/smash/get/diva2:224078/FULLTEXT01.pdf

/smash/get/diva2:224078/FULLTEXT01.pdf
Model Based Aircraft Control System
Design and Simulation
Raghu Chaitanya.M.V
Division of Machine Design
Degree Project
Department of Management and Engineering
LIU-IEI-TEK-A--09/006300--SE
II
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© Raghu Chaitanya M V
III
European Masters in Design and Technology of Advanced Vehicle
Systems (EUROMIND) – Aeronautics
Model Based Aircraft Control System
Design and Simulation
Raghu Chaitanya.M.V
LIU-IEI-TEK-A--09/006300--SE
Supervisor:
Mehdi Tarkian
PhD, Linköping University
Examiner:
Christopher Jouannet
Assistant Professor, Linköping University
IV
V
Abstract
Development of modern aircraft has become more and more expensive
and time consuming. In order to minimize the development cost, an
improvement of the conceptual design phase is needed. The desired goal
of the project is to enhance the functionality of an in house produced
framework conducted at the department of machine design, consisting of
parametric models representing a large variety of aircraft concepts.
The first part of the work consists of the construction of geometric
aircraft control surfaces such as flaps, aileron, rudder and elevator
parametrically in CATIA V5.
The second part of the work involves designing and simulating an Inverse
dynamic model in Dymola software.
An Excel interface has been developed between CATIA and Dymola.
Parameters can be varied in the interface as per user specification; these
values are sent to CATIA or Dymola and vice versa. The constructed
concept model of control surfaces has been tested for different aircraft
shapes and layout. The simulation has been done in Dymola for the
control surfaces.
VI
VII
Acknowledgement
Master thesis work is carried out in the Department of Management
and Engineering, Division of Machine Design at Linköping University
(LITH) Linköping, Sweden. As a part of acknowledgement, I want to
express my gratitude towards many people whose insightful suggestions
and contributions have enabled me to enhance my work at each stage. In
addition to this, I wish to acknowledge the assistance provided by IEI
Department of Linköping University.
I am deeply indebted to my supervisor Mehdi Tarkian from Linköping
University whose help, suggestions and encouragement during the
research process enabled me to successfully complete my master thesis.
I specially thank Prof. Patrick Berry and Christopher Jouannet for their
guidance.
Especially, I am grateful to my parents and brothers whose love and
affection has been a great support for each and every success in my
carrier. My friends are always with me encouraging during difficult
situations and played a vital role in my work.
Raghu Chaitanya.M.V
VIII
IX
CONTENTS
1. INTRODUCTION .....................................................................................................................................1
1.1 BACKGROUND .......................................................................................................................................1
1.2 OBJECTIVE .............................................................................................................................................2
1.3 CONCEPTUAL DESIGN ON AIRCRAFT CONTROL SURFACES AND ACTUATORS ........................................2
1.3.1 Control surfaces conceptual design ..............................................................................................2
1.3.2 Actuator conceptual design...........................................................................................................4
2. FLIGHT CONTROL SYSTEM ...............................................................................................................7
2.1 PRINCIPLE OF FLIGHT CONTROL ............................................................................................................7
2.1.1 Lift.................................................................................................................................................7
2.1.2 Weight ...........................................................................................................................................7
2.1.3 Drag ..............................................................................................................................................8
2.1.4 Thrust ............................................................................................................................................8
2.2 FLIGHT CONTROL SURFACES .................................................................................................................8
2.3 PRIMARY CONTROL SURFACES ..............................................................................................................9
2.3.1 Ailerons.........................................................................................................................................9
2.3.2 Elevators .....................................................................................................................................10
2.3.3 Rudder.........................................................................................................................................10
2.4 SECONDARY CONTROL SURFACES .......................................................................................................10
2.4.1 Flaps ...........................................................................................................................................11
2.4.2 Slats.............................................................................................................................................11
3. ACTUATOR THEORY ..........................................................................................................................13
3.1 INTRODUCTION ....................................................................................................................................13
3.2 CLASSIFICATION OF ACTUATORS .........................................................................................................13
3.2.1 Fluid mechanical ........................................................................................................................13
3.2.2 Electric Actuators .......................................................................................................................14
3.2.3 Electromagnetic actuator............................................................................................................14
3.2.3.1 Electrodynamic actuator...................................................................................................................... 15
3.2.3.2 Electromechanical ............................................................................................................................... 15
4. MULTIDISCIPLINARY DESIGN ........................................................................................................19
4.1 MODEL DEFINITION FOR RE-USABILITY ................................................................................................19
4.2 DEFINING REUSABLE MODEL IN CATIA..............................................................................................21
4.3 KNOWLEDGE ADVISOR.........................................................................................................................21
4.3.1 Formula Function .......................................................................................................................22
4.3.2 Rule Function..............................................................................................................................22
4.3.3 Reaction Function.......................................................................................................................22
4.3.4 Check Function ...........................................................................................................................22
4.3.5 Parameter Set Function ..............................................................................................................22
4.3.6 Relation Set Function..................................................................................................................23
4.3.7 Power Copy Instances.................................................................................................................23
4.3.7.1 Manually Initiated Power Copies ........................................................................................................ 23
X
4.3.7.2 Automatic Initiated Power Copies in a Part ........................................................................................ 24
5. GEOMETRIC MODEL..........................................................................................................................26
5.1 AIRCRAFT PARAMETRIC MODEL..........................................................................................................26
5.1.1 Use of CATIA in the Thesis .........................................................................................................26
5.2 STRUCTURE BUILDUP ..........................................................................................................................26
5.2.1 Aileron Buildup...........................................................................................................................28
5.2.2 Elevator Buildup .........................................................................................................................29
5.2.3 Rudder Buildup ...........................................................................................................................30
5.2.4 In-board and Out-board Flaps Buildup ......................................................................................30
5.3 CONSTRUCTION OF CONTROL SURFACE ...............................................................................................32
5.3.1 Construction of aileron skin........................................................................................................32
5.3.2 Construction of aileron spars......................................................................................................33
5.3.3 Construction of aileron ribs ........................................................................................................35
5.4 FLAP MECHANISM ...............................................................................................................................37
6. DYNAMIC MODEL ...............................................................................................................................39
6.1 DYMOLA ..............................................................................................................................................39
6.2 MODELICA ...........................................................................................................................................39
6.3 DYNAMIC MODEL ................................................................................................................................40
6.4 ACTUATOR CALCULATION...................................................................................................................42
6.4.1 Actuator weight estimation .........................................................................................................42
6.4.2 Torque calculations ....................................................................................................................42
7. USER INTERFACE................................................................................................................................45
7.1 CATIA USER INTERFACE ....................................................................................................................46
7.2 DYMOLA USER INTERFACE ..................................................................................................................46
8. DISCUSSION AND CONCLUSION .....................................................................................................49
9. APPENDIX ..............................................................................................................................................52
9.1 DIFFERENT AIRCRAFT CONFIGURATIONS .............................................................................................52
9.2 KNOWLEDGE ADVISOR.........................................................................................................................53
9.3 ADAPTABILITY OF THE AILERON ..........................................................................................................54
9.4 PROCEDURE FOR MODIFICATION OF THE MECHANISM ..........................................................................55
9.5 DYNAMIC SIMULATION MODEL ............................................................................................................57
9.6 VISUAL BASIC CODE FOR AUTOMATIC INSTANTIATION OF THE RIBS ....................................................57
9.6.1 Deleting Instantiate of ribs .........................................................................................................57
9.6.2 Instantiation of ribs.....................................................................................................................58
9.7 TORQUE CALCULATIONS IN DYMOLA ..................................................................................................59
10. REFERENCES ......................................................................................................................................62
1
1. INTRODUCTION
1.1 Background
Systems engineering is a technique which is used in many engineering
fields such as control engineering, industrial engineering, and interface
design etc to deal with the complex projects. Coordination between
projects and teams can be handled. The used tools are modeling,
simulation, analysis and scheduling. Apart from this overlapping
between technical and human disciplines can be managed with system
engineering [7, 30].
