plot in graphic windows can be saved in a text file after simulation of a UM model
(Chapter 4, Sect. Graphical window | Copying graphs to clipboard, text file and file of calculated variables). The file format matches the above requirements if
 % symbol is set as a prefix for comments (Chapter 4. Sect. Options of simulation program |
General), otherwise comments should be deleted from file manually;
 one variable is saved;
 time is laid off as abscissa.
Fragment of an automatically generated compatible text file with a time function:
%
% 1 - time
% 2 - dyWheelset4 [Lateral position of Wheelset4]
%
2.00000002337219E-7 2.82372854E-15
1.03125004097819E-2 2.03257468E-6
2.09375005215406E-2 7.46718570E-6
3.21874991059303E-2 1.76279409E-5
4.21875007450581E-2 3.07774899E-5
Standard interface for setting the file
Figure 3.46. Time function from file
To set the name of the file, use the
Note 1.
Note 2.
Note 3.
button or write the name directly.
UM uses a spline interpolation of discrete file data to get function value in intermediate time moments as well to compute the first and the second derivative,
which are necessary for simulation.
The user should take care of a sufficient smoothness of data in file.
When the current simulation time exceeds the latest time point in the file, the
function value is constant equal the latest one in the file.
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Chapter 3. Data input program
3.5.2.4.12. Timetable as a method of description of time functions
Figure 3.47. Example of a timetable function
Timetable is a generalization of time function description by an expression. This method is
used if the function can be described by different symbolic expressions on several time intervals.
For instance, the function in Figure 3.47 satisfies the following relations:
vt, t  [0, t1 ]

f (t )  
vt1 cos((t  t1 )), t  t[1 , t2 ]
A standard interface is used for setting such dependencies:
Figure 3.48. Interface for timetable
Use a pop-up menu to add, delete insert a line into the timetable, Figure 3.48. The Plot item
is used for plotting the functions.
The table can contain any number of lines.
Time in the left column can be set by expressions (identifiers t1, t2 in our example).
Note 1.
Note 2.
The user should take care of a continuity of the function.
When the current simulation time exceeds the latest time point in the timetable,
the function value is constant equal to the latest one in the table.
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Chapter 3. Data input program
3.5.2.4.13. Expression editor
A special editor can be used for writing long expressions. To call the editor, double click on
the edit box with the expression. Figure 3.49 shows edit boxes for description of a surface by
parametric expressions (a) and the content of one of the boxes in the editor (b).
a
b
Figure 3.49. Edit box (a) and expression editor (b)
Figure 3.50. Selection of available elements of expressions
Depending on the expression type, the editor organizes access to data, variables and functions. In the most general case the following lists are available in the right part of the window:
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Chapter 3. Data input program
Identifier
List of object identifiers, Sect. 3.5.3.
Standard functions
List of the standard functions, Sect. 3.5.2.4.3.
Kinematic functions
List of kinematic functions, Sect. 3.5.2.4.7.
Variables
List of variables created by the user, Sect. 3.5.2.4.8.
Points
List of connection points for all of the bodies, including simple points, vectors and oriented
points, Sect. 3.6.9.6.
Oriented points
List of all oriented points assigned to bodies, Sect. 3.6.9.6.2.
Joints
List of joints, Sect. 3.6.11.
Double click of an element of a list adds the element or function template to the expression in
the cursor position.
Remark 1.
Remark 2.
The Points, Oriented points and Joints lists contain all elements in the object including subsystems. Lists of identifiers and variables do not include elements
from subsystems
Names of elements containing non-standard symbols like a space must be put in
quotes.
The Check button calls syntax analysis of the expression. The Cancel button closes the editor without saving modifications in the expression.
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Chapter 3. Data input program
3.5.3. List of identifiers
A list of identifiers is the main tool of parameterization of UM models, Sect. 3.5.2.4.2.
3.5.3.1. Window with list of identifiers
Window with the list of identifiers is intended for creation and modification of identifiers,
changing numeric values and expressions.
Figure 3.51. Sheets of the list of identifiers
3.5.3.2. Modification of identifiers
The tool panel contains a number of buttons with the following functions.
Adding a new identifier, Figure 3.52. Hot key: Insert.
Editing selected identifier, Figure 3.52. Hot key: Enter; mouse: double click.
Deleting selected identifier. After deleting the identifier in expressions is replaced by its
current numeric value.
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Chapter 3. Data input program
Renaming identifiers is possible in the editor window, Figure 3.52. The new name replaces
automatically the old one throughout in the model.
Figure 3.52. Adding and modifying an identifier
Changing values of identifiers of the same name in subsystems
If the user changes the value of an identifier and subsystems of the model have identifiers of
the same name, a special window with the list of these identifiers appears, Figure 3.53. The user
may assign the new value to the selected identifiers from the list. In the case shown in Figure 3.53, the new value 82000 will be assigned to all identifiers.
Figure 3.53. Example of a list of identifiers of the same name
See Sect. 3.5.3.5.
3.5.3.3. Identifier sheets
A sheet is a group of selected identifiers. The sheets are used for logical separation of the
identifiers into groups, e.g. inertial, geometrical parameters, suspension parameters etc.
Control buttons for managing the sheets:
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Chapter 3. Data input program
Adding a new sheet.
Renaming the current sheet.
Modification of the current identifier group. The tool allows adding and removing identifiers with the special dual window. In particular, double clicks are used for adding/removing
identifiers.
Deleting the current sheet.
3.5.3.4. Object refresh after change of identifier value
The button
switches the modes of immediate/postponed refresh of the object elements
after change of numeric value of an identifier. The refresh is recommended to be postponed if it
is made too slow in case of large models.
3.5.3.5. Pop-up menu of identifier list
Figure 3.54. Commands of pop-up menu of identifier list
The pop-up menu appears after click of the right mouse button on the list of identifiers, Figure 3.54. The menu contains the following commands.
 New identifier: the command opens the window for editing identifiers, Figure 3.51, and
adds the new identifier to the end of the list.
 Add from subsystem: if subsystems are presented in the current UM object, the command
opens a window with the list of identifiers included in subsystems (Figure 3.55) and allows
the user to add identifiers in the current list by clicking on the desired identifiers in the window by the left mouse button. The command is often used to add to the main object identifiers from subsystems, which values are frequently changed during the simulation. In such the
way the process of access to identifiers is simplified.
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Chapter 3. Data input program
Figure 3.55. Example of identifier tree





Insert identifier: the command inserts a new identifier immediately before the line corresponding to the position of the mouse cursor.
Edit identifier: the command opens the window for editing the identifier in the position of
the mouse cursor, Figure 3.51.
Delete identifier: the command deletes an identifier in the position of the mouse cursor.
Copy value to clipboard: the command copies to clipboard the value of the identifier in the
position of the mouse cursor.
Copy table to clipboard: the command copies to clipboard as text all identifiers from the
current sheet. Example:
Name
m_bus
ixx_bus
izz_bus

Expression
Value
1.5000000E+4
1.0000000E+4
2.5000000E+5
Comments
Mass
Moment of inertia
Show elements including identifier: the command opens a window with the list of elements, which includes the identifier in the position of the mouse cursor, Figure 3.55. The
user opens the element in inspector by clicking on the element name in the list.
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Chapter 3. Data input program
Figure 3.56. Example: list of elements including identifier r_Wheel

List of unused identifiers: the command opens a window with the list of identifiers, which
are not used in description of object elements, Figure 3.57. In particular, this window is used
for deleting some of unused identifiers: the checked identifiers are deleted by the Delete
button in the bottom of the window.
Figure 3.57. Example of unused identifiers



New sheet, Rename sheet, Modify identifier group, Delete sheet: the commands manage
the identifier sheets, Sect. 3.5.3.3.
Delete from sheet: the command removes an identifier located under the mouse cursor
from the current sheet.
Refresh: the command refresh the object, Sect. 3.5.3.4.
3.5.3.6. Adding new identifiers by element description
The user may add new identifiers directly during description of any model parameters and elements like inertia parameters, force elements and so on, Figure 3.58.
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Chapter 3. Data input program
Figure 3.58. Example of adding new identifiers by description of expression
By analysis of expression the program detects new identifiers and suggests the user to assign
numeric values and comments to the identifiers in a special window. If necessary, the new identifiers can be placed on one of the existing sheets or on a new sheet, Sect. 3.5.3.3. The list “Add to
the sheet” is used for selection of existing sheet. Write the name of a new sheet in the same edit
box to place the identifier in a new created sheet.
3.5.3.7. Jump to identifier from the element parameter
If an identifier is used by description of a parameter of the object, the user can find it in the
list of identifiers. To find the identifier, click the right mouse button on the edit box and select
the Find identifier commend of the pop-up menu, Figure 3.59. The identifier will be selected in
the list.
The function is useful in the case of large lists of identifiers.
Figure 3.59. Example of jump to the identifier M_Frame
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Chapter 3. Data input program
3.5.4. 2D curve editor
Tool bar
Type of smoothing
Curve
List of points
Figure 3.60. Curve editor and its elements
2D curve editor is a tool for input of data in a graphic form. The editor allows the user to create a plane curve, a function or a set of curves by a set of points. Here we consider some features
of working with the editor. Additional information about usage of this tool for creation of 2D
graphic images can be found in Sect.3.6.8.6.
3.5.4.1. Modes of curve editor





There exist two modes of the editor depending on the problem to be solved.
Mode of creation of a set of curves
Mode of creation of a function
The second mode imposes a number of restrictions and additional features:
one curve only;
ordering points according to abscissa value;
plots the first and second derivative as well as a curvature in a separate window is available.
3.5.4.2. Tool bar
Consider functions of buttons on the tool bar. Note that sets of buttons differ for different
modes of the editor.
left shift depending on the mouse button;
right shift depending on the mouse button;
- popup /fixed panel;
- copy to clipboard;
- zoom in by frame;
- select curve sections by frame;
- show all;
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Chapter 3. Data input program
- settings;
- add new point;
- insert new point;
- delete selected points;
- read data from file;
- save data to file;
- paste;
- tangent and curvature (1st derivative, 2nd derivative, curvature, smoothed curvature);
- list of identifiers (Figure 3.61).
Figure 3.61. Window of model parameters
3.5.4.3. Adding, positioning, and deleting separate point on a curve
There exist two methods for adding a point to a curve.
1. Double click by the left mouse button in the position of the adding point.
With this method a point can be added both to begin and the end of a non-closed curve, as
well as inside the closed or non-closed curve. When a point is added to the beginning or to the
end of a curve, it is recommended to put it near the corresponding first or last point of the curve
and then to drag it to the desirable position.
2.
Button
in the top of the list of points (Figure 3.60).
With this method you can add point to the end of the curve only.
Positioning the point means setting its desirable position. Two methods are realized for this
purpose.
1. Positioning by the list of points.
Find the point in the list, e.g. by clicking on its image in the plot area, and set its new coordinates.
2. Positioning by dragging.
This is the most often used method for approximate positioning points. Move the mouse cursor near the point image. The cursor must change to
point to the desirable position.
. Press the left mouse button and drag the
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To delete a point, either select it in the list of point and click the
mouse cursor near the point image until it changes to
right mouse button and select the Delete menu item.
button, or move the
, call the pop-up menu by clicking the
3.5.4.4. Selecting, copying, deleting and moving fragments and curves
To select a fragment (a set or points) draw a rectangle region in the plot area by dragging the
mouse cursor (Figure 3.62).
Figure 3.62. Fragment selection by mouse
There exist to methods for the selection of a curve.
1. Select the name of a curve in the list of curves (Figure 3.63).
Figure 3.63. Selection of a curve in the list of curves
2.
Move the mouse cursor near the curve until it changes to , call the pop-up menu by the
right mouse button and select the Select whole curve menu item.
To select all points call the pop-up menu and select the Select all menu item.
To remove a selection, click by the left mouse button anywhere outside the selection rectan-
gle.
To move a fragment or a curve, select it, move the mouse cursor until it changes to ,
press the left mouse button and drag the fragment. Moving a fragment is forbidden in the mode
of creation of a function.
To delete a fragment or a curve, select it and press the Delete key.
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To copy a fragment or a curve select it, press the Ctrl+C and Ctrl+V hot keys, and move
the copied fragment into a desirable position.
3.5.4.5. Closing curve
Two methods of closing a curve:
1. move one of the curve end point by the mouse to a small neighborhood of the another end;
2. use the
key in the top of the list of points.
3.5.4.6. Smoothing
To smooth a curve or a fragment, select it and choose one of the smoothing type from the list
(Figure 3.60)
3.5.4.7. Using the clipboard for creating curves and functions
For input from the clipboard, points should be written as a text in two columns. The first column contains abscissa values, the second one corresponds to the ordinate values
-68.9
11.7
-66.4
8.88
-63.9
6.98
-61.4
6.48
-58.9
5.99
…….
To get points from the clipboard
 Copy the new data to the clipboard from any text editor in a standard manner;
 Activate the curve editor by the mouse and paste data from the clipboard (Ctrl+V or
Shift+Insert).
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3.5.5. Hot keys
3.5.5.1. Constructor hot keys



Ctrl+Alt+X – make the tree of elements active, Sect. 3.5.1.1;
F11 – bring to front the list of elements (if it is located as a separate window);
F12 – bring to front the data inspector (if it is located as a separate window).
3.5.5.2. Inspector hot keys















Open element data (a tab of the constructor):
Ctrl+Alt+O – object;
Ctrl+Alt+S – subsystems;
Ctrl+Alt+B – bodies;
Ctrl+Alt+G – graphic objects;
Ctrl+Alt+J – joints;
Ctrl+Alt+F – bipolar forces;
Ctrl+Alt+M – scalar torques;
Ctrl+Alt+L – linear forces;
Ctrl+Alt+C – contact forces;
Ctrl+Alt+T – T-forces;
Ctrl+Alt+A – special forces;
Ctrl+Alt+Z – external connections;
Ctrl+Alt+I – indices;
Ctrl+Alt+P – protocol;
Ctrl+Alt+R – coordinates.
3.5.5.3. Animation window hot keys
In the mode of element selection by the mouse button (the button
must be down,
Sect. 3.5.1.2.4), mouse move over a body image allows the user to get coordinates of the corresponding points of the body relative to SC0. If the Shift key is pressed, the coordinates will be
given in the body-fixed SC. If the Ctrl key is pressed, the coordinates of body-fixed SC origin in
SC0 are shown.
3.5.5.4. Inspector tab with a list
Ctrl+Alt+GrayPlus – add element;
Ctrl+Alt+GrayMinus – delete the current element;
Ctrl+Alt+Gray* – copy the current element;
Ctrl+Alt+N – edit name.
For elements connecting a pair of bodies (joints, force elements):
Ctrl+Alt+1 – choose the first body from the list of bodies;
Ctrl+Alt+2 – choose the second body from the list of bodies;
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3.6. Data Input
3.6.1. Data Input Sequence
The following sequence of object data input is recommended.
1.
External and/or included subsystems, if UM Subsystems module is available, Sect. 3.6.3.
It is recommended to use subsystems for development of complex models. Structuring a
model as a tree of subsystems is efficient for simulation of rail vehicles, trains, and tracked vehicles.
2.
Bodies, their graphical images and the corresponding joints.
The sequence of description of bodies is usually defined by the kinematical scheme of the
object. At first, the bodies connected with the base body (Base0, SC0) as well as the corresponding joints are described, and then the bodies connected with already described bodies and so on.
By such description the sequence of kinematic scheme of object all its bodies are drawn not only
in the single element mode of animation window but also in the whole object mode of the animation window (Sect. 3.5.1.2.2). It is important to remember, that in the mode of whole object animation, the described body is drawn in the animation window if there exists a path from the current body to the base body through the described joints.
3.
Force elements and their graphical images
After describing the object kinematical scheme, force element images are drawn in the animation window both in the current element and the full object animation mode, which allows the
user to control geometrical parameters of force elements visually.
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3.6.2. Methods for adding elements to object
3.6.2.1. Direct creation of single element
A direct creation of an element such as subsystem, graphic object, body, joint, bipolar force
and so on with the help of the standard interface of element lists is considered in Sect. 3.5.2.2.
3.6.2.2. Adding elements by visual components
Figure 3.64. Tabs with visual components
Lists of components give an effective tool for visual adding some of elements, Figure 3.64.
The method is described in Sect. 3.7.2.
3.6.2.3. Main menu commands for adding a typed element
A type element is an element with assigned type. The typed element can be added by the
Add menu command, Figure 3.65.
Figure 3.65. Adding a typed element by menu command
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3.6.2.4. Adding typed elements by pop-up menu of element tree


In this case,
select the root item of element list in the element tree (e.g. Images),
call a pop-up menu by the right mouse button and select the desired command, Figure 3.66.
Figure 3.66. Adding typed element from element tree
The same result is obtained by the main menu command Add, Sect. 3.6.2.3.
3.6.2.5. Insert of element from other model by clipboard





The following steps are required:
open the model, which element must be copied;
select the element in the element tree;
copy the element in the clipboard by
a) Edit | Copy to clipboard menu command or by the button on the tool panel if no image of the element must be copied;
b) Edit | To clipboard as component menu command or by the
button on the tool panel
to copy both the element and the image assigned to it;
make active the model for adding the element and run the Edit | Insect menu command or
click on the
button on the tool panel;
if necessary, correct numeric values of identifiers added together with the element.
3.6.2.6. Insert of element from other model by file



The following steps are required:
open the model, which element must be copied;
select the element in the element tree;
copy the element in a file by
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a) Edit | Copy to file menu command or by the
button on the tool panel, if no image of
the element must be copied;
b) Edit | Save as component menu command or by the
button on the tool panel to copy
both the element and the image assigned to it;
make active the model for adding the element and run the Edit | Read from file menu
command or click on the button on the tool panel;
if necessary, correct numeric values of identifiers added together with the element.
3.6.2.7. Merging models



One model can be completely included into another one:
open the model to be included and save it to a file with any name and extension by the File |
Save as component menu command or by the
button;
open the model which will include the first one;
read the saved file by the Edit | Read from file menu command or by the button.
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3.6.3. Subsystems
Subsystems give a powerful tool for development of complex models such as rail vehicle,
train, articulated truck and so on, see Chapter 2, Sect. Subsystems. In particular, flexible bodies
are added to a model as subsystems.
Subsystems are available if the UM Subsystems module is included in the configuration. To
verify whether the module is presented in the current UM version, use the menu command Help |
About…, Figure 3.67.
Figure 3.67. List of modules included in the current UM configuration
3.6.3.1. Adding a subsystem
Figure 3.68. Selection of subsystem type
Subsystem list management buttons are, Figure 3.68
– create a subsystem;
– copy an existing subsystem;
– delete a current subsystem.
There are three types of subsystems: included, external and special.
Special subsystems such as wheelset, FEM subsystem and Caterpillar are used in UM modules UM Loco, UM FEM and UM Tracked vehicle respectively. Working with special subsystems is described in details in the corresponding parts of the user’s manual. Here we consider
included and external subsystems only.
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After choice of the subsystem type (included or external) the user must open an UM object
which will be included as a subsystem in the current object.
Main parameters of external and included subsystems are almost the same, Figure 3.69. They
are name, comments, position of the subsystem (Sect. 3.6.4), list of identifiers used in the subsystem (Sect. 3.5.3), and the identifier of the subsystem used for programming. Also an external
subsystem has one more parameter Ancestor (Figure 3.69b), which is the path to the folder with
ancestor of the subsystem. To convert an external subsystem to an included one, click the button
Convert to include on the tab General.
a
b
c
d
Figure 3.69. Tabs of the object inspector for subsystems: a) General tab for included subsystem;
b) General tab for external subsystem; c) Position tab, d) Identifier tab.
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3.6.3.2. Transformation of model into subsystem


The transformation of the model into subsystem is used
by development of a model as a tree of subsystems;
by development of a component, which must be added to the model as a subsystem (example: suspension subsystems of tracked vehicle, see 18_UM_Caterpillar.pdf).
To transform the model into a subsystem, open the Object tab of the inspector and click on
the Transform into subsystem button, Figure 3.70. After the transformation, all elements will
be removed from the model. Thereby, the model will include only one subsystem, which content
is identical to the model before the transformations.
Figure 3.70. Transformation button
3.6.3.3. Interconnection of subsystem. Use of external elements
Joints and force elements can connect bodies of different subsystems by two different ways:
1. the element (joint, force element) is created in the head object; one or two bodies from the
subsystems are assigned to it;
2. external elements described in the subsystem are used, Sect. 3.6.10.1.
3.6.3.3.1. External elements. Autodetection
External element is a joint or a force element described in a subsystem, which second body
is External, Figure 3.71. This means that the second body belongs to either another subsystem
or to the ‘upper’ object. Use of external elements is the base for rapid development of an object
as a tree of subsystems.
The second body is assigned in an upper subsystem or in a head object with the help of connection points, Sect. 3.6.3.3.2.
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Figure 3.71. Example of an external element
Remark 1.
Remark 2.
External elements are ignored if the second body is not assigned.
Method of a fictitious body is recommended instead of use of external joints,
Sect. 3.6.3.3.3.
Autodetection mode of elements allows a significant simplification and acceleration of
working with external elements. If the autodetection mode is on (Figure 3.71), the coordinates of
the attachment point for the second body are set in the SC of the first body for zero values of all
object coordinates. Thereby, the coordinates of the second attachment point can be defined in
the subsystem, in which the external element is described.
Consider a damper connecting an axle box and a frame, Figure 3.72. The damper is described
in a subsystem, which does not include the frame, and the second body is the External one. The
autodetection mode is on, and the coordinates of the second (upper) end of the element are specified in the SC of the axle box. As a result, the coordinates of this point in SC of the frame will be
computed automatically.
Figure 3.72. Example of an external element with the autodetection mode
3.6.3.3.2. Assignment of second bodies to external elements
The Connections tab of the inspector is used for assignment of second bodies to external elements, Figure 3.72. The tab includes the list of external elements included in subsystem tree,
Figure 3.73. If second bodies are already assigned to some external elements in subsystems, such
the elements are excluded from the list.
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Figure 3.73. Example of external elements. Second bodies are not assigned
Figure 3.74. Example of external elements. Second bodies are assigned
The following methods are used for assignment of the second bodies to external elements.
1.


