Triaxial Accessories for Rock Mechanics Testing

Triaxial Accessories for Rock Mechanics Testing
Triaxial Accessories for Rock Mechanics Testing
Replicate in situ conditions with exceptional accuracy
Triaxial testing solutions
»» Triaxial cells
»» Confining pressure intensifiers
»» High-temperature controls
»» In-vessel load cells
»» In-vessel extensometers
»» Pore pressure intensifiers
»» Ultrasonic Velocity equipment
Geomechanical testing experts use MTS
Model 815 and 816 Rock Mechanics Test
Systems to test all types of rock in a wide
variety of applications. One of the more
challenging applications is triaxial testing,
which aims to accurately recreate high
confining pressures, high temperatures,
high pore fluid pressures, and a wide
range of stress states.
For these applications, MTS offers
triaxial testing assemblies that can be
integrated within a rock testing system
to create a complete triaxial testing
solution. These assemblies include
triaxial cells, a type of pressure vessel,
along with a wide array of in-vessel
accessories designed to withstand
extreme conditions.
Like all MTS products, triaxial accessories
for geomechanical testing incorporate
proven, high-quality components that
are designed to meet rigorous industry
standards and optimized to improve both
the quality and efficiency of rock testing.
be certain.
Characterize Rock Specimens in Natural States
Triaxial test assemblies from MTS accommodate a wide range of
specimen dimensions and pressure ratings. To create a system for
your specific application, choose a triaxial cell that accommodates
specimen dimensions (with instrumentation attached) and
features a confining pressure rating that matches the pressures
of the specimen’s actual environment. Then add triaxial testing
accessories according to your application needs. Some accessories,
such as the temperature control package, should be added to the
base system at the time of manufacture. Others, such as in-vessel
load cells, in-vessel extensometers and pore pressure intensifiers,
are easily installed in your lab.
Model 656 Series Triaxial Cells
Confining pressure intensifier
High-temperature control package
The core of the triaxial cell assembly is the
triaxial cell itself. Series 656 Triaxial Cells
are fully compatible with the MTS Model
815 and 816 systems. Features include:
The confining pressure intensifier
provides closed-loop control of the
confining pressure on the specimen.
FlexTest® digital controls precisely
manage a servovalve mounted on the
intensifier. Features include:
This package allows test engineers to
monitor and control temperature inside
the triaxial cell. It uses a cascade control
concept, where the output of one controller
is used as the command signal to a second.
The package includes heater bands and
heater cartridges, which are attached to
the triaxial cell assembly. Multiple
thermocouples inside the vessel and
attached to the specimen are connected
to an outer loop feedback circuit for
control, and also to a temperature display
panel for monitoring temperature gradient,
signal conditioning and data acquisition.
»» 140 MPa (20,000 psi) confining
pressures, available with optional
high-temp control package
»» Console mounting for safe operation
»» 200 MPa (30,000 psi) available at
ambient temperature only
»» Control panel with intuitive valve
»» In-vessel spherical seat standard with
select platen configurations
»» Pressure transducer and Temposonics®
displacement transducer
»» Up to 20 feedthroughs for in-vessel
measurement and control
»» Integration with FlexTest digital controls
»» Track and carriage assembly for easy
removal and storage
»» Integrated hydraulic lifts that raise
and lower the triaxial cell on MTS
Model 815 systems
»» Transparent reservoir for checking
fluid level and condition
»» Integrated air pump for filling and
»» Optional Hastelloy® feedthroughs,
tubing, and end caps for corrosive
pore fluids
Display modules accept thermocouple
input and provide analog output with
+/- 0.5°C accuracy. The package stores
maximum and minimum temperature
levels, takes up to 12 samples per second at
60 Hz (or 11 samples per second at 50 Hz),
and displays up to six digits. The entire
package includes:
»» Temperature capability to 200°C (400°F)
»» Multiple thermocouples for monitoring
temperature gradient in vessel
»» External heater bands
Triaxial cell assemblies
help simulate in situ
stresses, temperatures
and pore fluid pressures.
»» Lower platen heater cartridges
»» Cell assembly insulation shroud
»» Ceramic insulation plate
»» Temperature display panel, which
holds up to three programmable
display modules
»» Heater power distribution box with
over-temperature protection
»» Cables
In-vessel load cells
All MTS in-vessel extensometers deliver:
Ultrasonic Velocity Test Solution
MTS in-vessel strain-gaged load cells
provide a direct reading of the axial force
applied to the specimen, minimizing
potential errors due to seal friction and
pressure area effects. Maximum operating
pressure is 140 MPa (20,000 psi) and
maximum operating temperature is 200°C
(400°F). These load cells are compatible
with approved mineral and synthetic oil
confining fluids. Features include:
»» Exceptional accuracy and stability
»» Robust design for high-pressure and
high-temperature environments
Pore pressure intensifier
The MTS Ultrasonic Velocity Test Solution
measures dynamic elastic properties of
core samples under changing stress states.