A design phase consists of many compromises such as technical and
economical factors. New methods that allow engineers to achieve a
design at low cost and time have to be developed. In the aircraft industry
the recent challenge is to improve design, lower production time and
cost. Figure 1.1 [15] shows an interdisciplinary for Aircraft Conceptual
Design.
Figure 1.1: Interdisciplinary for Aircraft Conceptual Design
2
1.2 Objective
The purpose is to increase the functionality of the Conceptual Aircraft
Design by the construction of control surfaces on an existing Conceptual
Aircraft Design and to integrate two powerful tools that are being used in
the design and analysis processes in aircraft Industry. The
interdisciplinary covered in this project is as shown in Figure1.2 [15].
Figure 1.2 : Interdisciplinary in this project
The objectives of the thesis are
1. Construction of structure control surfaces such as flaps, aileron,
rudder and elevator using CATIA V5.
2. Simulation of the dynamics of the control surfaces in Dymola.
3. Extend several functionalities in the Excel User-Interface.
1.3 Conceptual Design on Aircraft Control surfaces and
Actuators
1.3.1 Control surfaces conceptual design
The primary control surfaces are ailerons, elevator and rudder, while the
secondary control surfaces are flaps and slats. The required aileron area
can be estimated from Figure 1.3 [6]. The ailerons extend from 50% to
90% of the span and remaining extra 10% provides little control
3
effectiveness due to the vortex flow at the wing tips. In some cases, the
ailerons extend until the wing tips.
Figure 1.3: Aileron guidelines
Elevators and rudders generally start on the side of the fuselage and
extend to the tip of the tail [90% of the tail span].In case of High-speed
aircraft; a rudder of large chord extends to about 50% of the span and
avoids a “rudder effectiveness” problem which is similar to “aileron
reversal”. For maximum lift flaps the span must be as large as possible;
they occupy the part of the wing span, inboard of the ailerons.
In order to maintain a constant percent chord, the control surfaces are
tapered in chord by the equivalent ratio as wing or tail which is shown in
Figure 1.4[6]. In general, flaps and aileron are 15% to 25% of wing chord,
while elevator and rudder are of 25% to 50% of the tail chord.
In case of control surfaces, the hinge axis should not be farther aft than
20% of the average chord as shown in Figure 1.5[6]. In a manuallycontrolled aircraft, the horizontal tail is designed in such a way that it is
always normal to the aircraft central line. This helps in connecting righthand and left-hand elevator surfaces to the torque tube [6, 9, 10, 21]. For
the construction of control surfaces in section 5 this knowledge is
implemented. The user can take into account the information to design
and modify accordingly.
4
Figure1.4: Chord control surface for constant-percent
Figure1.5: Aerodynamic balance
1.3.2 Actuator conceptual design
The actuator sizing method depends upon the actual basic design and
varies depending on manufacturer. The functionality of the actuator is to
sustain the operating thrust, pressure in the process. In engineering
applications, the electromechanical or electrohydraulic actuators are
sized upon the process as well as frictional forces that appear with added
thrust to maintain the safety conditions.
With the high level of engineering required for these actuators, the
prevailing thought is that it is better have too much actuator than not
enough. The safety factor for sizing varies from 25% to 50% of the
5
actuator available thrust. The cost of the electromechanical and
electrohydraulic actuators is considerably high.
In cases of higher performance and speed, electromechanical and
electropneumatic actuators are recommended instead of pneumatic or
hydraulic actuators. The electromechanical and electrohydraulic
actuators are used in special or severe based on flow rate and pressure
drop .Only a brief introduction for the actuator design is provided here,
for detailed designs of actuators see the references [11, 12, 21, 22].
6
7
2. FLIGHT CONTROL SYSTEM
2.1 Principle of Flight Control
The four basic forces acting upon an aircraft during flight are lift, weight,
drag and thrust as shown in Figure 2.1.
LIFT
THRUST
DRAG
WEIGHT
Figure 2.1: Forces acting on an aircraft
2.1.1 Lift
Lift is caused by the flow around the aircraft. Lift is the upward force
created by the wings, which sustains the airplane in flight. The force
required to lift the plane through a stream of air depends upon the wing
profile. When the lift is greater than the weight then the plane raises.
2.1.2 Weight
Weight is the downward force created by the weight of the airplane and
its load; it is directly proportional to lift. If the weight is greater than lift
then the plane descends.
8
2.1.3 Drag
“The resistance of the airplane to forward motion directly opposed to
thrust”. The drag of the air makes it hard for the plane to move quickly.
Another name for drag is air resistance. It is created or caused by all the
parts.
2.1.4 Thrust
The force exerted by the engine which pushes air backward with the
object of causing a reaction, or thrust, of the airplane in the forward
direction.
2.2 Flight Control Surfaces
An aircraft requires control surfaces to fly and move in different
directions. They make it possible for the aircraft to roll, pitch and yaw.
Figure 2.2 [8] shows the three sets of control surfaces and the axes
along which they tilt.
Pitch axis
Yaw axis
Elevator
Aileron
Flap
Rudder
Elevator
Flap
Aileron
Roll axis
Control
Rudder
column
pedals
Fig ur e 2 . 2 (a )
ROLLING
PITCHING
YAWING
Control column
turned
Control column
moved forward
Rudder pedals
turned
Fig ur e 2 . 2 (b )
Fig ur e 2 . 2 ( c )
Fig ur e 2 . 2 (d )
NORMAL TURN
Control column
and rudder pedals
turned
Fig ur e 2 . 2 ( e )
Figure 2.2: Control Surfaces and Axes
There are three sets of control surfaces that tilt the plane along three
axes. The ailerons, operated by turning the control column [Figure
2.2(a)], cause it to roll. The elevators are operated by moving the control
column [Figure 2.2(a)] forward or back causes the aircraft to pitch. The
rudder is operated by rudder pedals that make the aircraft yaw.
9
Depending on the kind of aircraft, the requirements for flight control
surfaces vary greatly, as specific roles, ranges and needed agilities.
Primary control surfaces are incorporated into the wings and empennage
for almost every kind of aircraft as shown in the Figure 2.3 [1]. Those
surfaces are typically: the elevators included on the horizontal tail to
control pitch; the rudder on the vertical tail for yaw control; and the
ailerons outboard on the wings to control roll. These surfaces are
continuously checked to maintain safe vehicle control and they are
normally trailing edge types.
Figure 2.3: Flight Control Surfaces of Jet Passenger Carrier
2.3 Primary Control Surfaces
The primary flight controls surfaces are ailerons, elevator and rudder.
2.3.1 Ailerons
Movement about the longitudinal axis is controlled by the two ailerons,
which are movable surfaces at the outer trailing edge of each wing. The
movement is roll. If the aileron on one wing is lowered, the aileron on the
other will be raised. The wing with the raised aileron goes down because
of its decreased lift and the wing with the lowered aileron goes up
because of its increased lift. Thus, the effect of moving one of the ailerons
is complemented by the simultaneous and opposite movement of the
aileron on the other wing.