External element without autodetection
A connection point must be preliminary defined for the body, which will be assigned as the
second body to the external element, Sect. 3.6.9.6. Coordinates of this point correspond to
the attachment point of the element.
Select the external element in the list. If a graphic image is assigned to the element, it is selected in the animation window. For visual assignment of the connection, click by the
mouse on the point image, Figure 3.75. For selection of a point from the list, double click on
the element name or run the Assign point command of the pop-up menu, Figure 3.76. The
list of connection points replaces the list of external elements, Figure 3.77. Assign the point
by the mouse click.
Figure 3.75. Yellow points mark connection points
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Figure 3.76. Pop-up menu of the list of external elements
Figure 3.77. List of connection points
2.
External element with autodetection
Advances in use of external elements with autodetection consist in fact that any connection
point of the necessary body can be assigned to the element, because the coordinates of the attachment point are computed automatically according to data specified in the subsystem. As a
result, only one connection point is necessary for assignment of any number of external elements
to a body. The assignment process in this case is quite similar to that described above for an element without autodetection.
In a particular case when autodetection is set for all external elements and all the elements
are connected with the same second body, the Assign to all menu command is highly efficient,
Figure 3.76. In this case, all external connections are assigned by one operation!
Remark.
An external element is ignored if the second body is not assigned.
3.6.3.3.3. Using fictitious body instead of external elements
A fictitious body is an alternative to external elements in the case of included subsystems.
The following method is recommended.
1.
An additional body with six degrees of freedom is added to the model by the
button. The
body model is this case contains an internal joint, Sect. 3.6.9.3, Figure 3.78. Inertia parameters of the body are zeroes.
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Figure 3.78. Body with internal joint
2.
3.
All external elements are connected to this body.
In the upper subsystem or in the head object, the fictitious body is rigidly connected to the
necessary body by a joint with zero degrees of freedom. It is recommended to use a generalized joint with one elementary transformation of the type tc (translation, constant), Figure 3.79, or a 6 d.o.f. joint with disabled coordinates. If necessary, additional rotation is introduced by elementary transformation of the type rc or rt. Translation and rotation allows a
correct positioning of the fictitious body relative to the corresponding body.
After the fictitious body is connected to the external body, the internal joint with six degrees
of freedom is automatically removed (ignored).
Figure 3.79. Joint rigidly connecting a frame with a fictitious body
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Fictitious bodies are successfully used, e.g., in the module UM Tracked Vehicle.
3.6.4. Standard interface for setting local system of coordinates
B
2
O
1
A
Figure 3.80. Setting position of local SC
The interface allows the user to define a fully parameterized position of a local system of coordinates (LSC) relative to SC of a body, a graphic object or a graphic element. Consider a SC
with an origin in point O (SCO). It is necessary to define the position of SCB relative to SCO.
First, an auxiliary SC with the origin in point A (SCA) is introduced, which position relative
to SCO is set by the shift vector 1 and by a set of up to three sequential rotations. After that the
position of point B relative to SCA is specified by the vector  2 . Thus, axis of SCA and SCB
are parallel. In particular case 2  0 and SCB coincides with SCA.
The auxiliary SCA is sometimes useful when shifts could be specified simpler relative to already rotated exes, i.e. relative to SCA.
Figure 3.81. Window for specifying an LSC
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The standard interface for setting LSC is shown in Figure 3.81. Data are entered in three
groups.
- Translation. Projections of vector 1 in SCO are entered.
- Rotation. Sequence of rotations specifies orientation of SCA and SCB relative to SCO. It is
allowed up to three rotations. Angles of rotation are set here in degrees.
- Shift after rotation. Projections of vector  2 in SCA are entered, i.e. shifts along axes of
SCA.
Both projections of vectors and angles of rotation can be parameterized.







The interface is used for input of the following data types.
Position of a subsystem, Sect. 3.6.3.1.
Position of local SC of a curve, Sect. 3.6.7.
Position of a graphic object, Sect. 3.6.8.1.
Position of a graphic element relative to SC of graphic object, Sect. 3.6.8.4.
Setting local SC for special force element of the “Bushing” type, Sect. 3.6.12.8.6.
Setting local SC for scalar torques, Sect. 3.6.12.3.
Setting local SC for 6 d.o.f. joint, Sect. 3.6.11.6.
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3.6.5. Assigning Graphical Image to Object Element
Graphical images (graphical objects, GOs) can be assigned to the most of UM elements, for
example, to the scene, bodies, some kinds of joints (e.g. a rod), some kinds of force elements
(bipolar, linear) and so on. Clicking on a graphical image of element by mouse, the user can
open the element description in the object inspector. For this purpose the whole object animation
mode must be set in the animation window (Sect.3.5.1.2.2).
Remark.
Visual operations with the mouse in animation window are available if the button
on the tool panel is set to the ‘down’ state.
Graphical image is assigned to an object element from the list of the previously described
GOs using a drop-down list in the inspector of the current element (body, for example).
Figure 3.82. Assignment of a GO
The drop-down list contains names of GOs, which have been set by the user while describing
graphical objects or by default. To make choosing a GO easier, it is recommended to give sensible names to GOs (Figure 3.82).
Activate the corresponding drop-down list and press the Delete key to cancel the assignment
of a GO to the element.
There are some features by assigning GO to the object element.
GO can be assigned to each of the bodies; the same GO may correspond to several bodies
(this is the main principle). The GO system of coordinate is automatically superposed with the
SC of the corresponding body. All elements of mechanical system, which are fixed relative to the
base SC0 (e.g. plane supporting a rolling ball, obstacles etc.), can be presented by a single GO,
which is assigned to the scene image on the Object | General inspector tab, the parameter Scene
image. The scene image can be assigned to the body Ground as well, Sect. 3.6.9.7.
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3.6.6. Assignment of graphic images to rods, linear and bipolar force
elements
A GO can also be assigned to a linear or bipolar force element (Sect. 3.6.12.3, 3.6.12.1) or to
a weightless rod constraint (Sect. 3.6.11.9). These elements link two points of different bodies.
UM automatically puts the assigned GO between the points. There is an obligatory condition
while creating such a GO: a GO corresponding to a linear or bipolar force element or to a rod
constraint must be located along the Z axis of the SC GO.
Consider two methods for development of GO.
1. Simplified
In this case the button
must be in the ‘up’ state. The program puts the point (0, 0, 0) of
GO to the first attachment point to the first body, and the point (0,0,1) is put to the second attachment point. Usually, the total length of the GO must be 1m. The GO is stretched or compressed according to the real length of the element, Figure 3.83.
Figure 3.83. Examples of simplified images of a cylindrical spring and a damper. The length of
images is 1m
2.
An advanced method allows escaping stretching or compressions of some parts of GO,
Figure 3.84.
Figure 3.84. Example of an advanced image of a shock absorber
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In this case, the button
state must be ‘down’. Drawing of the image depends on the parameters in the Bipolar GO tab: Length, Bottom, Top, Figure 3.85.
Figure 3.85. Parameters of a bipolar GO
The program locates the image in such a way that the point (0,0, Bottom) of GO is set into
the first attachment point, and the point (0,0,Top) of GO coincides with the second body point.
Orientation and length of the image is computed respectively. Thus, in spite of the image is oriented along the Z axis in SC GO, an arbitrary orientation of the element in the model can be obtained.
Use the
key to prohibit the stretching some of the graphic elements included in
the image. In this case the
key indicates the position of the element in the top or in the
bottom part of the image.
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3.6.7. Input of 3D curves
3D curves are used in the point-curve contact element, Sect. 3.6.12.6.3, Chapter 2,
Sect. Point-Curve contact.
In general, the curve equation is the dependence of the radius-vector on the scalar parameter
p in some SC as
  ( p), p  [ pmin , pmax ] ,
The same curve in a scalar form is set by three relations
x  x( p), y  y ( p ), z  z ( p ),
( p )  ( x( p ), y ( p), z ( p))T



The following types of 3D curves are considered:
( pmin )  ( pmax ) ;
open curve, which end points differ,
( pmin )  ( pmax )
closed curve with equal end points,
;
periodic curve is a closed curve, which have smooth derivative at the end points (tangents
( pmin )  ( pmax ) ; the stroke here corresponds to derivative with respect to the
coincide)
parameter p.
a
b
c
Figure 3.86. Curves of different types
Figure 3.86 shows an open (a), closed (b) and periodic (c) curves.
If the curve is used in the contact element, each of the two end points of an open curve can be
either locking or unlocking. The locking end point keeps the contact point on the curve, while the
contact disappears by passing through the unlocking point.



Three methods are used for description of curves in UM:
analytic expressions; elements of list of variables can be used in the expressions,
Sect. 3.5.2.4.6.3;
plane pointwise curve;
3D pointwise curve.
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3.6.7.1. Adding new curve
Figure 3.87. New curve
To create a new curve, open the curve editor in the inspector by the Object | Curves item of
the element tree and add a curve by the



button, Figure 3.87.
Type of curve
Select one of the three types of curve in the drop-down menu:
Expression
Points 2D
Points 3D
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Local SC of curve
Curve
Main SC of curve
Figure 3.88. Systems of coordinates related to curve
Main and local SC of curve
Two systems of coordinates are related to a curve, Figure 3.88:
- main SC of curve will coincide with SC of the body containing the curve;
- local SC of curve is the system of coordinates in which the curve is defined by an expressions or a set of points.
The local SC can coincide with the main one.
The
button is used for visualization of the curve, Figure 3.87, right. The main SC is drawn
by thick lines, the local one by thin lines, Figure 3.88.
Figure 3.89. Position of local SC relative to main one
Position of the local SC relative to the main one
To set the parameterized position of the local SC relative to the main one, the standard interface is used, Figure 3.89, Sect. 3.6.4.
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Figure 3.90. Setting locking end points
Locking end points
The “Locking end points” group is used for locking or unlocking the curve end points, Figure 3.90. Checked points are locked. Locked points are drawn by thick points, Figure 3.88.
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3.6.7.2. Setting curves by analytic expressions
Figure 3.91. Expressions for a circle
Figure 3.92. Analytical description of a spiral with parameterized number of coils
A big variety of classical plane and spatial curves can be described by analytic dependence
on p parameter, Figure 3.91, Figure 3.92.
The curve is specified by
 interval of parameter p values,
 dependencies of the curve coordinates on p in the local SC of the curve; elements of the list
of variables can be used in the expressions, Sect. 3.5.2.4.8.
Both identifiers and standard functions are allowed in the expressions, Sect. 3.5.2.4.3.
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3.6.7.3. Setting curves by 2D points
This type of curve is used in the case when all points of the spatial curve lie in a plane coinciding with the XY plane of the local SC, Figure 3.93.
Figure 3.93. Curve as a set of points in a plane
Figure 3.94. 2D curve editor
To define the plane curve, click on the
Sect. 3.5.3 for more details.
button and open the curve editor, Figure 3.94. See
Figure 3.95. Spatial positioning of plane curve relative to main SC
Remark 1.
Remark 2.
Coordinates of points can be parameterized.
Shift and rotation of the local SC relative to the main SC allows the spatial positioning of the curve, Figure 3.95.
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3.6.7.4. Setting curves by 3D points. B-spline
Figure 3.96. Set of points for 3D curve
The B-splines of order m=2-10 are used for description of 3D curves by a set of points - vertices. B-splines are power functions of order (m-1). Thus, B-splines of second order are polylines
passing through the given vertices. The B-spline of the forth order is the most frequently used
one; in general this spline has smooth second derivatives.
Editing of list of vertices
The following buttons are used for development of the list of vertices (Figure 3.96):
- add a vertex with zero coordinated to the end of the list;
- copy the current vertex and add it to the end of the list;
- insert a vertex with zero coordinates before the current selected vertex;
- delete the current vertex;
- read a set of points from a text file; the file must contain Cartesian coordinates of vertices in three columns like
1.4733433255E-1 1.3808948848 0.1
1.5971679659E-1 1.4227401843 0.12
1.7768028748E-1 1.4645854838 0.12
2.5001219032E-1 1.5064307834 0.1
………..
Parameterization of vertices
Coordinates of vertices can be parameterized, i.e. identifiers and standard functions can be
used.
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m=2
m=3
m=4
Figure 3.97. Open B-splines of different order for the same set of points
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Order of B-spline
Order of a B-spline specifies the smoothness of the curve: the higher is the order the smoother is the curve, Figure 3.97. The minimal value m=2 (polyline), the maximal order is m=10 (UM
restriction). Besides, the order cannot exceed the number of vertices in the list. As a rule, if m>2,
the curve does not pass through the vertices exactly. There exists a simple trick how to make the
curve passing exactly through a separate vertex.
The recommended value of the order is m=4.
Figure 3.98. Closed unperiodic B-spline, m=4
Closed unperiodic B-spline
To create a closed unperiodic B-spline, the first and the last vertices in the list must be equal,
Figure 3.98. In the closure point the tangent is not smooth, which corresponds to the derivative
discontinuity.
Figure 3.99. Periodic B-spline, m=4
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Periodic B-spline
To specify a periodic B-spline, check the Periodic key. As opposed to the closed unperiodic
spline, as a rule the fist and the last vertices are different, Figure 3.99.
k=3
k=2
k=1
Figure 3.100. Curves with different multiplicity k of the second vertex, m=4 (left). List of vertices in which the second vertex has multiplicity 3
Multiplicity of vertex
Multiple vertices, i.e. the successive vertices with equal coordinates, lead to decrees of the
curve smoothness in this point. If the multiplicity of vertex is equal to m-1, the curve exactly
pass through this point with a jump of the tangent.
Figure 3.101. Approximation of curve consisting of three sections
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Approximation of curve with B-spline
To apply the B-spline for a sufficiently good approximation of a curve, it is required a big
enough number of vertices. For instance, approximation of the curve in Figure 3.101 having
three sections requires a big number of vertices on the arc part.
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3.6.8. Input of Graphical Objects
For description of graphical objects (GO), a built-in graphical editor is used. It is accessible
with the inspector tab Images. Notice that it is recommended to describe the rest of object elements after the complete description of graphical images. In this case the visual verification of
input data is possible, and it allows avoiding a lot of input errors.
Remark.
Recently the most part of images of bodies are created by the user in one of the
CAD programs, Sect. 3.10. Nevertheless, images of force elements like strings
and dampers is recommended to develop by the standard UM tools. Besides,
sometimes full parameterization of UM images is important by the development
of models.
3.6.8.1. Lists of Graphical Objects and Graphical Elements
To visualize any UM element (body, joint, force element and others; bodies will only be
mentioned below), it is necessary to assign a graphical object to it. GO is a set of graphical elements (GEs), which should be created using the built-in graphical editor. The same GO may belong to different (geometrically identical) bodies. For example, for description of GO of a bogie
having four similar wheels (even if they have different masses), it is enough to create two GOs: a
body and a wheel. The same wheel GO is assigned to each of the wheels.
It is desirable to create a full set of GOs before input of data for bodies, joints etc. In this case
the visual verification of the object development process is possible.
After assigning a GO to an object element, UM superposes the SC of GO with the element
SC in a certain rule, but it should be remembered, that the shape and sizes of GO are not connected at all with inertia parameters of body, stiffness of spring and other parameters of the object elements, which should be described separately. Exclusion presents the case when the option
for automatic calculation of body inertia parameters is turned on.
To add or modify graphical objects or elements (GOs or GEs) use the Images tab of the object inspector, Figure 3.102.
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Figure 3.102. Graphical object in the data inspector
Each GO is a set (list) of graphical elements (GE). Lower buttons
are intended
for:
 adding a new GE;
 copying (duplicating) the current GE;
 deleting the current GE.
To set (change) the type of the current GE a drop-down box is used, which contains names of
the standard GEs:
 Polyhedron, Sect. 3.6.8.2.1;
 Ellipse, Sect. 3.6.8.2.2;
 Box, Sect. 3.6.8.2.3;
 Spiral, Sect. 3.6.8.2.4;
 Ellipsoid, Sect. 3.6.8.2.5;
 Cone, Sect. 3.6.8.2.6;
 Parametrical GE, Sect. 3.6.8.2.7;
 Profiled GE, Sect. 3.6.8.2.8;
 Z-surface, Sect. 3.6.8.2.9;
 Spring, Sect. 3.6.8.2.10;
 Link, Sect. 3.6.8.2.11;
 Plate, Sect. 3.6.8.2.12;
 Reference to GO, Sect. 3.6.8.2.13.
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While describing almost all parameters of GEs, identifiers and symbolic expressions may be
used.
Remark.
Changing a type deletes previously entered data for the current GE.
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3.6.8.2. Input of graphical elements (GE)




Each GE has four groups of parameters located in the different tabs (Figure 3.102):
Parameters – a tab with GE parameters depending on its type;
Colors – a tab with GE color information;
Position – a tab with parameters describing position and orientation of the current GE in the
SC of the current GO;
Material – parameters defining inertia properties of the GE material (such as density). They
are used for automatic calculation of inertia parameters of bodies.
3.6.8.2.1. Polyhedron
A polyhedron is used when a GE of irregular shape is needed. An UM polyhedron is a set of
3D vertices forming one or more polygons. The polygons may be drawn both in wired and surface modes.
To describe a polyhedron, the following parameters should be set (Figure 3.103).
 Coordinates of vertices. If only vertices are given, the result is a single polyline connecting
the vertices. If several polygons are needed, the lower part of the form shown in
(Figure 3.103) is to be filled.
 For each of the polygons, vertex indices separated by commas should be pointed; filled polygons should be marked with .
Figure 3.103. Polyhedron
Example. Four vertices might set a tetrahedron
(0 0,0), (1,0,0), (0,1,0), (0,0,1)
by four polygons
(1,2,4), (4,2,3), (1,4,3), (1,3,2).
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3.6.8.2.2. Ellipse
Figure 3.104. Example of ellipse




Parameters of an ellipse (Figure 3.102):
a, b are the semi-axes;
boundary values of an angles for a elliptic sector. The default values (0,0) correspond to a
full ellipse;
discretization is the number of points approximating the ellipse;
fill option determines the element either as a surface or a line.
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3.6.8.2.3. Box
All ribs of a box are parallel to the axes of the GE-fixed SC. The box parameters are
Figure 3.105. Example of box
Length, width, height A, B, C as constant symbolic expressions, Figure 3.105.
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3.6.8.2.4. Spiral
This GE is used customarily as to draw elastic linear of bipolar force elements. The spiral parameters are (Figure 3.106):
 coil radius r (a constant symbolic expression);
 spring height H (a constant symbolic expression);
 the number of coils;
 coil discretization (number of points per coil).
Figure 3.106. Parameters of a spiral
The axis of the spiral coincides with the z-axis of the GE-fixed SC.
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3.6.8.2.5. Ellipsoid
Figure 3.107. Parameters of an ellipsoid
This GE creates an ellipsoid, in particularly a sphere (Figure 3.107).


The parameters of an ellipsoid are:
a, b, c are the semi-axes;
Slices, Stacks are the numbers characterizing the surface discretization.
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3.6.8.2.6. Cone
The cone parameters are shown in Figure 3.108.
Figure 3.108. Cone
The GE allows getting such images as cylinder, cone and truncated cone, as well as a part of
these surfaces.
For description of the conic surface the user should set the following parameters:
 R1, R2 are the radii of the upper and bottom circle-bases;
 h is the height of cone;
 Angles are the boundary values (in degrees) that form a plate angle at the Z-axis delimiting
the conic surface. The angles are counted from the X-axis counterclockwise. If both angles
are zeros, the full cone (cylinder) is generated;
 Number of points on the circle bases and the generating line, which define a discretization
of the conic surface;
 Closing is the switch with three positions (None), Sector, Segment. It defines how the conical surface should be closed.
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3.6.8.2.7. Parametrical GE
The GE provides the wide possibilities to describe the complex surface by analytic expressions (Figure 3.109). Description of both 3D curves and surfaces is allowed. The user should describe them as arbitrary functions of a single (p1 or p2) or the two parameters (p1 and p2).
Figure 3.109. Parametrical GE



The parameters of the parametrical GE are
the drop-down menu Standard contains a set of parametrical elements:
Plane
Ellipsoid
Ring
Torus
Cone
Paraboloid
Spring
Horn
Molecule (Figure 3.109)
Smooth cube
Gear
Elliptic gear
the Equation group contains analytical expressions describing the dependence of the Cartesian coordinates X, Y and Z on a parameter p1 or p2 for a 3D curve, or p1 and p2 for a 3D
surface;
the Parameter limits group sets the minimal and the maximal values of the parameters, and
the number of points inside the interval to approximate the surface; for example, the values
p1 from –1.4 to +1.2, p2 from –0.2 to 4.8 modify the surface above as shown in Figure 3.110.
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Figure 3.110. Influence of the parameters p1, p2 on the GE shape

Closing is a possibility to complete the surface to the closed one by adding lids; since the
parameters p1 and p2 are equivalent, so a lid can be treated either as the p1=const or as the
p2=const surfaces (Figure 3.111); for this purpose the corresponding switch is intended
(Figure 3.109).
Figure 3.111. Different ways of making the parametric GE closed
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3.6.8.2.8. Profiled GE
This GE has many possibilities. It defines a surface formed by moving a certain profile curve
along another axis curve. There is a number of ways to build the curves.
Figure 3.112. Profiled GE: a cylinder




An example of the profiled GE is shown in Figure 3.112.
Parameters of the profile are:
Type of section – possible values are:
 Circle: semi-axes are Scale X, Scale Y;
 Curve 2D:
a section given by a number of points, holes are allowed, too;
 Spline 3D:
a set of consecutive sections given by points;
 Expression: a section given by analytical formulas.
Scale X, Scale Y – scales in X and Y axes;
Number of points to approximate the section;
Close – a switch for automatic adding lids to make the surface closed.
Parameters of the axis curve are:
 Type of curve – possible values are:
 Straight line;
 Circle;
 Curve: given by points;
 Expression: given by analytical formulas.
 Length – the length of the axial line (in case of straight axis curve);
 Number of points to approximate the axial curve.
Using various combinations «type of profile curve – type of axis curve», it is possible to get
different shapes of GE.
Examples of profiled elements
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After choosing the profile type Curve 2D or Curve 3D, a new input parameter Description
appears (Figure 3.113)
Figure 3.113. Profiled GE: a Curve 2D section
Clicking mouse button on
, the user can open a window of the curve editor
(see Sect. 3.6.8.6) and input the section.
If several curves are presented with the Curve 2D type then the profile section will be multiple connected (Figure 3.113).
In case of the Curve 3D section type, several curves are treated as a set of consecutive sections along the axis curve (Figure 3.114).
Figure 3.114. Profiled GE: a Curve 3D section
After choosing the Expression type of profile section, a new parameter group appears
(Figure 3.115):
 x(p), y(p) are the parametric equations of the 2D profile curve depending on p;
 Pmin, Pmax are the p interval boundaries.
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Figure 3.115. Profiled GE: section given by formulas
Analogously, the axis curve can be described by points (Figure 3.116).
Figure 3.116. Profiled GE: a 2D axis curve given by points
Finally consider the image of a wheelset, which is created with the profiled elements, Figure 3.117.
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Figure 3.117. Image of a railway wheelset
Remark.
Computation of inertia parameters is not supported for a profiled element.
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3.6.8.2.9. Z-surface
A GE of this kind is intended for programming graphical image of an arbitrary surface in the
control file. The surface should be described as
z  f ( x, y ) ,
where x and y coordinates correspond to parameters p1, p2.
Figure 3.118. Z-surface parameters


The GE description includes
name of function;
parameter ranges – limits of changing both p1 and p2 parameters and numbers of pointes
to approximate the surface.
When generating equations of motion, a template for zSurface function is included in the
control file (for example, as Pascal code):
function ZGraphicElementFunctions (
_index, _isubs : integer;
_p1, _p2 : real_ ) : real_;
begin
_ := _PzAll[SubIndx[_isubs]];
case _index of
0 : begin
{ Function zSurface }
Result := 0;
end;
end;
end;
For each function of type Z-surface introduced for representation of graphical images, an operator Result := 0 is inserted, and the user should replace it with a proper calculation.
GE of type Z-surface is used to represent images with the help of complex implicit functional
expressions, including time-dependent ones. For example, the Z-surface was used to get a traveling wave (Figure 3.119).
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Figure 3.119. Z-surface
More detailed information concerning this GE is discussed in the manual for programming in
UM environment.
Remark 1.
Remark 2.
Since the real description of the GE is located in the control file and is accessible
in the UM Simulation program only, so in the input program the element is
showed as a rectangle of sizes defined by change limits of parameters p1, p2.
Use of this element requires generation of equations of motion in the symbolic
form, Sect. 3.9.
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3.6.8.2.10. Spring
Figure 3.120. Example of a spring
A Spring GE (Figure 3.120) has been developed for images of cylindrical springs, Figure 3.121. The list of parameters of the element is similar to that for the Spiral element,
Sect. 3.6.8.2.4. Additional parameters are
 type of spring Left/Right,
 bar diameter,
 bar discretization.
Figure 3.121. Use of GE ‘Spring’ in the model of a locomotive bogie
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3.6.8.2.11. Link
Figure 3.122. Parameters of ‘Link’ element
The Link element is a rectangular plate with rounded corners, Figure 3.122. The position and
sizes of the plate are the following:
 coordinates of centers of round parts in the Points group;
 radius of the rounding which is the half of the plate width;
 depth of the plate;
 the Additional rotation key rotates the plate on 90 degrees about its longitudinal axis.
3.6.8.2.12. Plate
Figure 3.123. Plate parameters
The Plate element is a triangle plate with rounded corners, Figure 3.123. The position and
sizes of the plate are the following:
 coordinates of centers of round parts in the Points group;
 radius of rounding;
 depth of the plate;
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3.6.8.2.13. GO as a graphic element
This type of graphical element is a reference to a previously crated GO in the list, or GE-GO.
The element is recommended in the following cases:
 an image contains several equal parts,
 by merging several GO into one image,
 by import data from CAD programs; in particular, by merging parts into one body,
Sect. 3.10.3.
Figure 3.124. Example of a graphic element as a reference to GO
The reference to a GO is selected from the drop-down list, Figure 3.124.
The
button is used to access the referenced GO.
The referenced GO can be directly included in the current GO by the
button.
This type of element allows the user to create a many time repeating group of graphic elements as a separate GO and insert it several times into another GO. After that, the correction of
included GO leads to modification of all the GE-GO.
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Figure 3.125. Graphic image of a fright couch body
For example, consider an image of a fright couch body. It includes a lot of repeating parts
(stiffening ribs) one of which is selected in the picture (Figure 3.125). It should be created a GO
corresponding to a separate rib and then this image is dozens of times included in the image of
the body as GE-GO and positioned by a proper way. If the image of the rib must be modified
(e.g. its height must be reduced), the only GO of the rib should be corrected, and all the ribs included in the image of the coach body are changed automatically.
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3.6.8.2.14. Graphic element ASC imported from CAD program
Figure 3.126. Example of an ASC element
Graphic elements of the ASC type correspond to images imported from CAD programs,
Sect. 3.10. The element contains a set of vertices and a set of triangles specified by indices of
vertices, Figure 3.126. Neither vertex coordinates nor triangles can be modified.

The user can change the following data and parameters.
Smoothing angle. The angle is used for an automatic smoothing of the surface; a common
side of two neighbor triangles is considered as an edge (and not smoothed!) if the angle between the triangles is greater than the given value; in particular, for zero value of the
smoothing angle, no smoothing take place, Figure 3.127.
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Chapter 3. Data input program
25
45
Figure 3.127. Smoothing of surface for different values of angle parameter


The Vertices visible key makes vertices visible/invisible in the animation window. If vertices are visible, a click by the mouse on the vertex image allows the user to find the vertex
coordinates in the list.
The Automatic detection of edges key calls a procedure for evaluation of edges, if the edges are not imported from CAD program, Figure 3.128.
Figure 3.128. Edges before and after automatic computation
Remark.
If a model includes a big number of ASC elements, edges for all of them can be
detected by one operation. To do it, open the Object tab in the inspector and
check the key Compute edges for ASC, Figure 3.129.
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Figure 3.129. Key for automatic computation of edges for all of the ASC elements
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3.6.8.3. GE colors
Colors of a GE are set by parameters on the Color tab, Figure 3.130.
Figure 3.130. Colors of GE




There are several kinds of color parameters:
Diffuse (color of material);
Specular (color of the reflected light); black color means no reflection;
Emissive (the object shines with this color); it is off if the color is black;
Ambient (usually not used).
To choose each of the colors, click mouse button on the corresponding color rectangle.
Use the
button to select one of the standard color sets.
The parameter Shininess defines size of the reflected light’s spot.
Check the Wired option to set the element into the wire mode; simultaneously the Width of
curves parameter set the line width.
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3.6.8.4. Position and Orientation of GE
Figure 3.131. Position and orientation of GE
Each GE is described in its own system of coordinates SC GE, which can be positioned in
SC GO in an arbitrary way, see Sect. 3.6.4.
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3.6.8.5. Inertia parameters of GE
Figure 3.132. Inertia parameters of GE material
Inertia parameters of bodies (mass, tensor of inertia, coordinates of center of mass) can be
computed automatically according to the body image. A necessary condition for that is filling the
material properties for graphic elements (at least for one of them). On the Material tab
(Figure 3.132) set
 Density
 Type of graphic element (solid, hollow) or frame (for wire element, Sect.3.6.8.3)
 A thickness and a section square should be set for a hollow and a wire GE
Warning. Automatic computing of inertia parameters may lead to wrong results if separate
graphic elements interSect. The intersected volumes are taken into account several times. For
example, the mass of the body is computed according to the formula
m   mi
m
where i is the mass of a separate GE calculated independently on possible intersections.
The computation of inertia parameters is not supported for a profiled element,
Sect. 3.6.8.2.8.
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3.6.8.6. Curve editor
The window of the curve editor is shown in Figure 3.133. See Sect. 3.5.4 for additional information about this tool.
1
9
1
5
2
1
1
8
4
2
1
6
1
2
2
6
11
1
7
10
4
3
Figure 3.133. Curve editor







Main elements of the editor are marked in Figure 3.133 by indices:
graphical primitives:
1 – straight lines;
2 – cubic splines;
3 – B-splines (special kind of splines);
4 – circle (arc);
points (vertices):
5 – a point of smooth conjugation of primitives;
6 – a point of non-smooth (sharp) conjugation of primitives;
continuous curves (continuums):
1-5-2-1-6-1-1-2-1-6-1-4-2-2, and also 3 – non-closed curves;
4, 7 – closed curves;
other controls and possibilities of the editor:
8 – drop-down list of types of primitives;
9 – panel of control buttons;
10 – list of curves;
11 – open the list of point coordinates of the current (selected) curve.
To add points (vertices), double click by the left mouse button in the desired position.
To copy a curve:
select it using mouse pointer;
put it to the Windows clipboard;
insert from the clipboard.
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Exchange with the clipboard is performed using a text format. So, the user can type coordinates of vertices as two columns of numbers in any text editor, and insert them into the curve
editor.
Pop-up menus are used for various actions with primitives and points of curves. It appears after clicking the right mouse button over the corresponding element.
For example, clicking over the free field of the curve editor results in appearing a pop-up
menu shown in Figure 3.134.
Figure 3.134. Curve editor main pop-up menu


The menu has two items:
Start new curve – the next point being input will be the start point of the new curve (continuum);
Select all – is used to select all curves in the editor.
Clicking right mouse button over any vertex results in appearing a pop-up menu for a point
(Figure 3.135).
Figure 3.135. Pop-up menu for a point
Actions allowed for a selected point are:
 Properties... – opens a point property dialog box intended for changing the point coordinates;
 Delete – removes the selected point;
 Smooth – turns on/off the smooth conjugation of primitives.
A pop-up menu for a primitive appears after clicking any primitive (line, spline or circle); see
Figure 3.136.
Figure 3.136. Pop-up menu for primitive

Actions allowed for a primitive are:
Convert into – changes the type of the selected primitive;
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Insert point – a new point will have the coordinates defined by the current position of the
mouse pointer (double clicking the left mouse button has the same effect);
Delete – removes the selected primitive;
Properties... – calls a primitive property dialog box;
Select whole curve – selects the curve (continuum) containing the selected primitive;
Closed – a tag for closing the curve containing the selected primitive;
Reverse order – for inverting the ordering of points;
Rotate 90 – turns the current continuum through 90 degrees counterclockwise.
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3.6.9. Describing rigid bodies
The Bodies item of the object element tree (Figure 3.137 left, Sect. 3.5.1.1) is used to access
the tool of creation and modification of the list of bodies and their parameters. Alternative ways
are the Ctrl+Alt+B hot key or clicking by the mouse on the corresponding body image in the
whole object mode of the animation window (Sect.3.5.1.2.2). The right picture in Figure 3.137
shows the inspector with parameters of a body.
Figure 3.137. Bodies item of the object element tree and body parameters
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3.6.9.1. Image and visualization of a body. Body-fixed SC
3.6.9.1.1. Assignment of an image to body
The Image pull-down list contains the list of available graphical objects, Sect.3.6.8. Click the
button to access the assigned GO parameters or to create a new GO, which will be assigned to
the body.
The SC of the assigned GO coincides with the body-fixed SC. That is why the image moves
when the body changes its position and orientation.
3.6.9.1.2. Modes of animation window and body image
Use the single element mode of the animation window (Sect.3.5.1.2.2) to see the body-fixed
SC and the body image.
a)
b)
c)
d)
Figure 3.138. Visualization of an active body in different modes of the animation window
Figure 3.138 shows visualization of a motor body in different modes of the animation window:
1.
Full object mode. The button
must be in the ‘down’ state. The active body is drawn as
selected, axes of the SC0 are drown.
2.
Single element mode. The button
must be in the ‘up’ state. The window contains the
body image in the body-fixed SC which axes are drawn. Modes of drawing
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
shaded mode, button

wired mode, button

contour mode, button

shaded mode with edges, button
Chapter 3. Data input program
,
,
,
.
Important remark. A body is drawn in the full object mode of the animation window, if there
exists a path from the body to the Base0 through the joints (Chapter 2,
Sect. Compendency of systems and the definition of a joint). For example, if
body2 is connected to body1 and body1 is connected to Base0 by means of two
rotational joints, both body1 and body2 are visible in the full object mode. If the
joint between body1 and Base0 is removed, both bodies disappear. If the joint between body2 and body1 is removed, body1 disappears.
3.6.9.1.3. Modes of body image
A body can be made temporarily wires or invisible independently on the state of the animation window.
3.6.9.1.3.1. Invisibility of body
In particular, the invisibility mode of a body is used by merging a number of parts into a
body for models imported from CAD, see Chapter 9. The mode can be set by the following
ways:
 the Visible key in the inspector, Figure 3.137; the same key make the body visible;
 the Make invisible “name of body” command of the pop-up menu of the animation window, Figure 3.139; to call the menu, move the mouse cursor to the body image and click the
right mouse button; this method is available only if the button for visual operations
the ‘down’ state;
is in
Figure 3.139. Fragment of pop-up menu of animation window

the Body “Name of body” visible command of the pop-up menu of the tree of elements,
Figure 3.140; to call the menu, move the mouse cursor to the name of the body in the tree
and click the right mouse button; the same command is used to make the body visible;
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Figure 3.140. Pop-up menu of tree of elements
The invisible body is marked in the element tree by the icon
, Figure 3.141.
Figure 3.141. Icon of invisible body
Remark.
The invisibility mode does not affect the image of the body in the simulation
module, where an alternative method for changing visibility is used.
3.6.9.1.3.2. Wired body mode

The wired mode can be set by the following ways:
the Body wired “name of body” command of the pop-up menu of the animation window,
Figure 3.139; to call the menu, move the mouse cursor to the body image and click the right

mouse button; this method is available only if the button for visual operations
is in the
‘down’ state;
the Body wired command of the pop-up menu of the tree of elements, Figure 3.140; to call
the menu, move the mouse cursor to the name of the body in the tree and click the right
mouse button; the same command is used to cancel the mode;
The invisible body is marked in the element tree by the icon
, Figure 3.142.
Figure 3.142. Icon of wired body in element tree
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3.6.9.1.4. Reassignment of body image in simulation program



The body image can be reassigned in the simulation module, Figure 3.143:
move cursor to the body image,
open the pop-up menu by the right mouse button,
select the Assign GO [Name of body] | [Name of GO] command, Figure 3.144.
Figure 3.143. Reassignment of graphic object to the body ‘Car body’
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Figure 3.144. Model of a freight car with reassigned imaged of the car body
Reassignment of the images is stored in the configuration file of the model *.icf.
3.6.9.2. Inertia parameters




Inertia parameters of a body are:
mass;
symmetric inertia tensor;
coordinates of center of mass in the body-fixed SC;
symmetric added mass matrix.
The icon
marks the position of the center of mass in the animation window.
Important remark and warning. Moments of inertia and elements of the added mass matrix
should be calculated in SC, which origin coincides with the center of mass and axes are parallel
to those of the body-fixed SC.
There exist two modes for setting the inertia parameters except the added masses. Use the
Automatic calculation key to select the necessary one, Figure 3.137.
User’s defined inertia parameters
All parameter edit boxes are enabled in this mode. The parameters might be constant symbolic expressions (Sect. 3.5.2.4.5).
Automatic calculation of inertia parameters
The parameters are calculated automatically according to the body image (Sect. 3.6.8.5). Parameter edit boxes are not available for the user.
Note.
In this mode inertia parameters are calculated automatically for nearly all graphical objects; however, the problems may occur when using polyhedrons
(Sect. 3.6.8.2.1). For correct calculation, it is required that, when defining faces
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of the polyhedrons, the order of vertices were set counterclockwise if seen from
outer side of the object. Otherwise, the automatically computed inertia parameters
might be incorrect. For example, in definition of a user-defined parallelepiped
shown in Figure 3.145 there is wrong set of vertices for the second (vertices
5,6,2,1) and the third (vertices 6,7,3,2) face since this order of vertices corresponds to clockwise order. As a consequence, the center of mass is calculated incorrectly, see the figure. If the user changes the order of vertices to 1,2,6,5 and
2,3,7,6 respectively, the center of mass (and other inertia parameters) are computed correctly, see Figure 3.146.
Figure 3.145. Incorrect enumeration of vertices of a polyhedron when automatic computing inertia parameters
Figure 3.146. Сorrect enumeration of vertices of a polyhedron when automatic computing inertia
parameters
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Added mass matrix
Figure 3.147. Window for elements of added mass matrix
The added mass matrix mainly used for simulation of bodies moving in a fluid 1 as well as in
the case of railway wheelsets. Let M be the 6x6 inertia matrix of a rigid body specified in the
body-fixed SC
0
 mI
M   3