The ailerons are connected to each other and to the control wheel (or
stick) in the cockpit by rods or cables. While applying pressure to the
right on the control wheel, the right aileron goes up and the left aileron
goes down. Thus, the airplane is rolled to the right as the down
movement of the left aileron increases the wing camber (curvature) and
10
the angle of attack. The right aileron moves upward and decreases the
camber, what results in a decreased angle of attack. Thus, an increased
lift on the left wing and decreased lift on the right wing cause a roll and
bank to the right.
2.3.2 Elevators
The movement of the airplane about its lateral axis is controlled by the
elevators. This motion is called pitch. The elevators are free to swing up
and down and form the rear part of the horizontal tail assembly. They are
hinged to a fixed surface; the horizontal stabilizer. A single airfoil is
formed by the horizontal stabilizer and the elevators. The chamber of the
airfoil can be modified by changing the position of the elevators, which
increases or decreases the lift.
Control cables are used to connect the elevators to the control wheel (or
stick) as it happens with the ailerons. The elevators move downward
when forward pressure is applied on the wheel. Thus, the lift produced
by the horizontal tail surfaces is increased, what forces the tail upward,
causing the nose to drop. Conversely, the elevators move upward, when
back pressure is applied on the wheel, decreasing the lift produced by
the horizontal tail surfaces, or maybe even producing a downward force.
The nose is forced upward and the tail is forced down.
The angle of attack of the wings is controlled by the elevators. When back
pressure is applied on the control wheel, the angle of attack increases as
the tail lowers and the nose rises. Conversely, the tail raises and the nose
lowers when forward pressure is applied, decreasing the angle of attack.
2.3.3 Rudder
The movement of the airplane about its vertical axis is controlled by the
rudder. This motion is called yaw. The rudder is a movable surface
hinged to a fixed surface which is the vertical stabilizer, or fin. Its action
is similar to the one of the elevators, except that it swings in a different
plane; from side to side instead of up and down. The rudder is connected
to the rudder pedals by controlled cables.
2.4 Secondary Control Surfaces
Wing Leading and Trailing edges are used to increase the aerodynamic
performance of the aircraft by reducing stall speed mainly during take-off
and landing speed. High lift control is provided by a combination of flaps
and leading edge slats. The flap control is affected by several flap
sections located on the inboard two-thirds of the wing trailing edges. The
flaps are deployed during take-off or the landing approach to increase the
wing camber and improve the aerodynamic characteristics of the wing.
11
2.4.1 Flaps
Flaps are mounted on the trailing edge but can also be mounted on the
leading edge. They extend the edge by increasing the chord of the wing.
They pivot only (simple and split flaps), extend and come down (complex
and slotted flaps) or extend and camber (Krueger flaps). There are other
types as well.
2.4.2 Slats
Slats are usually mounted on the leading edge. Slats extend the edge and
they sit like a glove on the edge. "Slats" is an abbreviation for "slotted
flaps", which means they have a nozzle like slot between the high-lift
device and the wing; on the contrary, flaps do not have this slot. Figure
2.4 [4] shows the wing leading and trailing edge configurations commonly
used.
Figure 2.4: Wing Leading and Trailing edge Configurations
12
13
3. ACTUATOR THEORY
3.1 Introduction
Actuators are the devices that convert energy into motion; the motion
can be either linear or rotary motion. Actuators act as the final elements
in a control system. An energy input and a low power command signal
are sent to the actuators to be amplified as appropriate to produce the
required output. There is a wide range of applications that vary from
simple low power switches to high power hydraulic devices operating
flaps and control surfaces.
3.2 Classification of Actuators
Actuators are broadly classified into two kinds, one is fluid mechanical
and another one is electric.
3.2.1 Fluid mechanical
Fluid mechanical actuator drives are in the form of hydrostatic energy
converters. In most of the applications their operation is based on the
displacement principle, so they convert the pressure energy of the fluid
into mechanical work and vice-versa. Fluid mechanical actuator mainly
consists of piston, cylinder and springs. Piston is operated inside the
cylinder filled with fluids and works against spring force. The rectilinear
motion is transmitted from the piston to other actuating elements for the
desired motion. Automotive brakes are an important example.
The two types of fluid mechanical actuators are Pneumatic and Hydraulic
Actuators, the common device is a pneumatic cylinder and hydraulic
cylinder respectively. The hydrodynamic transformer converts flow
energy (kinetic energy of the moving fluid) into mechanical work. The
hydrodynamic torque converter used in most automatic transmission
systems is an important automotive application. Figure 3.1(a) [26] shows
hydraulic actuator and Figure 3.1(b) [26] shows pneumatic actuator that
is used in aircrafts.
14
Figure 3 . 1 (a ) Hydraulic Ac t ua t or
Fig ure 3 . 1 ( c ) Ele c trom ag n e t i c
Act ua t or
Figure 3 . 1 (e ) Ele c tro hy dro s ta ti c
(EHA) Ac t ua t or
Figure 3 . 1 (b ) Pn e u ma t i c Ac t ua t or
Figure 3 . 1 (d ) Ele c tro h ydrauli c (EH)
Act ua t or
Figure 3 . 1 (f ) Ele c tro m e c ha ni cal (EM)
Act ua t or
Figure 3.1: Different types of Actuators used in Aircrafts
3.2.2 Electric Actuators
Electric actuators are operated by motor drive which provides input to
valves. The most common types of valves used in electric actuators are
gate valves. Some of the types of electric actuators are electromagnetic,
electrodynamic and electromechanical.
3.2.3 Electromagnetic actuator
They use the mutual attraction of soft ferrous materials in a magnetic
field. One coil has the function of providing the field energy to be
transformed. A return device, as a spring, is needed because the
15
attractive force is unidirectional. The fans, head lights, horn and wipers
in cars, are switched on with a current demand that is supplied by relays
or solenoids based on this principle. Figure 3.1 (c) [26] shows an
electromagnetic actuator.
3.2.3.1 Electrodynamic actuator
It is based on the (Lorenz) force generated when a current carrying
conductor is placed in a magnetic field. DC motors are frequently used as
part of an actuator system. Actuating elements are activated by very
strong magnetic field and it is possible to operate mechanisms such as
circuit breaker, hammer etc. As per the mechanism, current induces
transient magnetic field in the conductor which produces repulsive forces
between the coil and the conductor and enables to activate the actuator.
In order to minimize the wear and tear of repulsive elements, the system
is connected to coolants. For an effective work of the system, recoil forces
are damped properly. Figure 3.1(e) [27] shows an electrodynamic
actuator.
3.2.3.2 Electromechanical
The two renowned concepts such as Electro-Hydrostatic Actuators (EHA)
and Electro-Mechanical Actuators (EMA) come under the broader domain
of more electric aircraft (MEA).The electrical-power have been used more
frequently and successfully with the concept More Electric Aircraft
(MEA). The need of MEA concept is to run not only the high power
electric actuation systems but also the flight control surfaces such as
rudders, ailerons and spoilers. Figure 3.1(f) [27] shows an
electromechanical actuator.
Hydraulic systems are being replaced with electrical devices. This trend
is due to the desire of having cleaner systems (no hydraulic fluid) and
making the integration with other (normally electrical) control systems
easier to achieve. Hydraulic system was the only system available until
recently but new cars are often fitted with electric power assisted steering
now. Braking systems development is also progressing in the field of
electrical assistance. In the aviation industry, it is also possible to
observe these trends of electrical systems, but there are some difficulties
due to the very high power densities and forces required from some
actuators.