J  ,
 0
where m is the mass of the body; J is the matrix of the inertia tensor relative to the center of
I
mass, 3 is the 3x3 identity matrix. If we denote A the 6x6 added mass matrix, which element
are set in Figure 3.147, the equations of motion of the body look like
( M  A)W  k  G,
a
 0 
F
W   , k   ~ , G   ,

 J
T 
Here a, ,  are the acceleration of the body center of mass, the angular acceleration and the
angular velocity of the body; F,T are the principal vector and torque of the applied and reaction
forces reduced to the center of mass. All vectors in this equation are resolved in the body-fixed
SC.
Remarks.
 Automatic calculation of inertia parameters is enabled after assigning a GO to the body. The
corresponding GO must include at least one GE with the specified material which density is
not zero.
 Inertia parameters are recalculated every time when the GO is modified, in particular when
identifiers parameterizing the GO are changed.
1
Newman, John Nicholas (1977). Marine hydrodynamics. Cambridge, Massachusetts: MIT Press.
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3.6.9.3. Internal (hidden) body joint
Position and motion of a body relative to SC0 can be defined by an internal or hidden joint.
Type of joint is “6 d.o.f”, Sect. 3.6.11.6. The following tools are available for creating a body
with an internal joint


the
button in the inspector, Figure 3.137,
the Add body with internal joint command of the popup menu of the element tree, Figure 3.148.
Figure 3.148. Adding a body with internal joint by popup menu command in element tree
Figure 3.149. Icon of body with internal joint having six (left) and zero (right) degrees of freedom
The joint is referred as an internal one because it is not visually presented in the list of joints
of the model. Consider some features of the internal joint.
1.
An internal joint can have either six or zero degrees of freedom, Figure 3.149. In the first
case, the joint specifies the position of the free body relative to the SC0. It the second case,
the joint fixes the body to the SC0 and the body-fixed SC coincides with SC0. The number
of degrees of freedom is set by the user, Figure 3.150.
Figure 3.150. Number of degrees of freedom of an internal joint
Example of using internal joint with six degrees of freedom: fictitious body, Sect. 3.6.3.3.3.
Example of using internal joint with zero degrees of freedom: body Ground, Sect. 3.6.9.7.
2.
In case of an internal joint with six d.o.f., three Cartesian coordinates set location of the
origin of the body-fixed SC relative to SC0, and three orientation angles specify the orienta-
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tion of the body-fixed SC. The sequence of the rotation angles is (1,2,3), Sect. 3.6.11.6. SC
of the body coincides with SC0 for zero values of coordinates.
3.
A large weight is assigned to the internal joint, Sect. 3.6.11.2. If the user connects this body
with SC0 by a usual joint either directly or through a chain of bodies, the internal joint is cut
and obtains the status of the deleted joint. It is important to know that cut joints with six
degrees of freedom do not affect the motion process and ignored, Sect. 3.6.11.4.2. If the
joint connecting the body with the SC0 is removed, the internal joint is restored.
4.
Values of coordinates of internal joint with six d.o.f. can be changed on the Position tab of
the inspector, Sect. 3.6.9.4, as well as on the Coordinates tab, Sect. 3.5.2.3.4.
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3.6.9.4. Position tab
Figure 3.151. Position of body relative to SC0
The Position tab reflects the current position of the body-fixed SC relative to the SC0, Figure 3.151.
Values of coordinates can be changed on this tab if the body has a non-deleted internal joint
with six d.o.f., Sect. 3.6.9.3. Otherwise, the coordinates are given for information only and cannot be changed here.
Remark.
To see the actual position of the body relative to SC0, set the full object mode in
the animation window by the
button on the tool panel, Sect. 3.5.1.2.2.
3.6.9.5. Rapid access to elements connected with body
Use the
button (Go to element, Figure 3.152) for rapid access to elements connected with
the current body:
 body image,
 joints,
 force elements,
 contact manifold.
Figure 3.152. List of elements connected with the body
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3.6.9.6. Connection points









Connection points are assigned to the body. They are used by
operations with visual components;
describing joints and force elements (visual assignment of bodies, joint and attachments
points);
assignment of bodies as well as the corresponding joint and attachment points to external
joint and force elements (for subsystem technique only).
There exist three types of connection points:
general
oriented (local body-fixed SC)
vectors
The following parameters should be set for each of the points
coordinates in the body-fixed SC (coordinates are parameterized);
comments simplifying operations with points (auxiliary parameter);
orientation of point-fixed SC relative to the body-fixed SC (for oriented point); the orientation is set by three rotations.
An icon marks a connection point in the animation window (Figure 3.153). A point-fixed
SC are additionally drawn for oriented points, and a red line section is drawn for a vector along
its direction.
Figure 3.153. Frame with general and oriented connection points
Note.
Connection points are used to assign their positions and/or orientation to object
elements (joints and forces). At the same time the connection between the element and the points is not kept. This means that if the user changes the point parameters after its usage for description of an element, the corresponding changes
are not transferred to the element automatically.
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3.6.9.6.1. Adding general connection points
Tools for list
modification
Tools for visual
creation of points
List of points
Figure 3.154. List of general connection points
The Points tab is used to create or modify the list of points, Figure 3.154.
To add a point, the user should set its coordinates in the body-fixed SC. Here are instructions
how to do this.
1. Use the
(add) or the
(copy) button. Set point coordinates as constant symbolic expressions.
2. Click the
button, select by the mouse a point on the body image, and click the mouse
button again. The selected point is added automatically.
Second click
Result
First click
Selection of
image vertex
Figure 3.155. Adding a point as a middle point of a section
3.
The
button allows the user to get a point as a middle point of a section selected by the
mouse, Figure 3.155.
4.
The button
adds a point which is the center of a circle passing through three points selected by the mouse.
Use vertices on the body image for exact positioning of points. Near the vertex the mouse
cursor is changed to
button.
. After visual adding, the point can be corrected or removed by the
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3.6.9.6.2. Adding oriented connection points
Use the Oriented points tab to add oriented connection points (a local system of coordinates,
LSC), Figure 3.156. Its description includes coordinates of the points and the orientation of axes
of the LSC in the body-fixed SC. The orientation is set as a sequence of three successive elementary rotations.
Figure 3.156. List of oriented points
Here five methods for adding oriented points (LSC) are described.
1.
Use the
(add) or the
(copy) button. Set point coordinates as constant symbolic expressions. Set rotation axes and angles in degrees to define the orientation.
Figure 3.157. Adding a LSC by a normal and a point
2.
Visual adding by a normal and a point.
 Click the
button.
 Select a vector or a point on a plane for the origin and the Z-axis of the LSC.
 Select a point in the XZ-plane.
3. Visual adding by an opposite normal and a point.
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Click the
button.
Select a vector or a point on a plane for the origin and the Z-axis of the LSC. The Z-axis
is directed opposite to the vector or inside the plane surface.
Select a point on the XZ-plane.
Visual adding a LSC by tree and by four points
4.
Visual adding by three points.




5.
Click the
button.
Select a point for the origin of the LSC.
Select a point on the X-axis.
Select a point in the XY-plane.
Visual adding by four points.


Click the
button.
Select two points. The middle point of the section is the origin of the LSC, and the vector
r12 connecting the points set the X-axis.

r r
Select the 3rd and the 4th points. The cross product 12 34 sets the Z-axis.
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3.6.9.6.3. Adding vectors
Use the Vectors tab to add a vector. Its description includes coordinates of the points and
components defining the direction of the unit vector in the body-fixed SC. The vectors are used
for visual correction and adding joints and some special force elements.
Figure 3.158. List of vectors
Here five methods for adding vectors are described.
1.
2.
Use the
(add) or the
(copy) button. Set point coordinates as constant symbolic expressions. Set numeric values for the vector components.
Visual adding by a normal and a point.
 Click the button.
 Select a point on a plane for the vector, which is the external normal to the plane.
3. Visual adding by two points.
 Click the button.
 Select a point for the vector point.
 Select the second point for the vector direction.
4. Visual adding by three points.


5.
Click the
button.
Repeat actions for setting the LSC by three points from the previous section. The vector
corresponds to the Z-axis.
Visual adding by four points.


6.
Click the
button.
Repeat actions for setting the LSC by four points from the previous section. The vector
corresponds to the Z-axis.
Visual adding as a normal to the center of a circle passing through 3 points.


Click the
button.
Select three points lying on a circle. The resulting vector begins at the circle center. The
direction of the vector is perpendicular to the circle plane according to the right-hand
screw rule according to sequence of selected points.
3.6.9.7. Body «Ground»
Ground is a body, which could be automatically added to the model by its creating, if the
corresponding option is checked, Sect. 3.3.1.
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The ground body has zero inertia parameters. It is rigidly connected by an internal joint to
SC0, i.e. the internal joint has zero degrees of freedom, Sect. 3.6.9.3. Body-fixed SC coincides
with SC0. In fact, according to the listed properties of the Ground, this body is equivalent to the
SC0, and all bodies connected to the Ground by joints and force elements are connected to SC0.
As opposed to SC0, connection points can be assigned to the Ground (Sect. 3.6.9.6) and used
by visual assignment of the points to force elements and joints.
Another reason for introduction of the Ground consists in the use of this body by conversion
MSC.ADAMS models, Sect. 3.11.
Figure 3.159. Parameters of body «Ground»
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3.6.9.8. 3D Contact
There is a possibility to assign a contact manifold described as a graphical object
(see Sect. 3.6.8) to a rigid body. All bodies that have such a contact manifold will interact between each other during simulation dynamics of a mechanical system in UM Simulation. Parameters of a contact interaction as well as turning on/off contact between pairs of bodies are
available in UM Simulation.
3D Contact supports parameterization of graphical objects that are used as contact manifolds.
Firstly parameterized graphical objects for contact manifolds you can consider various configuration of contacting bodies in quite wide range simply changing corresponding parameters without remaking the graphical object itself. Parameterization of graphical object may be effectively
used, for example, for searching the optimal shape of the friction wedge for so-called three-piece
bogie for freight cars, Figure 3.160 below.
a) Graphical object (GO)
b) Contact manifold (CM)
c) GO and CM
Figure 3.160. Graphical object and contact manifold for a body of wheeled robot
A graphical object that is assigned as a contact manifold for a body may differ from a graphical for the body. It is absolutely not necessary that it should be the same graphical objects. It is
recommended to use simplified contact manifolds for decreasing the CPU efforts for simulation.
The contact manifold for the rigid body is selected from prepared in advance graphical objects that are available in the drop down list. Coordinate system of the contact manifold coincides with the coordinate system of the body. In the Single element mode (see Sect. 3.5.1.2.2.
Modes of animation window, page 3-23) the contact manifold is drawn in yellow lines, see Figure 3.161.
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There is no possibility to assign a contact manifold for Base0 body. If it is necessary you
should create an extra rigid body with 0 d.o.f. and assign the contact manifold of Base0 with this
extra body.
Figure 3.161. 3D Contact parameters between pair of bodies
Types of contact manifold
Polyhedron. In general case use Polyhedron type for describing the contact interaction between bodies. Graphical objects that are chosen as contact manifolds should consist of graphical
elements of the following types: Box, Polyhedron and ASC. Graphical elements of Polyhedron
and ASC types should be convex and closed.
Z-surface. This type of contact manifold is used to describe contact between all bodies and
the ground. Restrictions of convexity and closure are not applied for graphical objects for contact
manifold of Z-surface type. Some comments concerning preparing a graphical object for using
as a contact manifold of Z-surface type are given in Sect. 3.6.12.6.8. Points | Sphere | Circle - Z
surface contact, page 3-219.
3D Contact simulation between Polyhedrons and Z-surface is based on using Points –
Z-surface contact force that is described in Sect. 3.6.12.6.8. That is why it is also possible to describe contact interaction between polyhedrons and Z-surface with the help of Points – Z-surface
contact force. The only difference between both variants is that 3D Contact generates all contact
forces of Points – Z-surface type automatically without necessity to create the forces for each
body and the Z-surface manually. At the same time both variants are identical from point of view
of results of simulation of dynamics of the system.
Treating the Points – Z-surface contact forces in 3D Contact does not consider the interaction of edges and Z-surfaces, so contact forces will not appear in the case which is depicted in
the Figure below.
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Polyhedron
Vertex
Z-surface
Note 1.
Note 2.
CPU efforts for simulation of near contact are proportional to square of count of
faces and edges. To accelerate simulation process it is recommended to simplify
contact manifolds 1 as far as possible for solving the particular problem.
3D Contact model as any mathematical model is just an approximation of real
physical processes that take place between two bodies contacting bodies. Certainly the model has confined area of effective applications as well as there are cases
where the model describes real processes incorrectly. 3D Contact model is rather
a fast algorithm that is suitable for simulation of some models based on multibody system dynamics approach but surely is not suitable for detailed analysis of
contact problem (contact stresses, deformations, wear, plastic effects and so on).
Comparison of the contact models.
Universal Mechanism software has to approaches to simulate contact interaction between rigid bodies. The first approach supposes using contact forces of “point-plane” and other types and
the second approach is based on 3D Contact described above.
3D Contact is based on using “point-plane” contact forces and in this sense can be considered
as an algorithm that detecting interpenetration of rigid bodies arranges contact points and identifies nearest faces as contact planes. At the same time calculation of interpenetration of contact
manifolds is rather time-consuming operation that takes quite many CPU efforts. That is why
simulating models with contacts it necessary to understand clearly advantages and disadvantages
of both approaches. Detailed overview of contact forces see in Sect. 3.6.12.6. Input of contact
force elements, page 3-205.
3D Contact often makes simulation of contact interaction more easy-to-use, intuitive and
more suitable for parameterization, as well as widens contact interaction for “edge-edge” penetration case, see Chapter 2, Sect. 3D contact. To simulate “edge-edge” penetration with the help
of contact forces of “point-plane” type it needs to create contact points on each edge with quite
small distance between them that significantly increases CPU efforts that neglect the only benefit
in comparison with 3D Contact.
Please note that 3D Contact widens possibilities of simulation of contact interactions but
needs extra computational efforts. At the same time approach based on using contact forces generally faster but not so universal as 3D Contact one.
Examples.
Please find some examples of using 3D Contact in the following models:
 {UM Data}\SAMPLES\Misc\Clockwork;
 {UM Data}\SAMPLES\Misc\DominoDay;
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{UM Data}\SAMPLES\Misc\Earthquake;
{UM Data}\SAMPLES\Misc\FallingFigures;
{UM Data}\SAMPLES\Rail vehicles\WedgeTest3DContact;
{UM Data}\SAMPLES\Robots\krt_200;
{UM Data}\SAMPLES\Robots\Manipulator.
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3.6.10. Joints and force elements: some features of description
Joint and force elements have some parameters, which entering is quite analogous, e.g. a pair
of bodies, attachment points or images should be assigned for the most of elements of these
types. The standard interface is used for entering these parameters, for instance the corresponding interface for a bipolar force element looks like in Figure 3.162.
Body1
Body2
Autodetection
key
Image
Attachment point
to Body2
Attachment point
to Body1
Element
type
Figure 3.162. Main element of the interface
3.6.10.1. Assignment of bodies
A pair of bodies should be assigned to each joint or force element else the object description
is considered as incomplete. One of the bodies is the first body (Body 1 in Figure 3.162), and
another is the second body (Body 2). Use two drop-down lists to set the bodies (Figure 3.163).
Figure 3.163. Drop-down list of bodies
The lists contain all bodies included in the object as well as the base body (Base0, SC0) and
an external body (the second list only). The Base0 is used for attachment of a body to a fixed
point (to the base). The External body is used to make the element external, Sect. 3.6.3.3.1.
The first and the second bodies must be different.
3.6.10.2. Type of element
A type must be chosen with the help of a drop-down list (Figure 3.162, Figure 3.164).
Changing the type leads to deleting of previous element description.
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Figure 3.164. List of joint types
3.6.10.3. Attachment points
Attachment points have different notations for elements of different types (‘joint points’, ‘attachment point’ etc.). Anyway two points should be assigned for each element. One of the points
belongs to the first body, another point – to the second one. The coordinates of the point should
be entered in SC of the corresponding body as constant symbolic expressions.
Some elements require assignment of local system of coordinates (LSC) instead of points
(bushing, generalized linear element, 6 d.o.f. joint, etc.) or vectors (rotational and translational
joints, gearing, etc.).
3.6.10.4. Visual assignment of bodies and attachment points
Figure 3.165. Joint points
To assign visually a body and the corresponding attachment point, vector or LSC click one of
the
buttons and select a point, an oriented point or a vector, which should be preliminarily described (see Sect. 3.6.9.6. Connection points).
Note 1.
Note 2.
The type of the point should be chosen depending on the element. For example,
description of a generalized linear force element requires both oriented points and
general point. The description of a bipolar force element requires two general
points.
If the element requires coordinates of a point only, all types of connection points
can be used. If the element requires a vector, an oriented point can be used (Zaxis of the LSC is used as the vector).
3.6.10.5. Autodetection
The autodetection mode can be set for the most of the force elements: bipolar force element,
scalar torque, generalized linear force element, bushing, points-plane contact end so on. If the
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autodetection mode is assigned, the coordinates of attachment point or LSC of the second body
are assigned in SC of the first body by zero values of all joint coordinates.
In particular, the autodetection mode is frequently used by external element disrobed in subsystems, Sect. 3.6.3.3.1.
3.6.10.6. Transformation of coordinates
Attachment points of force elements are set in the body-fixed SC, therefore, a tool for transformation of coordinates of points into different SC could be useful. To call the corresponding
tool use the Tools | Transformation of coordinates ore use the hot key Alt+T (Figure 3.166).
Choose two bodies with the help of drop-down lists and set coordinates of a point in SC of
one of the bodies (where the coordinates are known). After that click either the
button (if the
coordinates are known for the first body) or the
button if the coordinates are known for the
second body), and the coordinates are computed is SC of another body. Analogously can be
computed projections of a vector on the axes of different SC.
Figure 3.166. Example of transformation of coordinates
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3.6.11. Input of joints
3.6.11.1. Visualization of joints
In the single element mode of the animation window: a pair of bodies (kinematical pair) connected by the joint is drawn. A GO may be assigned for a rod constraint only.
In the full object mode of the animation window: the bodies of the kinematical pair are drawn
as active. Optionally an icon marks a position of the joint point and visualizes its degrees of
freedom (Sect. 3.5.1.2.1. Visualization of object elements). Click near the active region of the
icon to call the description of the joint in the inspector (Sect. 3.5.1.2.1).
If the joint is cut (except rod, mate and CV joints), the second body is drawn twice in the full
object mode: in the positions determined by adjusted and the cut joints (Sect. 3.6.11.1). It is recommended to change coordinate values in such a way that the both images of the body were
close. The exact values of the coordinates are calculated in the Simulation program.
Note.
By default some information about the joint is hidden. Use the
it visible.
button to make
3.6.11.2. Weight of joint
Figure 3.167. Setting joint’s weight
A weight coefficient can be assigned to each of the joints. This parameter is used when the
object has closed kinematical loops (Chapter 2, Sect. System graph. Closed kinematical loops). If
a large weight (e.g. 1000) is assigned to a joint in a closed loop, it will be cut.
Note.
By default the weight information is hidden. Use the
Figure 3.167.
button to make it visible,
3.6.11.3. Conversion of joint type
Joint’s types
 rotational
 translational
 six degrees of freedom (6 d.o.f.)
can be converted to the generalized joint type.
For example, a 6 d.o.f. joint can be converted to the generalized type to introduce joint forces
for some degrees of freedom. A rotational or a translational joint is recommended to be trans-
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formed to the generalized joint type, e.g. to add degrees of freedom or to parameterize inclination of the joint axis.
To convert the joint type

use the

click the
button to open additional joint information, Figure 3.167.
button to make the conversion.
Example. User’s manual, Chapter 7, Sect. Joint type conversion. Parameterization of axis
inclination.
3.6.11.4. Status of joint
Irrespective of a type, the joint can have a definite status, which must be known to the user
for professional acquisition of the modeling methods:
 joint in tree,
 cut joint,
 removed joint,
 joint-fixation,
 joint with negative direction.
Consider definitions of these notions in more details. It is recommended to become familiar
preliminary with Chapter 2, Sect. Connectivity of systems and definition of a joint, System graph.
Closed kinematical loops.
3.6.11.4.1. Joint in tree and cut joint. Closure of cut joints
A joint is in tree if it is included in the object tree otherwise it is cut. Thereby, the cut joint is
not used for computation of a body positions relative to SC0 with joint coordinates. In the mathematical sense, the cut joint adds a number of constraint equations to the equations of motion.
Coordinates of joints included in the tree build the set of coordinates of the object relative to
which equations of motion are generated, Sect. 3.5.2.3.4.
There exist two types of cut joints.
1. Joints – constraints, which do not have joint coordinates:
 rigid rod, Sect. 3.6.11.9;
 mate, Sect. 3.6.11.10;
 convel joint, Sect. 3.6.11.11.
These joints introduce restrictions on relative motion of a pair of bodies. The joints of this
type are always cut.
2.
Joint with a set of local joint coordinates included in a closed kinematic loop, and cut by the
program after automatic analysis of the object graph:
 rotational;
 translational;
 joint with six degrees of freedom;
 generalized joint;
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 quaternion joint;
 internal body joint, Sect. 3.6.9.3.
The user can have an influence on the selection of cut joint in a closed loop by the joint
weight, Sect. 3.6.11.2.
The following methods are available for verifying the joint status:
 icon of a cut joint in the element tree is stroked, Figure 3.168;
 status ‘cut’ of a joint is presented in the section of additional joint parameters; the section
is available by the
button, Figure 3.169;
 on the Indices tab of the object inspector, Figure 3.170;
 joint coordinates of a cut joint are marked in the list of coordinates in the simulation
module, Figure 3.171.
Figure 3.168. Icon of a cut joint in the element tree
Figure 3.169. Status ‘cut’ of a joint in the section of additional joint parameters
Figure 3.170. Status ‘cut’ of a joint on the Indices tab
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Figure 3.171. Marker for coordinates in a cut joint
Closure of cut joints
Closure of cut joints is the process of solving constraint equations by the program, Figure 3.172. To close the cut joints, the
button on the tool panel of the animation window or the
buttons
on the Coordinates tab of the object inspector are used.
Figure 3.172. Crank-rod mechanism with open and closed cut joint
Remark.
Solving constraint equations is a difficult numeric procedure, which does not always succeed, see Chapter 2, Sect. Theoretical foundations for solving constraint
equations. If the equations are not solved in the input model and user cannot de-
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tect the cause, it is recommended to do it in the simulation module where advanced algorithms are used.
3.6.11.4.2. Removed joint
The removed status is assigned to the cut joint with 6 degrees of freedom, if the joint does
not contain description of joint forces. Such the joint does not restrict the relative motion of connected bodies and does not affect the kinematic and dynamic properties of the model. In fact, the
joint is not deleted from the model but it is ignored by the program in all computations.
A fictitious body gives an example of using such joints, Sect. 3.6.3.3.3.
If the joint is not an internal body joint (Sect. 3.6.9.3), its status ‘removed’ can be verified by
the following ways:
 icon of the deleted joint in the element tree is crossed, Figure 3.173;
 status ‘removed’ is shown in the section of additional joint parameters; the section is available by the
button, Figure 3.174;
 on the Indices tab of the object inspector, Figure 3.175;
 coordinates of the deleted joint are not included in the list of model coordinates.
Figure 3.173. Icon for removed joint in the tree of elements
Figure 3.174. Status ‘removed’ in the section of additional joint parameters
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Figure 3.175. Status ‘removed’ the in Indices tab of the object inspector
3.6.11.4.3. Fixation joint


Fixation joint is the joint with zero degrees of freedom of the following types:
generalized joint, see Sect. 3.6.3.3.3 as an example;
6 d.o.f. joint, see Sect. 3.6.9.7, 3.6.9.3 as an example.
Figure 3.176. Icon of a fixation joint in the element tree
The joint is used to connect rigidly a pair of bodies.
3.6.11.4.4. Joint with negative direction
The notion ‘joint with negative direction’ is related to the evaluation of a body position relative to SC0 by a chain of joints.
After automatic cutting closed kinematic loops, a single path to each of the bodies from SC0
(body Base0) through a set of joints can be found, if the connectivity condition is satisfied for the
model, Chapter 2, Sect. Connectivity of systems and definition of a joint. According to UM rule,
each of the joints in this path specifies the position of the second body in kinematic pair relative
to the first one. So, there exist joints of two types.
1. A joint has a positive direction if the first body in the kinematic pair lies in the path closer
to SC0 than the second one, in particular if the first body lies in the path from SC0 to the second body. For instance, if the first body in the joint description is Base0 and the second
body is Body1, the joint has the positive direction.
2. A joint has a negative direction if the second body in the path is closer to Base0 than the
first one. For instance if the first body in the joint description is Body1 and the second body
is Base0, the joint has the negative direction.
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Consider an additional example of a chain of three bodies in the sequence Base0, Body1,
Body2. The joint connecting Body1 and Body2 is positive if Body1 is assigned as the first one
and negative in the opposite case.
There exists a number of causes related to internal realization of kinematics of multibody
systems, according to which it is not recommended to introduce joints with negative directions. Lack of logic in the case of a negative joint is clear from the following example. Consider
a rotational joint connecting Body1 (the first body) with Base0. The joint coordinate in this case
describe rotation of SC0 relative to Body1, and logically more correct is the opposite case.
The negative direction of a joint is marked as [-1] in the section of additional joint parameters, available by the
button, as well as in the Indices tab of the object inspector, Figure 3.177.
To escape joints with negative direction, it is recommended to follow the simple rules for sequence of description of joints described in Sect. 3.6.1.
Remark 1.
Remark 2.
Direction is not introduced for cut joints.
Direction of joints can be changed if the user exchanges bodies in discretion of
the joints and corrects coordinates of joint points.
Figure 3.177. Indication of joint with negative direction
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3.6.11.5. Input of rotational and translational joints
Figure 3.178. Parameters of a rotational joint
Notions of translational and rotational joints are discussed in Chapter 2, Sect. Translational
and rotational joints.
The following parameters should be entered in addition to bodies and joint points
(Sect. 3.6.10.1, 3.6.10.3):
 projections of the joint vector on axes of two body-fixed SC (the Geometry tab, Figure 3.178); the vector cannot be zero;
 additional shift and rotation (the Description tab, the Configuration group); the parameters
are optional.
If the bodies connected by the joint are in the tree (visible in the full object mode of the animation window, set the
button in the ‘down’ state to verify this), the
buttons can be used
for visual entering both the joint points and the joint vectors. A joint vectors can be obtained
from connection points of vector and oriented point types (see Sect. 3.6.10.4. Visual assignment
of bodies and attachment points). Thus, selection of a vector or an oriented point allows the user
to assign simultaneously a body, a joint point and a joint vector. If the oriented point is selected,
the vector is directed along the Z axis of LSC, specified by the oriented point.
Further description of joint depends on type of the joint coordinate. The coordinate can be a
degree of freedom or a time function.
Coordinate is a degree of freedom
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All parameters are optional:
value of the coordinate – the box is usually used to verify the correctness of the joint description: stepwise changing of the value leads to motion of bodies;
type of the joint force/torque (Chapter 2, Sect. Joint forces and torques) can be chosen from
the drop-down list on the Joint force tab, Figure 3.179, Sect. 3.6.12.2.
Figure 3.179. Types of joint force
After the type has been chosen, the boxes for force parameters appear.
Coordinate is a time function
Use the Prescribed time function check box to set this type of the coordinate.
Figure 3.180. Time function




The time function can be set as
an explicit expression (Sect. 3.5.2.4.6)
an external function (Sect. 3.5.2.4.10)
a time table (Sect. 3.5.2.4.12)
a function from a text file (Sect. 3.5.2.4.11)
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Both rotational and translational joints is recommended to be transformed to the
generalized joint type, e.g. to add degrees of freedom or to parameterize inclination of the joint axis, Sect. 3.6.11.3.
Example. User’s manual, Chapter 7, Sect. Joint type conversion. Parameterization of axis
inclination.
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3.6.11.6. Input of 6 d.o.f. joint
Detailed description of the joint can be found in Sect. Chapter 2, Sect. Six d.o.f. joint.
Figure 3.181. Description of 6 d.o.f. joint
In addition to connected bodies (Sect. 3.6.10.1), the user should set positions of local joint
system of coordinates SC1A and SC2B relative to SC1 and SC2 in the Geometry tab. For this
purpose the sheets Body1 and Body2 are used, Figure 3.181 left. The standard interface is used
for parametric setting the SC positions, see Sect. 3.6.4.
The following parameters should be entered to specify the joint coordinates (Figure 3.181,
right):
 type of orientation angles;
 “turned on” degrees of freedom (check the presented degrees of freedom and turn off the
others); the three upper rows correspond to translational d.o.f. (Figure 3.181).
Use the buttons  in the edit boxes to set initial values as well as to verify the correctness of
the joint description.
Remark 1.
Remark 2.
Cut joints with six d.o.f. are ignored in the Simulation program.
6 d.o.f. joint can be converted to the generalized type to introduce joint forces for
some degrees of freedom, Sect. 3.6.11.3.
Example. An example of a joint used for setting six degrees of freedom of a box relative to
SC0 according to data in Figure 3.181 left for x0=1m, alpha=30 degrees is shown in Figure 3.182. The box is shown in the position corresponding to zero values of joint coordinates.
Features of the joint are the parametric description of both the SC1A origin (shift along the X-
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axis x0) and angle of rotation about the X axis (alpha). As a result two translational and two rotational degrees are specified along inclines axes Y and Z.
Figure 3.182. Example of a joint with six degrees of freedom
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3.6.11.7. Input of joint of generalized type
The joint description consists of a sequence of elementary transformations (ET), Chapter 2,
Sect. Generalized joint.
Figure 3.183. Generalized joint
The list of ET is created with the help of the standard interface. To specify a type of ET use
the pull-down menu (Figure 3.183). Edit boxes for ET parameters appear after the choice of the
type.
The Enabled key allows excluding a transformation.
A unit transformation vector should be entered for all ET types except tc (the vector cannot
be zero).
Figure 3.184. Unit vector of a transformation
Use the pull-down list to set a standard value of the vector.
Cut joints with 6 d.o.f. are ignored in the Simulation program if no joint forces are presented.
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3.6.11.7.1. Elementary transformation tc
Figure 3.185. ET: translation constant
Enter a shift vector, which components are constant symbolic expressions.
3.6.11.7.2. Elementary transformation rc
Figure 3.186. ET: constant angle rotation
Angle of rotation (in degrees) must be entered in addition to the transformation vector.
Remark.
Use the rt type to set the constant rotation angle as an identifier or constant expression.
3.6.11.7.3. Elementary transformations tv, rv
Figure 3.187. ET: rotational and translational degree of freedom


The following parameters can be optionally set in addition to the transformation vector
Numeric (initial) value of the joint coordinate (the angle coordinate is entered in degrees);
use the buttons in the edit box to get the animation of motion corresponding to changing the
coordinate.
Mathematical model of a joint force/torque. Choose the force type from the list
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Figure 3.188. Types of joint force
After the type has been chosen, the boxes for force parameters appear.
3.6.11.7.4. Elementary transformations tt, rt
Figure 3.189. Time function




In addition to transformation vector enter a time function for the coordinate as
an explicit expression (Sect. 3.5.2.4.6)
an external function (Sect. 3.5.2.4.10)
a time table (Sect. 3.5.2.4.12)
a function from a text file (Sect. 3.5.2.4.11)
Remark.
Use the type rt for entering a rotation with a constant angle, which can be set as
an identifier or an explicit expression. In this case chose the Expression type of
description and enter an expression, which does not depend on time t
(Figure 3.189, left).
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3.6.11.8. Input of quaternion joint
Figure 3.190. Parameters of a quaternion joint
A detailed description of a quaternion joint can be found in Chapter 2, Sect. Quaternion joint.
The following data can be set in addition to bodies and joint points (Sect. 3.6.9.7):
 Initial orientation of the second body relative to the first one (angle is entered in degrees);
 Translational coordinates can be turned off to obtain a spherical joint;
Remark.
Cut quaternion joints with 6 d.o.f. are ignored in the Simulation program.
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3.6.11.9. Input of rod constraint
Figure 3.191. Rod joint parameters
A detailed description of a rod joint can be found in Chapter 2, Sect. Weightless rod constraint. In addition to the bodies and attachment points (Sect. 3.6.9.7), the length of the rod
should be entered. The length can be either constant of a time function.
Set a length as
 an explicit expression (Sect. 3.5.2.4.6)
 an external function (Sect. 3.5.2.4.10)
 a time table (Sect. 3.5.2.4.12)
 a function from a text file (Sect. 3.5.2.4.11)
As a rule, a graphic object is assigned to the rod (Sect. 3.6.6).
The current distance between the rod attachment points is presented in the Current length
box. Use this parameter to verify the correctness of the length description.
Remark.
The rod is a constraint. It does not introduce coordinates but restricts relative position of connected bodies. Exact calculation of positions in this case can be done
by the
button in the top of animation window or in the Simulation program.
That is why the current length of the rod in the Input program can differ from the
real length entered by the user until the constraint computation is done.
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3.6.11.10. Input of mates
Definition of mates can be found in Chapter 2, Sect. Mates.
Figure 3.192. Examples of mates
The following parameters describe a mate, Figure 3.192.
 Mate type, Figure 3.193.
Figure 3.193. Mate types

Types of the first and second manifolds,
Figure 3.194. Manifolds
Chapter 3. Data input program
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Coordinates of joint points for the first and second body in the SC of the corresponding
body. The points specify
o coordinates of the manifold of the point type;
o coordinates of the initial point of the vector manifold;
o coordinates of any point on the plane manifold.
If the manifold is a vector or a plane, projections of the vector or the normal to the plane
must be defined in the group Joint vectors. The joint vector is ignored in the case of a point
manifold.
Mates Distance and Angle require an additional parameter: the value of the distance or the
angle between manifolds, Figure 3.195.
Figure 3.195. Distance and angle parameters
The standard components Mates in Figure 3.196 are used for a visual assignment of bodies,
joint points and vectors. The following steps are necessary:
- connection points or vectors should be preliminary assigned to the bodies;
- to create a mate, click on the button with the visual component and follow the instructions.
To assign a body, a joint point and a vector, it is enough to select by the mouse a connection
point of a vector type or an oriented point, Sect. 3.6.9.6.
Figure 3.196. Standard mate components
Remark.
If mates are presented in a model, the Park Parallel numeric method cannot be
used for simulation.
Simple simulation examples with mates are available in the directory
{Path to UM}\Samples\Library\Mates
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3.6.11.11. Input of convel (CV) joint


See Chapter 2, Sect. Convel joint for a definition of the joint.
The following parameters specify the joint, Figure 3.197:
coordinates of joint points in the body-fixed CS.
projections of joint vectors in the body-fixed CS.
Figure 3.197. Example of a convel joint
Remark.
If a convel joint is presented in a model, the Park Parallel numeric method cannot be used for simulation.
Example. See Chapter 7, Sect. Convel joint.
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3.6.12. Input of force elements
3.6.12.1. Input of gravity
Use the Object | General tab of the inspector for setting the gravity force, Figure 3.198,
Sect. 3.5.2.1. Here both the direction of the gravity force and the gravity acceleration can be
changed.
Figure 3.198. Direction of gravity
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3.6.12.2. Description of scalar force and torque
Mathematical models of scalar forces are described in Chapter 2, Sect. Types of scalar forces.





The scalar forces are used by descriptions of the following types of force elements:
joint force, Sect. 3.6.11.5, 3.6.11.7.3,
scalar torque, Sect. 3.6.12.4,
bipolar force element, Sect. 3.6.12.3,
generalized bushing, Sect. 3.6.12.8.6.2,
axial force for combined friction, Sect. 3.6.12.8.7.5.
Below we consider parameters of scalar forces of different types, Figure 3.199.
Figure 3.199. Types of scalar force
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3.6.12.2.1. Linear force element
General information about force element of this type can be found in Chapter 2, Sect. Types
of scalar forces | Linear force.
Figure 3.200. Parameters of linear force element describing a linear viscous-elastic interaction
The boxes in the window (Figure 3.200) correspond to the following parameters of the element:
 F0 is constant component of the force;
 cStiff is stiffness constant;
 cDiss is damping constant;
 x0 is the coordinate for zero value of the elastic component;
 Q, w, a is amplitude, frequency (rad/s) and initial phase (rad) of the harmonic excitation.
All the parameters are constant symbolic expressions, Sect. 3.5.2.4.5.
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3.6.12.2.2. Friction and elastic-frictional elements
General information about force element of this type can be found in Chapter 2, Sect. Types
of scalar forces | Friction force and Types of scalar forces | Elastic-friction force.
Figure 3.201. Parameters of friction element




The following parameters should be specified:
friction force value F;
static/dynamic coefficient of friction ratio f0/f;
stiffness at sticking cStiff.
damping constant at sticking cDiss.
All parameters are constant symbolic expressions, Sect. 3.5.2.4.5.
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3.6.12.2.3. Elastic-frictional element 2
General information about force element of this type can be found in Chapter 2, Sect. Types
of scalar forces | Elastic-friction force 2.
Figure 3.202. Parameters of elastic-friction element 2





The following parameters should be specified:
Dynamic coefficient of friction f;
Static coefficient of friction f0 (usually a bit greater than the dynamic one);
Stiffness of the first spring c1;
Stiffness of the second spring c2;
Element length in the unloaded state.
All parameters are constant symbolic expressions, Sect. 3.5.2.4.5.
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3.6.12.2.4. Viscous-elastic element
General information about force element of this type can be found in Chapter 2, Sect. Types
of scalar forces | Stiffness and damping in series and in parallel.
Figure 3.203. Parameters of viscous-elastic element