In this concept, the basic idea is to replace hydraulics with the electrical
systems which not only increases the efficiency but also provides less
maintenance cost [14]. The major objective is to provide detailed
information regarding suitability and safety with respect to actuators
that are in turn operated by electrical motors and power converters.
Broadly actuators are classified into two groups: Electro Hydrostatic
16
Actuator (EHA) and Electro-Mechanical Actuator (EMA). EHA concept
have been used in aircraft such as Airbus A380 and Boeing 787 because
of its level of safety, low production cost and emission standards. Apart
from these characteristics, it is jamming free under working
environment. Even though EHA technology has been successfully used in
new aircrafts such as A380 and Boeing 787, its initial and maintenance
cost is much higher when compared to EMA [14], it makes EMA concept
advantageous.
EMA is a concept of loading an actuator on demand but in case of EHA,
the hydraulic actuators needed to be loaded continuously independently
of the operation. The basic components used in EMA concept electrical
machine are a gear box and screw mechanism. Even though there are
numerous advantages, safety and reliable factors such as jamming free
are needed in EMA. The additional use of equipments can improve the
safety and reliability raising the cost and complexity. EMA has been used
successfully in the secondary flight controls and military aircrafts.
Figure 3.2: Direct Drive architecture for EMA
Direct Drive architecture for EMAs has also been used successfully in
train and launcher applications by overall dimensions and weight
optimization. This technology has merits in compactness and weight
optimization. The direct drive electrical system is described on basis of
Figure 3.2 [14]. It is built by a power convertor and an electrical motor.
17
The electrical motor is connected to a roller screw and the screw is
connected to the actuator.
Linear Variable differential Transducer (LVDT) converts the rectilinear
motion of an actuator to electrical signal for the purpose of control. The
power converter is used to regulate the angular velocity of the electric
motor and torque output with respect to voltages applied in stator
windings. The sub components in power converters are a rectifier, filter,
dc link capacitor and inverter. The inverter is recommended to be
connected with dc link by means of a capacitor for constant voltage.
High frequency power transistors are needed for the conversion of D.C
voltage into A.C voltage.
The safety and reliability are the key objectives in aircraft industry which
is based on motor and electronics. The motor and electronics are
internally dependent on inverter characteristics, such as:
• High efficiency in the full operating range
• High torque per ampere design which leads to reduction of losses
and height
In this work a simple EMA is considered. Due to its simplicity and
construction as shown in section 5, having a model of this nature is
more beneficial. The transmission of motion in this designed EMA is
linear.
18
19
4. MULTIDISCIPLINARY DESIGN
4.1 Model definition for re-usability
CAD tools are used for design and found application in conceptual design
generating output such as weight, mass inertia and centre of gravity etc.
For analysis, traditional tools were ineffective and giving poor results. By
innovative ways of CAD modeling, an effective geometrical model that
includes several concepts is developed. Geometrical modeling is
categorized into two; one that explained morphological levels of geometry
and another that explains the effectiveness, reusability of various
geometrical objects.
b
Script
Based
Relation
if shape = ”sq”
h { h = 10, b = h }
else { h = 10,
b = 2*h }
b
Mathematic Based
Relation
h
h = 10
b = 2*h
b
Parameterization
h = 10
h b = 20
Fixed Object
Figure4.1 the morphological pyramid visualizing the stages of geometric modeling
Morphologic geometric objects are categorized into four stages:
•
Fixed Objects (FO) are geometrical objects with fixed shape. These
objects are either intentionally or non-intentionally, static and
have fixed output.
•
Parameterization is the model in which geometric object values and
their outputs are varied. There exists no relation between
geometric object and are unrealistic.
20
•
To minimize the input parameters, a relation between objects of
the model is needed and can be done by Mathematic based relation
(MBR) in Figure 4.1.
•
Script Based Relations (SBR) models were generated by the
relations using script based programming which was described in
Figure 4.1. The main advantage SBR over MBR is the existence of
non numerical parameters.
The relations in stage 3 & 4, are explained not only by direct script in
CAD software, but also connected externally via the CAD API (application
programming interface).The demerits of morphological based models in
the automatic design application process are that the numerous objects
are fixed during the simulation. More over, a method to make the models
efficient, reusable and/or replaceable is still yet to be developed.
In order to explain the topological process two terms namely template
and constraint are used. “A template refers to an initial model to be reinitiated and constraints are conditions which have to be satisfied by the
initiated instances”. The various levels of initiating geometric instances
are visualized in the topological pyramid in Figure 4.2.
Figure 4.2 topological pyramid visualizing the stages of geometric initialization
The topological pyramid consists of the following stages:
•
Automatic Initialization (AI): Template is defined and the constraint
is undefined in the first stage of the designing process. Models are
generated and degenerated by CAD tools such as pattern. Some
cases models a lack unique parameters and it cannot be context
dependent due unconstraint model definition.
21
•
Context dependency for initiated instances is obtained by template
and constraint production. The template initiation in stage 1 leads
to reusability in stage 2 (Generic Initialization (GI)).
•
Generic Automatic Initialization (GAI) is used when there is a need
of pre-defined functions which generate or delete instances
depending upon user input.
4.2 Defining Reusable model in CATIA
The programming languages such as Visual Basic for Applications (VBA),
and the Engineering Knowledge Language (EKL) are supported by
CATIAV5. A compilation is done before execution improving the
performance of the system. Figure 4.3 shows the programming language
with respect to execution speed, accessibility and control. The portion
which was completed is plotted on y-axis and fastness of code on X-axis.
In the engineering Knowledge Language (EKL) name, their names and
addresses are explicitly written while in VBA the name is variable.
Figure 4.3: Performance difference between EKL, VBA and CAAV5
4.3 Knowledge advisor
The workbench of the Knowledge Advisor is visualized in Figure 9.4 in
Appendix. The following section explains the important functions and
tree important objects that have been used during the work.
22
4.3.1 Formula Function
This function is used to create and modify the parameters as shown
Figure 4.4(a) in Appendix. To create a new parameter, the type of
parameter is selected first and then a value or a formula is added to it.
Newly created parameter can be seen in the Parameter tree; the object
Parameters such as Curve, Circle, Point and Line which are featured
under a Geometric Set as Object Parameter. If a relation or rule is not
specified all the newly parameters in the formula function are called a
parameter. A Relation based Parameter is called a Derived Variable, and
Parameter is called Derived Object Variable.
4.3.2 Rule Function
Rule was formed with the help of Engineering Knowledge
which was shown in Figure 4.4 (b). The script was written in
window and software was provided by basic scripts to help
Parameters were created as per requirement in the tress
controlled by the rules.
Language
the editor
the user.
and were
4.3.3 Reaction Function
Here a Reaction is created using the Engineering Knowledge Language or
Visual Basic Language of CATIA. The Reaction created is visualized
under a Relation Set in the models tree. The reaction is a feature that
reacts to events on its sources by triggering an action. It is designed to
cope with the rules and the behaviors limitations and to create more
associative and reactive design.
The script is written in the editor window. A Dictionary is incorporated to
assist the user with basic scripts just as the Rule function. However if
the VB action is chosen then another editor environment will be shown
and the script is written following the VB syntax instead of EKL.
4.3.4 Check Function
Check is created using the Engineering Knowledge Language of CATIA.
The Check created is visualized under a Relation Set in the models tree.
A Dictionary is incorporated to assist the user with basic scripts just as
the Rule function.
4.3.5 Parameter Set Function
By clicking on the Parameter Set Function a Parameter Set is created in
which a set of Parameters can be stored in the model tree. An example of
how such a division might look like is visualized in Figure 4.8.
23
4.3.6 Relation Set Function
By clicking on the Relation Set Function a Relation Set is created in
which a set of Relations can be stored in the model tree.
Type of Parameter
No. of Values
Figure 4.4 (a) Formula function
Figure 4.4 (c) Reaction function script editor
Figure 4.4 (b) Rule function script editor
Figure 4.4 (d) Parameters ordered in a
hierarchal fashion using Parameter Sets
Figure 4.4: Knowledge advisor functions
4.3.7 Power Copy Instances
By means of Power Copy function a template is produced which is
initiated either manually or automatically and reused in the topological
pyramid.
4.3.7.1 Manually Initiated Power Copies
The Generic Initialization level of the topological pyramid is generated
manually with the help of power copy function in CATIA. The two
scenarios to reach this level for the created templates are:
•
A need of context reliant while defining restrictive boundary
conditions.
24
•
In the context the geometric objects of the initiated instances
should be modified parametrically. Every geometric objects defined
in the model have unique parametric values.
In order to achieve the GI method in CATIA, the power copy function is
helpful, where the Template model, visualized under Selected
Components, consists of a point, a sketch, a relation and a parameter. In
Inputs Components the required Constraint is shown and the sketch is
constructed on the plane. In order to have boundary conditions two
spline curves are constructed in the sketch.
4.3.7.2 Automatic Initiated Power Copies in a Part
In this section an example is shown in how the ribs of the flap of Aircraft
model are generated. The model tree of the ribs part can be seen in
Figure 5.15. Here a power copy is initiated automatically, but also the
reduction process of the instances is performed by introducing a new
reaction, in this case called Initiate_delete_Sets. Refer Appendix for the
code used to create the ribs.
25
26
5. GEOMETRIC MODEL
5.1 Aircraft Parametric Model
5.1.1 Use of CATIA in the Thesis
The existing parametric aircraft model has been designed in CATIA and
this work involves designing the control surfaces for it.
The basic workbenches used in CATIA are:
1. Knowledge Advisor
2. Generative Shape Design
3. Part Design
4. Assembly Design
All the control surfaces; elevator, aileron, rudder and flaps, have been
designed parametrically using CATIA. The way of designing the control
surfaces is explained in detail in 5.2
5.2 Structure Buildup
The Parametric Model of the control surfaces has been built to export the
geometry to CATIA by means of Excel user interface. The model has been
built and re-built several times to accomplish the goals. It has been a
challenge to find the simplest functioning model.
Every part has a set of parameters that are controlled by Rules and
Reactions. The user needs to change the parameters in the model to get
the desired result. The structure hierarchy is as shown in Figure 5.1. The
Control surfaces designed are as shown in Figure 5.2
27
Figure 5.1: Aircraft Structure Build Up
IN-BOARD
FLAP
RUDDER
OUT-BOARD
FLAP
ELEVATOR
AILERON
Figure 5.2: Aircraft structure
28
5.2.1 Aileron Buildup
Figure 5.3: Parts in aileron assembly
Figure 5.3 shows the parts that are present in the aileron assembly; they
are Aileron_Ribs, Aileron_Skin and Aileron_Spars. Figure 5.4 also shows
the corresponding parameters that are available in each part.
WING
DIST FROM MIDDLE CHORD
WIDTH OF AILERON LEFT EDGE
WIDTH OF AILERON RIGHT EDGE
LENGTH OF AILERON
Figure 5.4: Aileron Structure
29
As the wing is divided into two segments, for simplicity the reference for
the aileron is taken from middle chord. The distance from the middle
chord is the ratio measured along the trailing edge. The leading edge is
created from the width of the left and right edges measured from the
trailing edge along the Middle and Tip chords respectively. The number of
ribs used in the aileron can be varied using the Excel user interface. The
Front and Rear spars thickness can also be varied as per the
requirements.
5.2.2 Elevator Buildup
The hierarchy in the elevator assembly is analogous to as shown in
Figure 5.3. The Root chord is taken as the reference to place the elevator.
The widths of the left and right edges are the ratios measured on the
Root and Tip chords respectively. The construction of the elevator is as
shown in Figure 5.5. The pictures of different aircraft configurations are
shown in Appendix.
HORIZONTAL TAIL
DIST FROM ROOT CHORD
WIDTH OF ELEVATOR LEFT EDGE
WIDTH OF ELEVATOR RIGHT EDGE
LENGTH OF ELEVATOR
Elevator with twice
the number of ribs
Figure 5.5: Elevator Structure
30
5.2.3 Rudder Buildup
The order of the rudder assembly is as that of the aileron assembly. The
Root chord is taken as the reference to place the rudder. The rudder can
only move between rear spar of the vertical tail and the trailing edge. The
construction of elevator is as shown in Figure 5.6. The pictures of
different configurations are shown in the appendix.
WIDTH OF RUDDER TOP EDGE
VERTICAL TAIL
LENGTH OF RUDDER
DIST FROM ROOT CHORD
WIDTH OF RUDDER BOTTOM EDGE
Figure 5.6: Rudder Structure
5.2.4 In-board and Out-board Flaps Buildup
The construction of both In-board and Out-board flaps is comparable.
The difference between them is only the reference taken for the
placement of the flaps. The Root chord is taken as the reference for
inboard flap and Middle chord is taken as the reference for the outboard
flap as shown in Figure 5.7.
The angle between the Rear spar of the wing and the leading edge of the
flap is given as Leading edge angle for the flap. The angle can be varied to
obtain the desired position of the flap. Root and tip chords can be
changed using the user interface.
The mechanism is also designed for the flap to extend and retract by
changing the stroke of the actuator. Many experiments are done to
design the simplest mechanism parametrically. Some examples are
shown in appendix. The actuator can also be designed using the user
interface.
31
LEADING EDGE
ANGLE FOR INBOARD FLAP
LEADING EDGE
ANGLE FOR OUTBOARD FLAP
DIST. FROM ROOT CHORD
DIST. FROM MIDDLE CHORD
IN-BOARD FLAP
OUT-BOARD FLAP
Figure 5.7: In-board and Out-board flaps Structure
ACTUATOR
LEADING EGDE ANGLE
LENGTH OF FLAP
CHORD OF FLAP LEFT EDGE
Figure 5.8: Flap Structure
CHORD OF FLAP RIGHT EDGE
32
5.3 Construction of Control surface
In this section a brief description is provided on the construction of the
aileron. The construction of other control surfaces is similar, except the
fact that only the references change. The adaptation of the aileron is
shown in Appendix.
5.3.1 Construction of aileron skin
•
Middle chord, tip chord and the trailing edge of the wing are taken
as references to construct the aileron. Two points Pt1 and Pt2 are
then created on both tips of the trailing edge as shown in Figure
5.9
•
Taking these points as the references, points Pt3 and Pt4 are
created on middle chord and tip chord with ratios equal to
‘Width_of_Alieron_Left_Edge’ and ‘Width_of_Alieron_Right_Edge’
using the ratio on curve. Line (L1) is then created by joining points
Pt3 and Pt4; it is used as the leading edge reference for the aileron.
•
Taking Pt1 as reference Pt5 is created on the trailing edge with the
ratio equal to ‘Dist_from_Middle_Chord’. Point Pt6 is then created
using the reference Pt5 with ratio equal to ‘Length_of_Alieron’.
•
Two lines L2 and L3 are drawn using these points (Pt5 and Pt6)
and parallel to the chord line. Points Pt7 and Pt8 are created by
the intersection of lines L1, L2 and L1, L3. By joining the points
Pt5, Pt6, Pt7 and Pt8 the area of the aileron is obtained.