The following parameters should be specified:
Stiffness cStiff in series (N/m), c in figure;
Damping constant cDiss (Ns/m);
Stiffness cStiff 1 in parallel (N/m), c1 in figure (can be zero);
Length of unloaded element L0 (ignored if c1=0)
Parameters are specified as constant symbolic expressions.
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3.6.12.2.5. Nonlinear viscous-elastic element
General information about force element of this type can be found in Chapter 2, Sect. Types
of scalar forces | Nonlinear spring and damper in series.
Figure 3.204. Element parameters
Description of this element includes two plots: spring force vs. deflection as well as damper
force vs. velocity. Use the
buttons to call the curve editor for defining point on plots
(Figure 3.205, Figure 3.206).
Figure 3.205. Parameterized model of linear spring
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Figure 3.206. Parameterized model of nonlinear damper
Parameterized expressions can be used as coordinate values. Spline or B-spline can be applied for plot smoothing.
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3.6.12.2.6. Points (numbers)
General information about force element of this type can be found in Chapter 2, Sect. Types
of scalar forces | Points model.
Figure 3.207. Parameters of Points (numbers) element
Curve editor is used to set a plot of the force by a set of points (Sect. 3.5.3, Figure 3.208), use
the
button to call the editor.
The force can depend on the
 coordinate x,
 velocity v,
 time t,
 variable defined by the user, Sect. 3.5.2.4.8.
Use the Type of abscissa group to select a necessary dependence.
The Factor parameter changes scale of ordinate values. Zero value of the factor, in fact, removes the element. Usually the multiplier is set by an identifier.
3.6.12.2.6.1. Force dependence on x, v, t
a)
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b)
Figure 3.208. Elastic bipolar force element with 4 mm gap; option “Positive compression” is off
(a) and on (b)
The Compression positive option is used for choice of the positive abscissa value on the
force law plot. If the option is not checked (the default value), abscissa increases with the
growth of the length (coordinate); in this case the force usually decreases with the growth of abscissa. If the option is checked, on the contrary, abscissa decreases with the growth of the length
(coordinate), and the force usually increases with the growth of abscissa.
To insert data from a text file use the clipboard (Sect. 3.5.4.7).
Abscissa matching
Abscissa matching is often used in the case of a bipolar force element, when the force depends on the element length. Matching means that abscissa value on the plot must correspond to
a definite length L of the element, which value should be set in the L edit box, Figure 3.207. Often L value is the element length for zero values of coordinates. Two methods can be used for
assignment of abscissa value to the element length according to the Type of abscissa matching
group, Figure 3.207. If the X-value option is selected, the abscissa value corresponding to L is
directly set in the X(L)/F(L) edit box. Often this value is zero, X(L)=0. If the F-value option is
selected, the force value corresponding to the length L is set, and program compute the corresponding abscissa value automatically. It is clear that in the last case the user must ensure the
existence and uniqueness of solution X(F).
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Figure 3.209. To the notion of abscissa matching.
The Compression positive option is not checked.
Figure 3.210. To the notion of abscissa matching.
The Compression positive option is checked.
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3.6.12.2.6.2. Indicator diagram
Dependence of a force on a variable created by the user is used mainly for modeling periodic
indicator diagrams; the Periodic dependence key must be checked. In the indicator diagram the
force does not depend on the current coordinate x, but on angle of rotation of another link. For
instance, x is the joint coordinate of the engine piston, and the force depends on the angle of rotation of a crank, Figure 3.211.
Figure 3.211. Example of an indicator diagram
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3.6.12.2.7. Points (expressions)
General information about force element of this type can be found in Chapter 2, Sect. Types
of scalar forces | Points model.
Figure 3.212. Elastic bipolar force element with a gap, which value is set by the gap identifier
The force element is similar to the previous one, but both abscissa and ordinate coordinates
of points can be set by expressions.
Use the
buttons to add, copy or delete a selected point. The
button is used for
preview the function in a graphical window.
In the figures of this section we consider a description of the same function as in the previous
one but the length of element, clearance, and stiffness are parameterized. Parameterization allows changing these parameters in the simulation.
Figure 3.213. Nonlinear damper. The Compression positive option is not checked.
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Figure 3.214. Nonlinear damper. The Compression positive option is checked.
3.6.12.2.8. External function
The name of the function must be entered. A template of the function will be automatically
inserted in the control file for programming by the user, Sect. 3.5.2.4.10. One function can be
used in description of several force elements.
Remark.
Using of external function requires the generation of equations of motion in symbolic form, Sect. 3.9.2.
Figure 3.215. Example of external function
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3.6.12.2.9. Expression




The force model is described by an explicit expression including
identifiers,
x, v, t – length of the element, joint coordinate or angle of rotation (depending on the force
type), its time derivative and time,
kinematic functions for positions and velocities, Sect. 3.5.2.4.7.
standard functions, Sect. 3.5.2.4.3.
Example: a combined linear spring/damper force
-cstiff*(x-x0)-cdiss*v
where cstiff, cdiss are the spring and damper constants, x0 is the length/coordinate of the unloaded element.
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3.6.12.2.10. List of characteristics
Description of the force is located in Chapter 2, Sect. Types of scalar forces | List of characteristics.
Sequence of the element description:
 set Abscissa type (coordinate, velocity of time);
 open the curve editor by the
button and create a list of curves; to start a new curve, double click by the mouse on a big enough distance from other curves and confirm creation of a
new curve; please note that curves are numbered in the input order, drag the curve name by
the mouse to change in position in the list;
 enter a Curve identifier, which value select a characteristic for computation of the force;
 if necessary, specify the scale factors kx, ky for the abscissa and ordinate values;
 set type of the curve identifier: either discrete or continuous – checked in the last case.
Figure 3.216. Example of a traction force model as a list of characteristics
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3.6.12.2.11. Fancher leaf spring
The mathematical model of the element can be found in Chapter 2, Sect. Fancher leaf spring.
Force model parameters:
Stiffness (compressed) – the spring vertical stiffness in the compressed state, c;
Stiffness (stretched) – the spring vertical stiffness in the stretched state, c;
f friction (compressed) – the value of friction coefficient in the compressed state, f ;
f friction (stretched) – the value of friction coefficient in the stretched state, f ;
Beta - the exponential suspension parameter,  ;
Height – the height of the spring in the unloaded state
x0 .
All the parameters are constant symbolic expressions.
Figure 3.217. Parameters of leaf spring
Remark.
The user should remember that bipolar force elements degenerate at zero length.
The lengths of the Fancher elements in the model of the leaf spring must be at
least two times greater than the maximal dynamic shortening the element even if
the real prototype has a less height.
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3.6.12.2.12. Hysteresis
Mathematical model of the force is described in Chapter 2, Sect. Types of scalar forces / Hysteresis.
Figure 3.218. Example of hysteresis data input window
Compression
Stretching
Figure 3.219. Example of hysteretic element with symmetric operation relative to length 1 m
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The Type of element operation group:
o stretch(ing) is the element works only if coordinate value is greater than the value in
the L box;
o compress(ion) is the element works only if coordinate value is less than the value in
the L box;
o symm(etric) is the element works symmetrically both by stretching and by compression.
The L box contains the element length/coordinate value corresponding to the zero value of
abscissa of points. The buttons of operations with the list of points
delete selected point, copy selected point, and draw data in the graphic window.
– add a point,
6
4
7
1
5
3
2
Figure 3.220. Graphic window with hysteresis data
Coordinates of points can be parameterized.
Indices of points starting with 1 separated by commas for hysteretic curves are entered in the
lowest table of the data window. Orders of interpolation polynomials are set in the last column of
the table (order 1 corresponds to a polyline).
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More details about hysteretic element can be found in Chapter 2, Sect. Types of scalar forces
/ Hysteresis.
3.6.12.2.13. Impact (bump stop)
Figure 3.221. Parameters of an impact element
Mathematical model of the force element of this kind is described in Chapter 2, Sect. Impact.
The model has the following parameters:
L is the length of the element at zero clearance when force element starts to work, l;
cStiff is a stiffness coefficient in a contact, c;
cDiss is a damping coefficient in a contact, d;
dLDiss is the contact deflection where damping coefficient reaches its maximal value cDiss,
d
;
eStiff is the force curve exponent, is not used in the current version of UM software, assumed
to be 1.
All the parameters are constant symbolic expressions.
This force element can works as a border for compression and stretching modes. Let us consider the compression case. While the length of the force element more or equal to L than force
is zero. As soon as the length of the element becomes less than L, the viscoelastic force starts to
act. In the case of the stretching mode the force starts to act if the length of the element exceeds
L.
If force element of Impact type acts as a joint force, the L parameter should be considered as
a joint coordinate. Thus, introducing two forces of this type (one for stretching, another one for
compression) as joint forces in a joint, we can define limits for the joint coordinate.
Dimensions of parameters for bipolar and joint forces are given in the table below.
Parameters
L
cStiff
Dimension
Bipolar of joint force along Joint force along rotational
translational degree of free- degree of freedom
dom
m
rad
N/m
Nm/rad
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Nms/rad
rad
3.6.12.2.14. Ratchet
Figure 3.222. Parameters of a ratchet
Mathematical model of the force element of this kind is described in Chapter 2,
Sect. Ratchet.
The model has the following parameters:
cStiff is a stiffness coefficient while locking, c;
cDiss is a damping coefficient while locking, d;
dLDiss is the contact deflection where damping coefficient reaches its maximal value cDiss,
d
;
eStiff is the force curve exponent, is not used in the current version of UM software, assumed
to be 1.
All the parameters are constant symbolic expressions.
Units of the parameters depend on the unit of the x coordinate, Sect. 3.6.12.2.13.
Models:
{UM Data}\SAMPLES\LIBRARY\Ratchet;
{UM Data}\SAMPLES\LIBRARY\ChainGear.
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3.6.12.2.15. Library DLL
a)
b)
Figure 3.223. Examples of scalar forces described with dynamic libraries
The force realizes an access to the models and parameters of scalar forces described in dynamic linked libraries and located in the directory {UM Data}\lib\bfrc.
See Chapter 2, Sect. Scalar force of Library (DLL) type as well as Chapter 5, Sect. Scalar
force of Library (DLL) type
Examples of Delphi projects:
{UM Data}\SAMPLES\LIBRARY\DLL\BfrcSample, Figure 3.223a,
{UM Data}\SAMPLES\LIBRARY\DLL\BfrcSample1, Figure 3.223b.
Parameters of force elements are constant symbolic expressions, Sect. 3.5.2.4.5.
3.6.12.2.16. List of forces
Figure 3.224. Example of a list of two forces
This type of force creates an arbitrary set of forces of the above types, which work in parallel. Use the
buttons to add, copy or delete a separate force.
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3.6.12.3. Input of bipolar force elements
Definition of a bipolar force element can be found in Chapter 2, Sect. Bipolar forces.
General parameters of a bipolar element are:
 Connected bodies;
 Attachment points (constant symbolic expression);
 Type (use the drop-down list).
Other parameters of the element depend on its type and should be entered in boxes, which
appear after choice of the type. Some features of description of the force as an explicit expression can be found in Sect. 3.5.2.4.6, as an external function – in Sect. 3.5.2.4.10.
Mathematical model of a bipolar force includes often the element length (the distance between the attachment points). Use the current Length parameter to verify the correctness of description of the element.
A GO is usually assigned to the bipolar force (Sect. 3.6.6).
Figure 3.225. Bipolar force element
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3.6.12.4. Input of scalar torque force element
Mathematic model of the element is described in Chapter 2, Sect. Scalar torque. Description
of a scalar torques includes the following steps.
 Choice of interacting bodies.
 Setting additional local coordinate systems SCA1 and SCB2, Figure 3.226, left. These systems of coordinates can be assigned visually by the mouse using preliminary created oriented connection points for the necessary bodies, Sect. 3.6.9.6.2. Systems of coordinates are
drawn in animation window like in Figure 3.226, middle. If the Autodetection mode is selected, position of SCB2 is computed by the program automatically: SCB2 coincides with
SCA1 for zero values of all coordinates.
 Selection of the torque type from the standard list of scalar forces, see Sect. 3.6.12.2 for
more details.
Figure 3.226. Scalar torque description
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Figure 3.227. Example of scalar torque
Figure 3.228. Nonlinear elastic torque component
Example. Consider an example of usage of the scalar torque. In a model of a locomotive, a
scalar torque appears when a car body turns relative to the bogie frame about the vertical axis,
Figure 3.227. The torque includes two components. The first one is a friction torque with the
magnitude 2000Nm. The second one is a nonlinear elastic torque, which plot is shown in Figure 3.228, left. In this case the torque type is ‘List of forces’. The list of forces includes two elements: a frictional (Figure 3.226, right) and ‘Points symbolic’, Figure 3.228, right.
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3.6.12.5. Input of generalized linear force elements
3.6.12.5.1. General information on generalized linear force elements
Figure 3.229. Parameters of Linear force element
Mathematic model of the element is described in Chapter 2, Sect. Generalized linear force
element.
Examples of description and/or usage:
 Chapter 7, Sect. Models of Springs
 model {UM Data}\SAMPLES\Rai_Vehicles\Manchester_Benchmarks\Vehicle1 (module
UM Loco is required);
 model {UM Data}\SAMPLES\Rail_Vehicles\wedgetest.
General parameters of a linear element are:
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



Adjusted bodies;
Geometric parameters on the Position tab;
Elements of stiffness and damping matrix (use the button in the corresponding box).
Stationary force value
A GO is usually assigned to the linear elastic force (Sect. 3.6.6).
Coordinates of attachment points as well as elements of the stiffness/damping matrix are parameterized.
3.6.12.5.2. Some features of description of elastic element
Figure 3.230. Systems of coordinates related to linear force
Some details relevant to the elastic force element can be found in Chapter 2,
Sect. Generalized linear force element. There can be found notations used in figures as well.

The following parameters should be entered for the first body attached to the element:
Coordinates of points A, B1 in SC of the first body;
For the second body (if the option Automatic computation for 2nd body is off):
 Coordinates of point B2 in SC of the second body;
 Orientation of SC connected with point B2 relative to the SC of the second body (use up to
three rotations). If the orientation does not set, the SCB2 coincides with SC of the second
body.
These data are not necessary for the second body if the Automatic computation for 2nd body
option in on. This option is used exclusively if the object is described in such a way that points
B1 and B2 coincide at zero values of model coordinates. This case is quite usual for models of
railway vehicles.
If you click the Compute for the second body button, UM computes coordinates of point B1
in SC of the 2nd body and inserts these values as coordinates of point B2 (even if the Automatic
computation for 2nd body is off).
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The stationary value of the force acting on the second body can be entered, too. The force is
resolved in SC of the first body.
Coordinates of attachment points, components of stationary force, and elements of the element matrix are parameterized.
Remarks:
1. Points A, B1, B2 as well as systems of coordinates attached to them are visualized in the
single element mode (Sect. 3.5.1.2.2). The icon marks point B1.
2. These points are visualized in the whole object mode if the corresponding option is chosen
(Sect. 3.5.1.2.2). Click the icon to call the window with element parameters.
3. Use general and oriented connection points (Sect. 3.6.9.6) to set points A, B1, B2 together
with the attached SC. The connection points must be preliminary added to the corresponding body. The
buttons start the mode of visual selection of connection points.
3.6.12.5.3. Bilinear force element
Figure 3.231. Parameters of bilinear force element
A bilinear force element consists of two springs. The second spring is shorter than the first
one.
Additional parameters are related to the second spring
 stiffness matrix of the shorter second spring Matrix 2,
 difference in the heights of the springs in meters.
The shorter spring begins to act when the compression of the first spring including the static
deflection is greater than the height difference. Otherwise, the force from the second spring is
zero.
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3.6.12.6. Input of contact force elements
Use the Contact forces tab for description of the list of contact forces (Chapter 2,
Sect. Contact forces).









Types of a contact force element:
Points-Plane;
Point-Curve;
Circle-Cylinder (with curved axis);
Sphere-Plane;
Circle-Plane;
Sphere-Sphere;
Points-Z surface;
Circle-Z surface;
Sphere-Z surface.
Remark.
Changing the type deletes all previous description of the element.
The first interacting body always contains the first type of contact manifold in the name of
the contact. For instance, the first body contains points and the second one – a plane in the case
of the Points-Plane contact.
There exist two tabs for description of an element:
 The Parameters tab contains some general contact parameters such as static and dynamic
friction coefficient, contact stiffness and damping coefficient etc.;
 The Geometry tab contains parameters depending of the element type.
3.6.12.6.1. Coefficient of friction, stiffness, damping at contact
Figure 3.232. Parameters of contact friction
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Model of friction is considered in Chapter 2, Sect. Contact forces | Dependence of coefficient
of friction on sliding velocity.
Independently on the type of contact interaction, the coefficient of friction is specified on the
Parameter tab:
 f is the coefficient of friction for infinite sliding velocity f  ;







f
f0 is the coefficient of friction for zero sliding velocity 0 (static coefficient of friction)
vs is the Stribeck velocity;
delta is the empirical exponent depending of materials,   [0.5, 1] ;
nu is the viscous friction constant;
Additional parameters relates to the rolling contact (not used for contacts of points):
Kroll (m) is the rolling coefficient of friction;
Kspin (m) is the coefficient of pivoting friction;
v* is the regulatory sliding velocity (see Charter 2, Sect. Contact forces | Other types of
contact forces).
Two constants are used for computation of the normal force in dependence on penetration
distance and velocity
 C is the stiffness constants;
 D is the damping constants.
Detailed information about rational choice of the contact stiffness and damping constants can
be found in Chapter 2, Sect. Methodology of choice of contact parameters.
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3.6.12.6.2. Points-Plane contact
Figure 3.233. Parameters of ‘points-plane’ contact force
Contact points belong to the first body, and the plane to the second one.
3.6.12.6.2.1. Contact geometry
Figure 3.234. Geometry of points-plane contact
Parameters on the Geometry tab describe points and plane data, Figure 3.234.


The plane belongs to the second body; it is described by the following parameters:
a point is any point on the contact plane specified by its coordinates in the SC of the second
body;
external normal is the vector of the normal to the plane; in the case of an unilateral contact,
the vector in directed outside of the contact.
In the single element mode of the animation window (Sect. 3.5.1.2.2), the normal vector is to
verify the correctness of its direction.
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There is three methods for entering contact points:

by keyboard on the Geometry tab, the buttons


visually by the body image, the button
from a text file, the button .
,
,
Visual input of contact points
The visual input is available if the mode of element selection by the mouse as available, i.e. if
the
button on the tool panel of the animation window is in the ‘down’ state.
 It is recommended to define for the body a set of connection point corresponding to the contact points, Sect. 3.6.9.6.
Figure 3.235. This button starts visual mode


Start the mode of visual selection of points by the
button on the inspector, Figure 3.235.
Use the body image in the animation window and the left mouse button to select the contact
points and their adding to the list in the Geometry tab. Any number of contact points can be
selected both with the help of the preliminary created connection points, and by a simple
click on the body image.

Click again the
button to break the mode.
Input contact points from a test file
A set of contact points can be read from a test file by the
button in the inspector. The file
must contain three columns of x,y,z coordinates of contact points.
3.6.12.6.2.2. Close contact
Figure 3.236. Parameters of close contact
Check the Close contact key for autodetection of the plane parameters such as the plane
normal and point, Figure 3.236.
In the autodetection mode, the first contact point as considered as the point on the plane. The
autodetection of the normal requires
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at least three contact points; the plane passes through the first three contact points for zero
values of object coordinates, and the normal direction is detected by the right-hand screw
rule; change the sequence of points in the list to get an opposite direction of the normal;
checked the key Autodetection of normal.
In the close contact mode, a gap and a deviation of the normal from the detected position can
be specified for zero coordinates of the object.
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3.6.12.6.2.3. Unilateral and bilateral contact
In the unilateral mode, the contact force appears if the contact point penetrates the contact
plane in the direction opposite to the plane normal, otherwise the force is zero.
In the bilateral mode, the force appears by deviation of the point in both directions on a distance, which is greater than the gap specified by the user. Therefore, if the gap is non-zero, in
fact, two contact planes are presented with the distance between them equal to the double gap. In
a particular case, the gap can be zero.
3.6.12.6.2.4. Limited contact plane
Figure 3.237. Mode of limited contact plane
The checked Unlimited plane key states that the contact plane has no limits. Otherwise, an
additional tab Limits appears (Figure 3.237), which allows the user to describe the geometry of
the contact area on the plane by its bounds as
 a rectangle,
 a circle,
 a curve specified by a set of points with a possible smoothing by splines and circle arcs.
The bounds of the contact area are drawn in the animation window in the single element modem Sect. 3.5.1.2.2, which allows the user to control the correctness of data. If necessary, the
curve can be turned in the plane on a definite angle in degrees according to the value in the Rotation about normal box.
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Figure 3.238. Different bounds of the contact area
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3.6.12.6.2.5. Locking contact
Figure 3.239. The locking mode of bilateral contact
In the case of a bilateral contact, a locking contact mode is available, Figure 3.239. At the
begin of the simulation the contact force is zero if the contact point is located in the positive part
of the half-space defined by the contact plane and the normal to it, like in the case of an unilateral contact. By the first penetration of the contact point into the plane, the contact become a bilateral one with a possible gap between the contact planes, i.e. the contact is locked up to the end
of the simulation.
The most frequent example of use: a collision of rail vehicles with the following locking the
automatic couplers.
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3.6.12.6.3. Point-Curve contact
Figure 3.240. Parameters of Point-Curve contact
The mathematical model of the curve-plane interaction is described in Chapter 2, Sect. Force
elements | Contact forces| Point-Curve contact.
Body with the contact points must be assigned as the first one, and the curve as connected
with the second body.
The following parameters are set on the Geometry tab, Figure 3.240:


coordinates of the contact point, which can be assigned visually by the
button; the corresponding connection point must be preliminary assigned to the body, Sect. 3.6.9.6;
preliminary created curve from the list of 3D curves, Sect. 3.6.7.
Figure 3.241. Curve in the animation window
The contact curve is drawn automatically in the animation window, Figure 3.241. In the single element mode of the animation window, the contact point as well as the nearest point to the
contact on the curve are drawn.
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It is not necessary that the contact point lies on the curve in input module. It must
be done in the simulation module by a special tool during assignment of initial
coordinates.
3.6.12.6.4. Contact of circle with cylinder (curved axis)
Figure 3.242. Parameters of Circle-Cylinder contact
The mathematical model of the curve-plane interaction is described in Chapter 2, Sect. Force
elements | Contact forces| Contact of circle with cylinder with curved axis.
Body with the circle must be assigned as the first one, and the cylinder as connected with the
second body.