•
Lines connecting the above mentioned points are joined to make an
extrusion. This extrusion is then split with respect to the skin of
the wing to obtain the profile for the aileron. It is then extruded
inwards to obtain the thickness for the skin as shown in Figure
5.10.
33
Middle chord
L2
L3
Pt 3
L1
Pt 7
Tip chord
L7
Pt 8
Pt 4
L4
L6
Pt 2
Pt 1
L5
Pt 5
Pt 6
Traing Edge
Figure 5.9: Aileron Construction
Figure 5.10: Aileron Skin
5.3.2 Construction of aileron spars
Front and rear spars are constructed by using the points created in the
aileron skin as references.
•
To build the front spar; points Pt9 and Pt10
points Pt7 and Pt8 respectively using the ratio
thickness. Line L8 is created by joining the
created. This line is then extruded to intersect
skin.
are created from
equal to the skin
points previously
the aileron inner
34
•
Points Pt11 and Pt12 are created by using the reference points Pt9
and Pt10 and ratio of thickness of the spar. The newly created
points are joined by line L9 and extruded to meet the inner skin.
The extrapolated surfaces are trimmed and then ‘Close surface’
option is used to obtain the solid as shown in Figure 5.12.
•
Steps 1 and 2 are repeated by taking points Pt5 and Pt6 as
reference to obtain the rear spar as shown in Figure 5.11
Pt 7
Pt 9
L7
Pt 8
L8
Front Spar
Pt 10
Pt 11
Pt 12
L 10
L4
L6
L 11
Pt 14
Pt 15
Rear Spar
Pt 13
Pt 13
L9
Pt 5
Pt 6
L5
Figure 5.11: Ribs Construction
Front Spar
Rear Spar
Figure 5.12: Aileron spars
35
5.3.3 Construction of aileron ribs
The first rib is constructed and then a ‘Power copy’ (Refer section 4) is
used to instantiate the rib.
•
For the construction of the ribs the reference points Pt11 and Pt14
are taken as reference. Points Pt15 and Pt16 are created with the
ratio equal to the rib thickness on the lines L10 and L11. Line L12
is obtained by joining the newly created points as shown in Figure
5.13.
•
The lines L4 and L12 are extruded to intersect the inner skin
surface. Later they are split with respect to the inner skin and
‘Close surface’ is used to obtain a solid.
•
All the elements used to create the rib and the rib is then used to
‘Power copy’. This is as seen in stage 3 as Generic Automatic
Initiation (Figure 4.2). Refer section 9.5 in Appendix for the code
used to instantiate the rib. The parameters used to create are as
shown in Figure 5.14, and an example is shown in Figure 5.14
Pt 16
Pt 11
Front Spar
L 10
Rib 2
Pt 12
Rib 1
Rib 3
L4
L 12
L6
L 11
Pt 14
Pt 15
Pt 17
Rear Spar
Figure 5.13: Aileron Ribs
36
Rib 1
Rib 2
Rib 3
Front Spar
Rear Spar
Figure 5.14: Aileron Ribs with parameters
Figure 5.15: Model tree of rib for the flap
37
5.4 Flap Mechanism
‘Single slotted fowler flap’ [Figure 2.4(c)] mechanism is built both for Inboard and Out-board flaps (Refer section 2 for types of flaps). The flap
extends and retracts when the stroke of the piston is changed. Wing area
and chord increases as the flap extends [Figure 5.16] and decreases as
the flap retracts. Figure 5.15 shows the extended and retracted flaps.
Figure 5.16: Retracted and extended flaps
The flap mechanism constructed is as shown in figure 5.16. The actuator
is fixed to the rear spar of the wing. Flap is connected to the piston and
as the piston extends, the flap moves to the rear. The link connecting
guide and flap helps the later to rotate. The mechanism can be modified
to suit with the different aircraft models given in Appendix.
Link connecting flap and Guide
Guide for rotation
Rear Spar
Actuator
Flap
Figure 5.17: Flap mechanism construction
Guide for translation
38
39
6. DYNAMIC MODEL
In this chapter the main point is the understanding of how the dynamic
model is built in Dymola and how the model is analyzed. The parameters
and results that have been regarded as the more relevant are the ones
that are going to be explained through this chapter.
6.1 Dymola
Dymola [25] (an abbreviation for “Dynamic Modeling Laboratory”) is a
software suitable for modeling of several kinds of physical systems. It
supports hierarchical model composition, libraries of truly reusable
components, connectors and composition of casual connections. Model
libraries are available in many engineering domains. Dymola uses a new
modeling methodology based on object orientation and equations. The
usual need for manual conversion of equations to a block diagram is
removed by the use of automatic formula manipulation [3].
6.2 Modelica
The programming language Modelica [25] is a modeling software which is
used for dynamic mathematical models. Model integration, model
evolution and reusability are the major features of Modelica [3]. Modelica
is developed by the Modelica Association and is used in both industry
and academia. The modeling and simulation supported by object
oriented structure are used in several engineering domains. Model
integration and model evolution can be managed throughout the design
process by the object oriented code. Modelica is primary based on
equations while traditional languages such as FORTRAN, C and MATLAB
were based on allocation of variables.
In order to manage complexity and integration of components and submodels connectors are used to define the interfaces between the
components. The secondary feature hierarchical modeling deals with
40
complexity of the model in which the complex model is subdivided into
few components and can be used simultaneously by many people. The
inheritance feature in Modelica is used in model evolution. Inheritance is
extremely useful from initial development and later it is used and
extended in various models for more functions. The reusability of models
is supported by classes and instances which are reused in several
models. By the application of the object oriented program it is not
possible to model them but simulate the models. [19].
6.3 Dynamic Model
The inverse dynamic model of the aircraft is developed in Dymola using
Modelica language. The model includes aircraft control surfaces that are
discussed in section 5. The dynamic model is based on the Modelica
multi-body library [20]. The connection diagram in Figure 6.1 shows an
example of an aircraft dynamic model, including the control surfaces.
An Excel interface is used for transferring parameters from the
geometrical model to the dynamic model. This provides the dynamic
model with a variable geometry with parameters such as weight, inertia,
center of gravity, etc. shown in Figure 6.1.
Figure 6.1: Parametric connection between aircraft of the geometric and dynamic
models.
41
The components used in the aircraft are as shown in Figure 6.2. The
dynamic model consists of World, representing a global coordinate
system fixed in ground. Rigid bodies with mass and inertia tensor and
two frame connectors are used to connect together. The Rigid bodies
represent individual sections as in the aircraft. The Dymola model
produces a 3D visualization of the geometric object trajectories of the
control surfaces. The components used in the control surfaces are as
shown in Figure 6.3. The simulated model is as shown in Figure 9.13.
Figure 6.2: Components of dynamic model
Figure 6.3(a) Componets used in
Figure 6.3(a) Componets used in
Aileron, Elevator and Rudder
In-board and Out-board Flaps
Figure 6.3: components used in control surfaces
42
6.4 Actuator Calculation
The following section shows the actuator weight estimation and
calculations to find the torque required to deflect the control surface.
6.4.1 Actuator weight estimation
To estimate the weight of actuator a reverse engineering is performed
from existing electromechanical actuator of Parker Aerospace [27]. The
values such as actuator series, maximum torque, maximum travel
length, basic weight and weight for additional length etc. are tabularized
to find the weight of the actuator for a specific stroke. This weight is used
to get the required torque. Figure 6.4 shows the weight estimation for
0.35m stroke.