The following parameters are set on the Geometry tab, Figure 3.240:
coordinates of the circle center point in SC of the first body, which can be assigned visually
by the
button; the corresponding connection point must be preliminary assigned to the
body, Sect. 3.6.9.6;
 radius of the circle and the normal to the circle plane;
 radius of the cylinder, which must be greater than the circle radius;
 preliminary created curve from the list of 3D curves, Sect. 3.6.7;
After assignment of parameters, the cylinder is automatically drawn in the animation window, if the Draw cylinder option is checked, Figure 3.243. In the single element mode of the
animation window, the circle and the normal are drawn as well.
The automatically generated image of the cylinder consists of a series of circles perpendicular to the axis. Centers of the circles lie of the axis curve. Number of circles is specified by the
user as the Number of points in plot parameter, Figure 3.244.
If contacts of several circles with the same cylinder are modeled, the Draw cylinder key is
recommended to be unchecked to avoid the multiple drawing the cylinder.
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Figure 3.243. Cylinder image
Figure 3.244. Description of the curve, which is the axis of cylinder in Figure 3.243
Model: {UM Data}\SAMPLES\LIBRARY\CylCircle.
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3.6.12.6.5. Sphere-Plane contact
Figure 3.245. Geometric parameters of sphere-plane contact


The contact sphere corresponds to the first body. The sphere is described by
Center (a point in SC of the first body);
Radius.
These data are parameterized.
The plane parameters are described in Sect. 3.6.12.6.2.1.
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3.6.12.6.6. Circle-Plane contact
Figure 3.246. Geometric parameters of circle-plane contact



The contact circle belongs to the first body. The circle is described by
Center (a point in SC of the first body);
Radius;
Normal to the circle plane (in SC of the first body).
The plane parameters are described in Sect. 3.6.12.6.2.1.
All the data except the normals are parameterized.
3.6.12.6.7. Sphere-Sphere contact
Figure 3.247. Parameters of sphere-sphere contact


The element description contains parameters for two body-fixed spheres
Center (a point in SC of the corresponding body);
Radius.
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These data are parameterized.
There exist two types of the contact, Figure 3.247:
one sphere is outside the another one (the internal contact key is not checked)
one sphere is inside the another one (the internal contact key is checked)
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3.6.12.6.8. Points | Sphere | Circle - Z surface contact
Figure 3.248. Parameters of contacts with a Z surface
The contact points / sphere / circle belong to the first body.
A points-surface contact element includes any number of contact points like in
Sect. 3.6.12.6.2.1. No bilateral, locking a close contact modes are available for this type of interaction.
Sphere is described with the help of its center and radius. Circle is described with the help of
its center, radius and normal to its plane.
A Z-surface belongs to the second body. The surface function corresponds to the second
body and can be described by
 An explicit expression z = z(p1, p2), p1, p2   , ;


An external function z = z(p1, p2), which should be programmed in the Control file
(Sect. 3.5.2.4.10).
A Graph[ical] object which is selected in the drop down list of graphical objects in the
model.
Graphical element of Polyhedron type
Graphical element of ASC
type
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One complex
graphical object
for contact zsurface
Figure 3.249. Examples of graphical objects for z-surface



2
Please note the following things using z-surface as a Graph[ical] object.
Selected graphical object can include one or several graphical elements of Polyhedron,
ASC2, Box, Ellipsoid, Cone, Z-surface.
In the case if there are several possible z-coordinates for any (x, y) point the biggest zcoordinate will be considered.
It is desirable that graphical object be smooth enough. Using essentially non-smooth surfaces might lead to incorrect results of simulation.
Graphical objects of ASC type are created automatically during model import from external CADprograms
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3.6.12.7. T-forces
Figure 3.250. Example of a harmonic following force




Use the T-Force tab to enter a set of force elements of T-type. An element is described by
A pair of interacting bodies;
A reference body for the force/moment components;
A point the force is applied to (a point of the second body in the SC of this body); the
button allows the visual setting the second body as well as the point of application using
connection points (Sect. 3.6.9.6. Connection points).
Type of the force description Expression or File
Remark.
To describe a following force, set Base0 as the first body, and the reference body
coinciding with the second one, figure 3.250.
3.6.12.7.1. Expression type of T-Force
In this case, the force and moment components are symbolic expressions including identifiers, standards functions of time t as well as kinematic functions.
Example. Description of a following harmonic force directed along Z-axis of the body1fixed SC and applied to the point (pos_x, pos_y, 0) is shown in Figure 3.250.
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3.6.12.7.2. File type of T-Force
Figure 3.251. File description of T-force
The force components can be described by a text file. The file format is the following: the
first column contains values of time in seconds. Other columns contain optionally forces and torques in the sequence Fx, Fy, Fz, Mx, My, Mz in N and Nm. Any components can be omitted.
For instance, the file can contain three columns t, Fz, Mx.
The button
is used for selection of the file. After the selection, the file is copied automatically in the model directory. The user must check the available components in the inspector. For
instance, the file in Figure 3.241 contains the component Fz of the force.
During the simulation, a linear interpolation is used for evaluation of the force and moment
component values.
The button shows the plots of non-zero components of the force in a graphic window.
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3.6.12.8. Special forces







The following types of forces are considered in this section:
Gearing
Chain gear
Cam
Spring
Rack and pinion
Bushing
Combined friction
3.6.12.8.1. Gearing
Figure 3.252. Gearing parameters


A gearing is described by (Figure 3.252)
Attachment points (centers of gears in SC of the corresponding bodies);
Gear axes (unit vectors in SC on the bodies);
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Gearing parameters: gear ratio, clearance (optionally), stiffness and damping coefficients
of tangential contact of teeth.
Check the external/internal option for plane gearing.
All the data except the gear axes are parameterized.
Gear axes and gear circle are visualized in the single element mode (Sect. 3.5.1.2.2), Figure 3.253.
Figure 3.253. Visualization of gearing
Models:
{UM Data}\SAMPLES\LIBRARY\Gears;
{UM Data}\SAMPLES\TUTORIAL\Crusher.
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3.6.12.8.2. Chain gear
Figure 3.254. Chain gear parameters




The chain gear is described by (Figure 3.254)
Attachment points (centers of gears in SC of the corresponding bodies);
Gear axes (unit vectors in SC on the bodies); the vectors must be either parallel or nearly
parallel;
Gear radii
Stiffness and damping coefficients of the chain by stretching;
Use the Visualization option for automatic drawing the chain in the animation window, Figure 3.255.
Figure 3.255. Model with (left) and without drawing the chain
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All the data except the gear axes are parameterized.
Gear axes, circles and chain are visualized in the single element mode (Sect. 3.5.1.2.2), Figure 3.256.
Figure 3.256. Visualization of chain gear
Model (Figure 3.255): {UM Data}\SAMPLES\LIBRARY\ChainGear.
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3.6.12.8.3. Cam
A plane cam connection is realized as a variant of a contact interaction of two bodies, see
Chapter 2, Special forces/Cam.
Example of using: model {UM Data}\SAMPLES\Mechanisms\cams.
Figure 3.257. Cam parameters
The cam-piston parameters are presented in the Figure 3.257. The mathematical model of
such the interaction is similar to the contact interaction described in Chapter 2, Sect. Contact
forces. To create a cam element, select the Special forces item in the element tree and add a new
element. Set the type of the special force as Cam. As a result the inspector shows some boxes for
the parameters of the cam (Body 1) and for the piston or the link (Body 2). The user should enter
the following parameters:
 Characteristic points in SC of each body. The first point is a point of a cam profile plane
(if the profile is not imported from the body image). The second one is a point of contact
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(contact type Point), the center point of a roller (contact type Roller) or a point on a contact
plane (contact type Plane);
Profile of the cam can be chosen as one of the graphic elements in the body 1 image (From
body image) or as a planar closed curve created with the Curve editor (Set separately).
Use the Unilateral contact flag to choose either unilateral or bilateral type of the contact;
Set the point, normal to the profile plane and angle of rotation about the normal to define
the location of the separately defined profile in the SC of body1;
Cam profile can be chosen as one of the graphic elements in the body 1 if the image contains one of the following GE:
o cone, if the top and the bottom radii are equal;
o ellipse with equal semi-axes (circle);
o element of the profiled type (Curve 2D profile type, axis should be a straight line),
see. Sect. 3.6.8.2.8.
Piston parameters. Here the user can set dynamic and static coefficients of friction (except
the Roller contact type), coefficients of contact stiffness and damping as well as the radius
of the roller (contact type Roller).
Additional parameters for the Plane contact type
o external normal to the piston plane;
o type of contact Sliding/Rolling; the Rolling contact type, in particular, allows modeling the rolling of non-circular wheels on a plane.
All of the data except the normals and points on the cam profile points can be parameterized.
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3.6.12.8.4. Spring
The mathematical model of the element is described in Chapter 2, Sect. Special forces/Spring, Generalized linear force element.
Examples of description and/or usage:
o Chapter 7. Sect. Models of Spring;
o {UM Data}\SAMPLES\Rail_Vehicles\ac4 (requires UM Loco).
Coordinates of point A
Coordinates of point B2
Orientation SCB2
Figure 3.258. Spring parameters
Description of spring parameters similar to that for a generalized linear force element to a
considerable extent, namely:
 coordinates of points A, B2,
 orientation of SCB2,
 usage of the Compute for the second body button and the Autocomputing for 2nd body option,
 stationary force.
It is supposed therefore that the user have already studied input of generalized linear force element, Sect. 3.6.12.5.
Here we consider some features of the spring description only.
1. Some equivalent information is entered instead of the point B1: direction of the spring axis
in SC of the first body (radio group Direction) and the length of the spring under the static
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load, which is set in the Stationary force group. If this force is zero, the length of free
spring is set.
On the Parameters tab:
Value of a stationary force, i.e. the force value for zero coordinate values and for the given
spring length;
Type of the spring description:
o Equivalent beam: computation of stiffness parameters according to the theoretical
formulas described in Chapter 2 for the given basic spring parameters (wire diameter,
spring radius, number of active coils and so on); the button is used for getting plots
of the shear and bending stiffness in dependence on the axial spring compression.
o Experiment: spring stiffness are set as constant values, which can be parameterized as
in figure above, or variable values in pointwise dependence on the spring axial compression; the
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button calls a curve editor for plot description.
The following stiffness parameters are specified:
shear (lateral) stiffness Cs,
longitudinal (axial) stiffness Cl,
bending stiffness Cphi,
torsion stiffness Ca.
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3.6.12.8.5. Rack and pinion
Rack and pinion is a particular case of a gearing.
Figure 3.259. Rack and pinion parameters




The following parameters describe rack and pinion mechanism, Figure 3.259.
Attachments points in SC of connecting bodies: center of pinion and point on the axis of the
rack.
Unit vectors along the pinion and rack axes (rotation and translation axes respectively).
Pinion radius.
Contact stiffness and damping parameters.
All parameters except unit vectors can be parameterized.
Example. Use of the rack and pinion force element in a car steering system is shown in Figure 3.260 (see the car model {UM Data}\SAMPLES\Automotive\Vaz21_09).
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Figure 3.260. Rack and pinion in the car steering system
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3.6.12.8.6. Bushing
The mathematical model of the element is described in Chapter 2, Sect. Special forces| Bushings.
Figure 3.261. Example of a bushing: model of a car VAZ21_09 from directory Samples/Automotive
In the single element mode of the animation window, the bushing is drawn as a red wired
cylinder. SCB1 and SCB2 are drawn as well, Figure 3.261.


To describe a bushing
set positions of SCB1 (Body 1) and SCB2 (Body 2) with a standard interface for specifying
positions of local system of coordinates;
select element type Linear/Pointwise/Generalized.
Remark.
The autodetection mode is often used by description of bushings. At this mode,
SCB2 is automatically detected by positions of SCB1 for zero value of object coordinates.
3.6.12.8.6.1. Parameters of linear and pointwise bushings
In case of linear bushing: enter stiffness and damping constants for shifts (CX, CY, CZ) and
rotations (CAX, CAY, CAZ) relative to axes of CSB1.
In case of pointwise bushing: enter damping constants and nonlinear plots for force and
torque components versus the corresponding displacements and rotations.
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c)
Figure 3.262. Linear bushing: compliant ball joint (a) Pointwise bushing. Autodetection mode is
on (b). c) Position of SCB1
F ,M
If necessary, static values of force and torque 0 0 (FX, FY, FZ, MX, MY, MZ) and/or
r , 0
static offset for SCB2 0
(d_x, d_y, d_z, d_ax, d_ay, d_az) are specified.
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Figure 3.263. Example of a pointwise bushing, which is used for modeling support and gaps between a side frame and an axle-box in the model of a three-piece bogie of a freight car
Remark.
The following agreement about signs is assumed by description of pointwise
force and torque components. Positive value of elastic force/torque in a plot corresponds to positive value of displacement/rotation, see the above plot.
3.6.12.8.6.2. Description of generalized bushing
Figure 3.264. Example of generalized bushing
In the case of a generalized bushing, the user specifies projections of force and torque in
SCB1, Figure 3.264. Any type of scalar force can be assigned to the components, Sect. 3.6.12.
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This property of the generalized bushing makes it one of the most powerful tools for description
of force interactions in UM.
Models:
{UM Data}\SAMPLES\LIBRARY\Bushing\Bushing general;
{UM Data}\SAMPLES\LIBRARY\Bushing\Bushing general Ext.
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3.6.12.8.7. Combined friction
The combined friction is a generalization of the point-plane contact. Full description and the
mathematical model of this force element can be found in Chapter 2, Sect. Force elements | Special forces | Combined friction.
Examples of usage:
Directory {UM Data}\SAMPLES\LIBRARY\CombFriction, models:
CF2D_without_fict;
CF2D_with_fict;
CF2D_with_fict_limit_fict;
CF2D_with_fict_limit_body2.
The following steps are required for development of the element and setting element parameters.
Creation of a new element of the “Combined friction” type
3.6.12.8.7.1. Creation of element



To create a combined friction force element
open the list of special forces;
add a new force;
set its type as Combined friction.
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N
Body2
F
B
r
n
A
x
e
Body1
Figure 3.265. Scheme of the force element
3.6.12.8.7.2. Choice of a pair of bodies and setting the attachment point
Bodies and attachment points (point A for the first body and point B for the second one, Figure 3.265) are specified in a standard manner, see. Sect. 3.6.10.1, 3.6.10.3, 3.6.10.4.
3.6.12.8.7.3. Specifying element axis
Figure 3.266. Element axis
Element axis is set in numerical form (Figure 3.266) by a unit vector n in SC of the first
body, Figure 3.265.
3.6.12.8.7.4. Assignment of image
Image of the element is selected from the preliminary created list of graphic objects. Image
of the element should be created according to the method described for the bipolar force element,
Sect. 3.6.6.
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Figure 3.267. Image of combined friction force element by shifts of the second body relative to
the first one
As opposed to the bipolar force element, the image in this case does not connect two points
of Body1 and Body2. It is oriented along the element axis n, Figure 3.267. Moreover, in the case
of a unilateral element, the user can specify a visual lifting of the second body from the element.
3.6.12.8.7.5. Setting axial force model
Figure 3.268. Setting axial force model and parameters
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The model of an axial or a normal force N is described of the Axial force tab. The user
should select one of the possible types of the scalar force description and set its parameters,
Sect 3.6.12.1.
3.6.12.8.7.6. Friction force parameters
Figure 3.269. Friction force description
Parameters specifying the friction force should be set on the Friction tab. The user must set
 dynamic coefficient of friction (f);
 static coefficient of friction (f0);
 stiffness constant in the sticking mode (cStiff);
 damping constant in the sticking mode (cDiss).
See Chapter 2, Sect. Force elements | Contact forces | Points-Plane and Points-Z-surface
types for additional information.
3.6.12.8.7.7. Setting force element modes
Figure 3.270. Element mode keys
Use the Options tab to set a number of keys specifying the force element modes.

3D
Figure 3.271. Friction axis in 2D mode
In the 3D mode, the friction force lies in the plane perpendicular to the element axis n. If 3D
key is off, the element is in 2D mode, when the friction is directed along the fixed axis (axis of
friction) relative to Body2. The friction axis is specified by a unit vector e, Figure 3.271.
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Restrictions on shift of the fictitious body (FB) relative to Body1 of Body2 relative to the FB are not available in 3D model of the element.
Unilateral axial force
Figure 3.272. Setting the maximal length of element
If this key is on, the unilateral contact takes place, i.e. forces vanish if the normal force is
negative. The user can define the maximal length of the element in this mode. Note that this parameter influences on the element image only, and does not affect the force values. Namely, the
element length in animation window will not stretched more than the specified value, Figure 3.267.
If the key is off, the element becomes a bilateral.

Point belongs to the second body
b)
c)
Figure 3.273. Position of the normal force by shift of the second body. The contact point belongs
to the first body (b) or the first body (c)
The contact point can belong either to Body2 (if the key is on) or to Body1 the key is off.
This key does not affect the forces value, but it specifies the position of the normal force N by
shifts of the body2 relative to Body1. If the contact point belongs to the first body, it is fixed relative to Body1 and directed along the axis n. If the point belongs to the second body, the force N
moves in the lateral direction together with Body2, but still parallel to n.

Fictitious body
If the key is on, the model includes a fictitious body (FB), which can move relative to the
first body in lateral directions. The second body is in the contact with the FB.
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Figure 3.274. Parameters of viscous-elastic connection of FB with Body1
A linear viscous-elastic force appears by lateral shifts of the FB relative to Body1, which
constants should be specified by the user.
More 1information about the FB can be found Chapter 2, Sect. Force elements | Special
forces | Combined friction.

Clearance
Figure 3.275. Parameters of clearance (gap)
This option is available in 2D mode of the element with the FB. If the key is on, the Clearance tab with additional parameters appears.
Clearance introduces a restriction on the lateral shift of the FB relative to Body1 or Body2
relative to the FB.
Limit values of the shift must be set in the Min, Max boxes. See Chapter 2, Sect. Force elements | Special forces | Combined friction for more details.
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3.7. UM Components
3.7.1. Basic notions
UM components give an efficient tool for development of models. A component helps to add
to a model a fully parameterized element or a group of elements with preliminary specified properties. During the visual adding a component, the user should define necessary geometric information with connection points like attachment points of a force element, Sect. 3.6.9.6.
The following elements and substructures can be converted into a component form:
 body with/without image
 joint with/without image
 force element with/without image
 images
 subsystem
 object
If an image is assigned to an UM element like a body or a force element, the element can be
included in the component together with the image.
Two files are assigned to any UM component: a text file with description of the component
in UM format, and a bitmap (*.bmp) file with the component icon.
The standard extensions for the component text files are
 Joints: *.jnt
 Bodies: *.bdy
 Bipolar force elements: *.bfc
 Images: *.img
 Subsystem (UM object): *.sbs
 Generalized linear force element s: *.lfrc
 Contact forces: *.cfrc
 General type forces: *.afrc
 Special forces: *.sfrc
Each UM component can be parameterized. The corresponding identifiers and their default
values are included in the component description file.
An example of a file with component including element image
with const;
cnst=(mbody, 100, "Mass");
cnst=(ibodyx, 12, "Moment of inertia X");
cnst=(ibodyy, 10, "Moment of inertia Y");
cnst=(ibodyz, 15, "Moment of inertia z");
cnst=(xcg, 0, "Center of gravity X");
cnst=(ycg, 0, "Center of gravity Y");
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cnst=(zcg, 0.5, "Center of gravity Z");
cnst=(a, 0.3, "Depth");
cnst=(b, 0.4, "Width");
cnst=(c, 0.7, "Height");
with go;
name="Body image";
with ge; type= BAR;
VisibleSide=vsFront; material=6520998,6520998,0,0,10,1;
width=1;
discret=1; box=a,b,c;
with body1; name="Body"; igrobj=1;
m=mbody; ixx=ibodyx; iyy=ibodyy; izz=ibodyz; rcx=xcg; rcy=ycg; rcz=zcg;
Figure 3.276. Component panel
A set of component can be grouped in a component library, which description is stored in a
*.umc file. A tab on the tool panel corresponds to each of the linked component libraries. The
library tabs or the list of component window are used for both visual and non-visual adding to
the active object all elements included in the component.




The following component libraries are delivered with UM:
UMComponents: a set of standard forces and joints;
Mates: a set of standard mate components, Sect. 3.6.11.10;
Car|Wheels standard component of the UM Automotive module if the module is available in
the UM configuration, see the file 12_UM_Automotive.pdf;
standard component of UM Loco module if the module is available in the UM configuration, see the files 08_UM_LOCO.pdf, 17_UM_TRAIN3D.pdf.
The user may create own libraries of components to create a database of elements.
The button
is visible in the visual mode otherwise it is invisible. To switch between the
modes
o click the right mouse button on the tab with components;
o use the Visual design menu command in the pop-up menu.
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3.7.2. List of components
The list of components is used for adding visual components to the model, i.e. it duplicates
the component tabs. The component list window is available by then Tools | List of components
menu command.
Figure 3.277. List of components
3.7.3. Adding a component in visual mode
Visual adding of components requires a preliminary description of connection points for bodies, Sect. 3.6.9.6. In this mode the components can be connected with the elements already presented in the object in a very simple and intuitively clear manner. This is the advantage of visual
adding in comparison with the non-visual one.

To add a component in the visual mode
Click by the left mouse button on the component button or double click on the component
name in the component list window. The full object mode of the animation window is
switched on automatically, Sect. 3.5.1.2.2, and connection points are visualized.
Figure 3.278. Window with help comments to adding a component

Follow instructions in the help window by selecting connection points or body images.
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Figure 3.279. List of identifiers of a component

If necessary, set desired values to identifiers included in the component
To cancel the process of visual adding a component, click either the
ponent panel or the Interrupt button on the help window, Figure 3.278.
button on the com-
3.7.4. Mode of adding elements with and without autopositioning
The autopositioning function simplifies the process of visual adding elements. It is used if all
bodies of the model are in the positions satisfying kinematic constraints. As a rule this is true for
models converted from CAD assemblies. The advantages by the use of the autopositioning consist in simplification of setting a part of geometrical information to joints and force elements.
Example. By visual adding a spherical joint, two joint points should be specified in SC of a
pair of connecting bodies. If these points coincide for the current positions of the bodies in the
model, it is enough to select the joint point for the first body, and the coordinates of the second
point are computed by the program. In no autopositioning is assigned to the visual component,
both the points must be selected visually, i.e. they cannot coincide in the animation window.
3.7.5. Standard library of visual components UMComponents
3.7.5.1. List of standard components
Figure 3.280. Group of elements in the library of components
The library UMComponents includes the following elements:
• Force elements
- Bipolar linear spring
- Bipolar linear spring and damper
- Bipolar linear damper
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- Linear spring
- Linear spring with autopositioning
- Generalized linear viscous-elastic element
- Generalized linear viscous-elastic element with autopositioning
- T-force
• Joints
- Rotational joint
- Rotational joint with autopositioning
- Translational joint
- Translational joint with autopositioning
- Hook joint
- Hook joint with autopositioning
- Spherical joint
- Spherical joint with autopositioning
3.7.5.2. Visual adding generalized linear elastic or viscous-elastic forces
Here we consider in details the process of visual adding a linear force element.
The generalized linear force element is an important tool for description of springs and viscous-elastic elements. We recommend to study the mathematical model of the element before
start its usage because the model in quite not trivial, Sect. 3.6.12.5, Chapter 2, Generalized force
element.
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Figure 3.281. Systems of coordinates related to linear force elements
Description of geometric data for an elastic force element includes the following systems of
coordinates (SC, Figure 3.281):
 SC1 - local SC of body 1 with origin O1
 SC2 - local SC of body 2 with origin O2
 SCA - fixed relative to body 1, begin of the linear force element, origin at A
 SCB1 - fixed relative to body 1, end of the linear force element in unloaded state or under
the static load, origin at B1
 SCB2 - fixed relative to body 2, end of the linear force element in unloaded state or under
the static load, origin at B2
3.7.5.2.1. Automatic positioning mode
The linear spring with autopositioning
or the Linear spring + damper with autopo-
sitioning
components.
This mode is usually used for dynamic objects created as a result of data conversion from the
CAD programs.
1.
2.
Add to the first body a connection point corresponding to point A or an oriented point for
SCA (see Figure 3.281).
Add to the first body a connection point corresponding to point B1 or optionally add to the
second body a connection point corresponding to point B2 or an oriented point for SCB2
(see Figure 3.281)
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Click one of the
buttons on the component panel. The window with help comments appears. The window will include the following sequence of comments:
"Select point/oriented point at 1st body" - select by the left mouse a point for the point A or
an oriented point for SCA. If the selected point is not an oriented point, axes of SCA are set
parallel to those of SC1.
"Select element end point (first body) or point/oriented on second body".
If a point at the second body is selected, the point B2 or SCB2 is assigned. If the selected
point is not an oriented point, axes of SCB2 are set parallel to those of SC2 (the body2 - fixed
SC). Point B1 is computed automatically coinciding with B2 (see Figure 3.281) and the process
of selection geometric parameters is over. Otherwise the next step is necessary:

"Select the second body" - click by the mouse on the image of the second body. Point B2
and SCB2 are computed automatically coinciding with B1, SCB1 (Note that axis of SCB1
are parallel to SCA), see the Figure 3.281.
Figure 3.282. Identifiers parameterizing a force component
4.
Correct names and values of identifiers, parameterizing the force element (Figure 3.282)
3.7.5.2.2. The User's mode
The linear spring
or the Linear spring + damper
linear force components without automatic positioning.
1.
2.
3.
4.
components correspond to the
Add to the first body a connection point corresponding to point A or an oriented point for
SCA (see Figure 3.281).
Add to the first body a connection point corresponding to point B1
Add to the second body a connection point corresponding to point B2 or an oriented point
for SCB2 (see Figure 3.281)
Click one of the
buttons on the component panel. The window with help comments appears, the window contains instructions and comments to the element adding process:
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"Select point/oriented point at 1st body" - select by the left mouse a point for the point A or
an oriented point for SCA. If the selected point is not an oriented point, axes of SCA are set
parallel to those of SC1 (the body1 - fixed SC), see Figure 3.281.
"Select point at 1st body for element end" - select a connection point for B1 (see Figure 3.281).
"Select point/oriented point at 2nd body". On this step the point B2 or SCB2 is assigned. If
the selected point is not an oriented point, axes of SCB2 are set parallel to those of SC2 (the
body2 - fixed SC), see Figure 3.281.
Correct names and values of identifiers, parameterizing the force element
Remarks
Figure 3.283. Visualization of SC of element
1.
In the single element mode of the animation window, SCA, SCB1 and SCB2 are visualized;
the origin of SCB1 is marked by the
icon, Figure 3.283. Images of SCB1 and SCB2
should usually coincide when the geometrical data of the element are correct.
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Figure 3.284. Selection of auxiliary drawings for linear force elements
2.
In the single element mode of the animation window these systems of coordinates can be
visualized if the corresponding option is on, Figure 3.284.
3.7.6. Development of libraries of visual components
3.7.6.1. Wizard of components
Wizard of components is designed for development and editing lists of components, Figure 3.285. Use the Tools |Wizard of components… menu command or the
button to call the
wizard.
The tool panel contains
 the name of the current tab (group) of the library (UMCommon in Figure 3.285),

the button adds a new group of components of a library;

the button deletes a group of components;

the button opens a library file;

the button saves the library to a file;

the button saves the library with another name.
The Components group contains the tabs corresponding to the current group of components.
The component edit panel contains parameters of an active component:
 Name of the component, which is used as the name of the corresponding tab,
 Hint, which is used as the component name in the list of components as a hint to the component button, Figure 3.280 ,
 Path to the file with component,
 Button image for the component panel, 32x32 pixels,
 Automatic positioning key, Sect. 3.7.4,

the buttons
and
adds and removes components to the group.
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Tool panel
Component tabs
Component edit panel
Figure 3.285. Wizard of components
3.7.6.2. Image of a component button
Figure 3.286. Animation window for creating an image for a button
A special animation window can be used for creation of an image for a component button,
Figure 3.286. Use the Tools | Button go menu command to call the window. This function is
available if an active object is available in UM Input program. Use the
image into a file.
button to save the
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3.8. Saving object data
Use the File | Save as… menu command or the
button to save the active object for the
first time or to make a copy of the object (Sect. 3.4.1). Just here a name is assigned to the object.
To save a modified object use:
 the File | Save command of the main menu;
 the Ctrl+S hot key;
 the
button.
Data are stored in the input.dat file located in the object directory.
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3.9. Generation of equations of motion
Universal Mechanism supports two methods for automatic generation of equations of motion: symbolic and numeric-iterative. Let us consider them more detailed.
Before generation of equations, UM saves the modified object and verifies correctness of the
object description.
If the object description contains errors or not full, the program opens the Summary tab of
the object inspector. The summary contains a list of errors and warnings. Click a line with an error or a warning to go to the corresponding element of the object, Sect. 3.5.2.3.3.
Zero mass and moments of inertia are considered either as warnings or as errors. Use the
General tab of the UM option window (Sect. 3.3.1) to change the status.
Symbolic method assumes generation equations of motion as source files in C or Pascal
with posterior their compilation by one of the supported external compilers. As a result of compilation, the UMTask.dll appears. This library is used by UM Simulation program for numerical
integration of equations of motion.
Use the Tools | Generate equations command of the main menu to generate and (optionally)
compile equations of motion with the help of the built-in specialized computer-algebra system.
Numeric-iterative method assumes generation of equations of motion on each step of numerical integration directly in UM Simulation program. It does not requires compilation of equations with an external compiler.
Let us consider advantages and disadvantages of both methods.
In terms of CPU efforts, the symbolic method is faster. It provides decreasing CPU efforts up
to 10-100% for complex (more than 10-20 degrees of freedom) models. For rather simple models
CPU efforts for both methods are roughly the same. The symbolic method during generation of
source code fulfills its optimization from the point of view of CPU-efforts.
On the other hand the symbolic method of generation of equations of motion expects any external compiler to be installed on the same computer. Universal Mechanism supports Borland
Delphi, Borland C++ Builder, Microsoft Visual C++ as external compilers.
At the same time, the numeric-iterative method does not require explicit steps of generation
and compilation of equations of motion and seems to be simpler in usage.
For beginner users it is recommended to use the numeric-iterative method of generation of
equations of motion as simpler in usage. The symbolic method might be recommended for more
experienced users, which work with more or less complex models.
3.9.1. Numeric-iterative method
To set numeric-iterative method of generation of equations of motion select the Object item
in the tree of elements and then set Generation of equations to Numeric-iterative (see Inspector window in the right part of the constructor window).
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3.9.2. Symbolic method
To set symbolic method of generation of equations of motion select the Object item in the
tree of elements and then set Generation of equations to Symbolic (see Inspector window in the
right part of the constructor window). See Sect. 3.3.2 for setup the external compiler.
Generation and compilation of equations of motions are performed within UM Input program.
Choice of an algorithm for generation the equations allows optimizing the number of floating-point operation in the equation codes.
The group Language for output files lets you to specify the program language for output
files. You should select that language which compiler is installed on your computer.
The Compile equations checkbox presents an option for the user. If it is checked, the compilation will run right after the successful generation of equations (most often used).
If the Rewrite Control File checkbox is checked, the new version of the Control File will
replace the old one. The old Control File will be renamed as Cl[NameOfObject].old. If the box is
not checked, the new file is created as Cl[NameOfObject].new. This is important if the object
description contains external functions or/and the user write its own procedures in the Control
file.
Run simulation module if on will start UM Simulation program with automatic loading the
current model.
The Generate button starts the derivation of equations for the active object.
Use the Generate all button to derive equations for the object as well as for all external subsystems added to the object.
Use the Object | Compile equations or the Ctrt-F9 hot key to compile the equations if the
Control file has been modified but the equations have not been changed.
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3.9.3. Compilation of equations of motion
If you have chosen symbolic method of generation of equations of motion you need to compile generated equations with the help of one of supported compilers. Universal Mechanism supports using Borland Delphi, Borland C++ Builder, Microsoft Visual C++ as external compilers.
To compile equations of motion use Object/Compile equations menu item or check Compile equations flag in the Deriving and compile equations dialog, see Sect. 3.9.2.
To setup external compiler paths select Tools/Options menu item. Your further actions depend on what external compiler you are going to use:
Delphi
1.
2.
Select Paths | Delphi tab.
Click Search Delphi button.
Borland C++ Builder, Microsoft Visual C++
1.
2.
Select Paths | C++ tab.
Click one of the following buttons Search Visual C or Search Borland C++ Builder depending on which C compiler is installed on your PC.
If UM successfully detects external compiler all paths are set automatically. If not, you
should set all paths manually.
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3.10. Import data from CAD programs and formats
UM gives many tools for data import from CAD programs and formats. Three methods are
available.
1. Use of API of a CAD program. In this case, the user opens an assembly in the corresponding CAD program and uses an UM converter for transformation of the assembly into an UM
object. This approach is implemented for SolidWorks, Autodesk Inventor, ProE, Unigraphics NX, KOMPAS, see 9_UM_CAD_Interfaces.pdf file.
2. Use of an intermediate commercial viewer of CAD files CADLook for conversion of data
from STEP (both AP203 and AP214), IGES, X_T (Parasolid), SAT formats, see Chapter 9
of the user’s manual.
3. Direct reading 3ds, STL and wrl files. For instance, an assembly created in Catia v5 should
be first exported in VRML (wrl file) or STL, and then this file is read by UM if the corresponding converter is available in the current configuration of UM.
The minimal UM Base configuration includes converter of 3ds files in the UCF format,
Sect. 3.10.1, as well as reading UCF files. Other converters are included in UM configuration
according to the license agreement.
3.10.1. UCF: UM CAD format
The text format ucf (UM Cad Format) has been developed as an intermediate format by conversion of models from CAD with the help of API (Chapter 9 of the user’s manual) as well as by
direct reading 3ds, stl, vrml files.
In some of the converters the use of the ucf format is hidden, and the user gets an UM model
as a result of the import, see conversion of data from SolidWorks, Autodesk Inventor, and
KOMPAS3D. In other cases, an ucf file is the result of data conversion, and the UM model is
created after reading the file by the Tools | Import from CAD | UM CAD file menu command,
or by the
button, see Sect. 3.10.4 as an example.
3.10.2. UMD format for models imported from CAD
The UMD format of UM model is the basic format in UMLite and UM Express programs. In
UM7.0 this format is used as an auxiliary one after conversion of an assembly from CAD.
The input.umd file is created simultaneously with the standard input.dat file by the first
save of the imported model. In comparison with input.dat, the input.umd file contains additional
information about the assembly tree, including parts, their names, inertia parameters, images.
Taking into account this information, the user can automatically merge parts to bodies with automatic recomputation of the body inertia parameters and image. See Chapter 9, Sect. Model
processing after conversion for more details. As a rule, the file is not used after finishing the
model modification.
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3.10.3. Model processing after import from CAD
As a rule, a completion of the model after import from CAD is necessary. The specific model
modification include the following tools and steps:
 joining of parts into bodies, see Chapter 9, Sect. Model processing after conversion; this
operation is available is the user reads the model by the File | Open *.umd.
 sometimes evaluation of inertia parameters is necessary; it is recommended to use the UM
tool for automatic computation of inertia parameters on body image, Sect. 3.6.9.2;
 change of colors and positions;
 automatic detection of edges if the edges are not imported from CAD, i.e. in the most of
cases, Sect. 0.
3.10.4. Reading 3ds files
UM supports import of images developed in 3D Studio. The converter reads a 3ds file and
converts is to UCF format, Sect. 3.10.1.
Figure 3.287. Converter 3ds files
Consider steps of the conversion process.
1.
2.
3.
4.
Open the converter by the Tools | Import from CAD | 3ds menu command or by the
button on the tool panel, Figure 3.287.
Select a 3ds file by the
button. The model sizes are computed automatically. The sizes
include the minimal and maximal value of coordinates along each of the axes.
According to sizes data, a length unit must be selected with the drop-down list. If necessary,
a special unit factor can be assigned by the user.
A shift and rotation can be assigned to the model, if necessary.
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Save results of the conversion into an UCF file.
Read the UCF file by the Tools | Import from CAD | UM CAD file or by the
If necessary, change the unit, shift and rotation and repeat the conversion.
button.
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3.11. Import of MSC.ADAMS models
1.
2.
3.
4.
5.
To convert MSC.ADAMS models in UM format, the following steps are necessary.
Load the model in MSC.ADAMS.
Use the File | Export menu command to save the model with the File type: ADAMS/View
Command File (*.cmd).
Use the File | Export menu command to save the model with the File type: ADAMS/Solver
Data Set (*.adm). The option Write default values must be active.
File must have the same name and must be located in the same directory.
Load the UMInput program.
Open the converter window by the File | Import from MSC.ADAMS menu command,
Figure 3.288.
Figure 3.288. Converter window
6.
7.
8.
9.
Select cmd and adm files with the model by the
button.
Run the conversion process by the Convert button.
Verify the model. If some files with images are not found, add paths to the list and repeat
the process.
If the elements of the “Link” have wrong orientation after the conversion, Figure 3.289a,
check the Additional rotation for a link option and repeat the conversion, Figure 3.289b).
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b)
Figure 3.289. Additional rotation for a link
A box in the bottom of the window contains information about faults in the conversion results.






List of convertible elements:
bodies, their names, images and inertia parameters;
markers are converted into oriented connection points, Sect. 3.6.9.6.2;
joints of basic types;
main force elements (ADAMS Solver notions): bushing, sforce, springdamper, ptcv (pointcurve follower);
curves;
variables if the Convert variables option is checked, Figure 3.288.
Remark 1.
Remark 2.
There are some limitations in conversion of elements. For instance, the conversion of User functions as well as some kinematic functions and images is not
supported. Contact interaction by images is not supported. If some units are different from SI (length - meter, time - second, mass - kilogram), incorrect conversion of some expressions is possible.
Conversion of rail vehicles leads to wrong results because of ADAMS/Rail errors
by export data to ADAMS/View and ADAMS/Solver formats.
Experience in use of the model converter proves that even complex models developed in
MSC.ADAMS can be successfully transformed to UM format, Figure 3.290, Figure 3.291.
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Figure 3.290. Model of a rear truck suspension
Figure 3.291. Car model
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