Figure 6.4: Actuator weight estimation
6.4.2 Torque calculations
The torque values are calculated from the equations [13] in Dymola. The
equations used are as shown in section 9.7. A conceptual EMA is as
shown in Figure 6.5(a) [23] and the forces in contact between thread and
nut are as shown in Figure 6.5(b) [13].
The dynamic model is first simulated with the default parameters
available in the respective components. The Mass data from the
geometric model is obtained in CATIA. These values are then sent to the
dynamic model via user interface. In the dynamic model; the force
required to extend the flap is obtained and this value is used to find the
torque and power required.
43
Figure 6.5 (a) Conceptual EMA
Where
M= Mass [Kg]
F = Force [N]
α = Half Outer Angle [deg]
β = Inner Thread angle [deg]
φ = Elevation angle [deg]
ρ = Friction angle [deg]
µ = Friction Coefficient
N = frequency [Rpm]
P = Pitch [mm]
Figure 6.5 (b) Forces in contact in the thread
between the screw and nut
44
45
7. USER INTERFACE
Integration has been made between CATIA and Dymola by customized
frame work developed in Excel. Many people have the knowledge of
Excel, thus this user interface is powerful and the design parameters can
be managed easily. As all the required parameters can be modified at one
place, this can save time during the design process. The workbook is
connected to CATIA and Dymola via VB script. The source code is written
entirely in Visual Basic.
Figure7.1: Tool integration framework for control surface design
46
7.1 CATIA User Interface
In this user interface all the values for the control surfaces can be
modified as per the user specification. Figure 7.2 shows the CATIA user
interface. Aileron, elevator, rudder and flaps can be designed by using
this interface. The wing is divided into two sections [15], in-board flap is
designed by taking the references from the first section, aileron and outboard flap are designed by taking the references from second section.
Elevator and rudder are created by taking the reference from their
respective sections.
Figure 7.2: CATIA User Interface
7.2 Dymola User Interface
Interface integration is made by creating a customized framework in
Excel for CATIA and Dymola. The Workbook is divided into the following
sheets:
• Design Parameter sheet in which the user can modify the control
surface features in the CATIA_Excel_Dymola section as shown in
Figure 7.3.
• Actuator library sheet with physical data to estimate weight.
• Torque calculation sheet for a known weight of the actuator.
47
Figure 7.3: Excel user interface for control surface design for Dymola
The geometrical parameters are taken from the CAD model and then
exported to the Dynamic model.
48
49
8. DISCUSSION AND CONCLUSION
Parametric Aircraft framework is conducted at the department of
machine design using in house facilities. It consists of parametric models
which represent a large variety of aircraft concepts and has been
increased by adding parametric control surfaces. The main components
in this approach are:
• An extremely variable geometrical model that is capable of showing
a wide range of variants parametrically.
• A parametric dynamic simulation model that represent the CAD
model
• A framework for incorporation of the models and execution of the
design process through one User interface.
The CAD model and Inverse dynamic model developed and discussed in
sections 5 and 6 illustrates the following:
• Visualizing the shape of the parametric geometric model.
• A kinematic model in CAITA able to simulate the motion of the
control surfaces.
• The inverse dynamic model in Dymola showing the aircraft
dynamic performance.
• The mass data can be obtained from the parametric model in
CATIA and sent to the dynamic model in Dymola.
The analysis in section 9.1 shows that the control surfaces can be
adapted for different range of aircrafts such as Cessna CJ4, Embraer
145, and Boeing 777 etc. An Inverse dynamic model of the actuator
system is developed using the data obtained from the CAD model, such
as mass, inertia and center of gravity. These values are then transferred
to the dynamic model through the User interface.
It has also been illustrated that by using the User interface the critical
design parameters can be managed in one spreadsheet. Changing the
design parameters in the User interface, automatically executes the
required CAD and dynamic model within a short period of time. EMA is
50
considered in the dynamic model. EMAs are used in primary flight
control by considering their power, density, cost and weight factors.
Further research can be done on automatic selection of mechanism and
actuators for the proposed aircraft configuration.
51
52
9. APPENDIX
9.1 Different aircraft configurations
In this section different types of aircraft configurations are shown to
emphasis on the mobility of the control surfaces. (For the source of
figures on the left hand side refer [31])
Figure 9.1: Cessna Citation
Figure 9.2: Embraer 145
53
Figure 9.3: Boeing 777
9.2 Knowledge advisor
Rule Function
Check Function
Reaction Function
Parameter Set
Parameters
Derived Variable
Relation Set
Parameter Set Function
Relation Set Function
Rule
Reaction
Check
Formulas
Object Parameters
Derived Object Variables
Formula Function
Figure 9.4 user interface of Knowledge Advisor
54
9.3 Adaptability of the aileron
Figure 9.5: Aileron leading edge parallel to the rear spar of the wing
Figure 9.6: Constant-Percent chord (refer Figure 1.4)
Figure 9.7: Square aileron extending until trailing edge
55
9.4 Procedure for modification of the mechanism
A brief procedure is provided for modification of mechanism to suit with
the different aircraft models. The procedure is shown for the In-board
flaps and the same follows for the Out-board flaps.
•
Export the values through the User Interface to CATIA, Update the
model in CATIA. Export the values of the control surfaces and
update in CATIA.
•
An error occurs when updating the CAD model, deactivate the
Ignored constraint in the In-board or Out-board Mechanism
assembly and update the CAD model. Update diagnosis of the CAD
model is shown in Figure 9.8, deactivate the ignored constraints
and update the model.
Figure 9.8: Ignored constraints
•
Open the Inboad_Flap_Mechanism.Assembly in a new window; use
the Hide/Show button to see the mechanism. The mechanism will
look as shown in Figure 9.9.
Figure 9.9: In-board flap mechanism before modifying
56
•
Increase length of the chord of the aerofoil and length of the Link,
also activate constrains that were previously deactivated and
update the model. The model is as shown in Figure 9.10.
Figure 9.10: In-board flap mechanism after changing values
•
If the flap is not oriented properly [Figure 9.10] then increase the
length of the link. Later modify the ‘Angle.58’ in constrains so that
the chord of the flap is parallel to the guide line as shown in Figure
5.16.
Figure 9.11: In-board flap mechanism after modifying
•
The final modified mechanism is as shown in Figure 9.11. Figure
9.12 shows the modified parametric model from Citron CJ4 to
Embraer 145.
Figure 9.12: Citron CJ4 to the left and Embraer 145 to the right.
57
9.5 Dynamic simulation model
Figure 9.13(
9.13(a)
a) Aircraft dynamic simulation model with default parameters (before and after simul
simulation)
ation)
Figure 9.13(b) Aircraft dynamic simulation model with mass data from CATIA (before and after simulation)
Figure 9.13: Dynamic simulation model
9.6 Visual Basic code for automatic instantiation of the
ribs
9.6.1 Deleting Instantiate of ribs
Sub main
Set documents1 = CATIA.Documents
Dim stringPartName
stringPartName = "Inboard_Flap_Ribs"
Set partDocument1 = documents1.Item(stringPartName & ".CATPart")
Set
Set
Set
Set
Set
Set
part1 = partDocument1.Part
parameters1 = part1.Parameters
Relations1 = part1.Relations
hybridBodies1 = part1.HybridBodies
productDocument1 = CATIA.ActiveDocument
selection1 = productDocument1.Selection
58
selection1.Clear
Set
Set
Set
Set
Set
Set
stringlParam1 = parameters1.Item("To_Initiate")
stringlParamName = parameters1.Item("Hybrid_Name")
stringlParamParam = parameters1.Item("Parameter_to_Initiate")
realParamNr = parameters1.Item(stringlParam1.value)
realParamNew_Nr = parameters1.Item("New_" & stringlParam1.value)
realParamInitiate = parameters1.Item("Initiate")
if realParamNr.value<realParamNew_Nr.value then
For I_nr = realParamNr.value+1 To realParamNew_Nr.value
Set R1 = Relations1.Item("Product_Relations." & I_nr )
selection1.Add R1
selection1.Delete
Set hybridBody1 = hybridBodies1.Item(stringlParamName.value & "." & I_nr)
selection1.Add hybridBody1
selection1.Delete
Set realParam3 = parameters1.Item(stringPartName &"\" & stringlParamParam.value &
"." & I_nr )
selection1.Add realParam3
selection1.Delete
Next
realParamNew_Nr.value = realParamNr.value
part1.Update
Elseif realParamNr.value > realParamNew_Nr.value then
For I_nr = realParamNew_Nr.value +1 To realParamNr.value
Set hybridBody1 = hybridBodies1.Add()
hybridBody1.name = stringlParamName.value & "." & I_nr
realParamInitiate.value = realParamInitiate.value + 1
Next
realParamNew_Nr.Value = realParamNr.Value
part1.Update
End if
End sub
9.6.2 Instantiation of ribs
Sub main
Set documents1 = CATIA.Documents
Set partDocument1 = documents1.Item("Inboard_Flap_Ribs.CATPart")
Set PartDest= partDocument1.Part
Catia.SystemService.Print "Retrieve the factory of the current part"
59
Dim factory As InstanceFactory
Set factory = PartDest.GetCustomerFactory("InstanceFactory")
Catia.SystemService.Print "BeginInstanceFactory"
factory.BeginInstanceFactory
"Initiate_UDF", "e:\tmp\ Inboard_Flap_Ribs.CATPart"
Catia.SystemService.Print "Begin Instantiation"
factory.BeginInstantiate
Catia.SystemService.Print "Instantiate"
Dim Instance As ShapeInstance
Set Instance = factory.Instantiate
Catia.SystemService.Print "End of Instantiation"
factory.EndInstantiate
Catia.SystemService.Print "Release the reference document"
factory.EndInstanceFactory
Catia.SystemService.Print "Update"
PartDest.Update
End sub
9.7 Torque calculations in Dymola
model Actuator_calculations_1
Modelica.SIunits.Torque Tau;
parameter Modelica.SIunits.Diameter d2=0.018;
parameter Modelica.SIunits.Radius r2=0.009;
Modelica.SIunits.Angle phi;
parameter Modelica.SIunits.Length p=0.004;
constant Real pi=3.14159265358979323846264338327950288419716939937510;
Modelica.SIunits.Angle rho;
parameter Modelica.SIunits.CoefficientOfFriction mu=0.15;
parameter Modelica.SIunits.Angle alpha=15;
Modelica.SIunits.Power P;
Modelica.SIunits.AngularVelocity Omega;
parameter Modelica.SIunits.Frequency n=60;
Modelica.Blocks.Interfaces.RealInput F annotation (extent=[-102,-12; -62,28]);
equation
60
phi=arctan(p/(pi*d2));
rho=arctan(mu/cos(alpha));
Tau=abs(F)*r2*tan(phi+rho);
Omega=( 2 * pi * n)/60;
P=Omega*Tau;
annotation (Diagram);
end Actuator_calculations_1;
61
62
10. REFERENCES
[1] E.T Raymond, C.C.Chenoweth, Aircraft Flight Control System
Actuation System Design, Warrendale, PA: Society of Automotive
Engineers, cop. 1993.
[2] Ian Moir, Allan Seabridge, Aircraft systems: mechanical, electrical and
avionics subsystems integration, Chichester: Wiley, cop. 2008
[3] Peter A. Fritzson, Principles of object-oriented modeling and
simulation with Modelica 2.1, New York; Chichester: Wiley, cop. 2004
[4] Michael C. Y. Niu, Airframe structural design: practical design
information and data on aircraft structures, Hong Kong: Conmilit, cop.
1988
[5] Denis Howe, Aircraft Conceptual
Professional Engineering, 2000
Design
Synthesis,
London:
[6] Daniel P. Raymer, Aircraft design: A conceptual approach,
Washington, D.C: American Institute of Aeronautics and Astronautics,
cop. 1999
[7] System Engineering Fundamentals, Defense Acquisition University
Press, 2001
[8] Wendy Horobin, How It Works: Science and Technology, Marshall
Cavendish, 2003
[9] A computer model used to calculate the horizontal control surface size
of a conceptual aircraft design, National Aeronautical and Space
Administration, August 1990
63
[10] American Institute of Aeronautics and Astronautics, AIAA aerospace
design engineers guide, Reston, Va. American Institute of Aeronautics
and Astronautics, 2003
[11] Phillip L. Skousen, Valve Handbook, New York: McGraw-Hill, c2004.
[12] Jan Roskam, Airplane Design, Ottawa, Kan.: Roskam Aviation and
Engineering, 1985-1990
[13] Karl-Olof
(Slovenien)
Olsson,
Maskinelement,
Stockholm:
Liber,
2006
[14] A. Garcia, I. Cusid6, J.A. Rosero, J.A. Ortega, L. Romeral, Reliable
Electro-Mechanical Actuators in Aircraft, MCIA Research Group,
Electronic Engineering Department, UPC
[15] Tarkian, M., Ölvander, J., and Berry, P., Exploring Parametric CADmodels
in
Aircraft
Conceptual
Design,
49th
AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and
Materials Conference, Schaumburg, IL, 7 - 10 April 2008
[16] Amadori, K., Jouannet, C., Krus, P., A Framework for Aerodynamic
and Structural Optimization in Conceptual Design, 25th AIAA Applied
Aerodynamics Conference, Miami, FL, June 25-28, 2007
[17] Modelica Association, “Modelica A Unified Object-Oriented Language
for
Physical
Systems
Modeling,
Language
Specification,
http://www.modelica.org, 1999.
[18] Tarkian, M., Ölvander, J., Lundén, Björn., Integration of parametric
CAD and dynamic models for Industrial robot design and optimization,
ASME 2008 International Design Engineering Technical Conferences &
Computers and Information in Engineering Conference IDETC/CIE 2008,
August 3-6, 2008, Brooklyn, New York, USA
[19] Elmqvist E., Brück D., and Otter M., Dymola - User's Manual,
Dynasim AB, 1999.
[20] Otter, M. Elmqvist, H. and Mattson S.E., “The New Modelica
MultiBody Library”, in Proceedings of the 3rd International Modelica
Conference, Linköping, November 3-4, 2003.
64
[21] S L Merry, M J Large, T J Whitten, M R Wilkinson and R J Babb,
Control Surface and Actuator Design for a Low Drag, Laminar Flow AUV,
0-7803-3 185-0/96, IEEE, 1996
[22] Martin J.Brenner, Actuator and Aerodynamic Modeling for HighAngle-Attack Aeroservoelasticity, NASA Technical Memorandum 4493,
June 1993
[23] Olaf Cochoy , Susan Hanke, Udo B. Carl , Concepts for position and load
control for hybrid actuation in primary flight controls , Aerospace Science
and Technology 11 (2007) 194–201
[24] http://www.dynasim.com/
[25] http://www.invenia.es/
[26] http://www.moog.com/
[27] http://www.parker.com/
[28] http://www.allstar.fiu.edu/
[29] [http://www.3ds.com/
[30] http://www.wikipedia.org/
[31] http://www.airliners.net/
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