It enables detailed characterizations of
specimens, yielding insight into porosity,
permeability, grain structure, deformational
stress and other attributes. The solution
includes state-of-the-art platen hardware,
application software and electronics for
control and data acquisition. These
components are engineered to deliver
accurate, dependable performance in
triaxial test applications at temperatures
up to 120°C (248°F) and pressures up to
140 MPa (20,000 psi). The entire solution
allows test engineers to:
»» Single- or dual-bridge wiring
»» Compact design for easy installation
In-vessel extensometers
MTS in-vessel extensometers measure
strains on specimens at high pressures
and temperatures. They provide outstanding
accuracy, control and durability, and are
ideal for all types of testing, including
uniaxial compression-tension, hydrostatic
compression, triaxial stress, calculated
variable strain control, extension testing
and thermal expansion.
MTS axial testing extensometers clip onto
specimens to measure strain over clearly
defined gage lengths and avoid specimenplaten interactions. Configurations include
single-bridge with single output and
dual-bridge with dual outputs measuring
strain at points 180° apart on the specimen.
Outputs from dual-bridge extensometers
can be recorded separately or averaged.
MTS circumferential extensometers feature
a unique stainless-steel roller chain for low
hysteresis and high repeatability. These
extensometers measure circumferential
strain deformation that diametral
extensometers can miss when local
“slabbing” of the specimen occurs. Chain
rollers and offset links can be added or
removed in increments of 6.35 mm (0.25 in)
to accommodate a variety of specimen
diameters, and a zero adjustment pin
allows fine-tuning.
MTS axial extensometers can be mounted
simultaneously with circumferential
extensometers in all MTS triaxial cells.
»» Temperature compensation over a
wide range of operating temperatures
»» Fast easy installation and removal
»» Heat-shrink Teflon® or thin Viton®
jackets to minimize jacket effects
»» Rugged design that withstands
extreme conditions
The pore pressure intensifier is used to
saturate jacketed specimens, pressurize and
control pore fluid in the specimen, and
allow for permeability measurements. It is
mounted in a console, where a diagram on
the control panel indicates the function of
each valve. FlexTest digital controls operate
a servovalve mounted on the intensifier
manifold. Together, a pressure transducer
and integrated Temposonics displacement
transducer provide feedback for control,
allowing the intensifier to be operated in
stroke control, which is proportional to
volume, or in pressure control.
»» Calculate dynamic Young’s modulus,
shear modulus and Poisson’s ratio
»» Enhance materials testing flexibility
»» Improve predictions of overall rock
mass properties
The intensifier assembly uses a singleended actuator with unequal piston areas.
Fluid pressurized by the intensifier is
applied to one or both ends of the specimen.
Operators can perform drained and
undrained tests, and the Temposonics
displacement transducer allows calculation
of the pore fluid flow rate.
A Transient Permeability pore pressure
intensifier is also available to measure the
permeability of the specimen by raising
each end of the specimen to a different
pressure and measuring the pressure decay
of the two ends over time. Features of these
intensifiers include:
»» Console mounting for safe operation
»» Intuitive valve diagram for easy control
of fluid
»» Pressure and displacement transducers
for closed-loop servocontrol
»» Integration with FlexTest digital controls
»» Transparent reservoir for easy
monitoring of fluid level and condition
»» Optional design for corrosive pore fluids
The Ultrasonic Velocity triaxial platens propagate a
compression wave and two orthogonal shear waves
along the longitudinal axis of the core sample. The
system then measures the time of flight through the
specimen, calculating dynamic elastic properties that
can be compared to static properties collected using
traditional techniques.
Take full advantage of MTS expertise
Upper Vent
Triaxial test applications require the
complex integration of a rock mechanics
test system, triaxial cell and accessories.
MTS has extensive experience
implementing these challenging test
configurations in both standard and fully
customized systems, and we understand
the critical issues related to system
integration. Our field engineers can help
ensure all components are optimized for
your application, which facilitates precise
control and accurate measurement, and
also helps reduce risk and increase
confidence in results.
Pressure Vessel
Upper Confining Fluid Port
Pressure Relief Valve
In-vessel Load Cell
End Cap Seal
Upper End Cap
Upper Pore Pressure Line
Specimen & Extensometers
Lower End Cap
Learn more today
Contact your MTS representative to learn
more about how MTS Triaxial Accessories
for Rock Mechanics Testing can optimize
your testing program.
Cable Feedthroughs
End Cap Seal
Pore Pressure Ports
Special Use Ports
Lower Vent
Lower Confining Fluid Port
Typical Triaxial Cell Assembly
(Model 656.06 assembly shown)
Specifications for MTS Series 656 Triaxial Cells*
656.04 Maximum confining/pore pressure
656.05 656.06
80 MPa (12,000 psi) 140 MPa (20,000 psi)
140 MPa (20,000 psi)
70 MPa (10,000 psi) 140 MPa (20,000 psi)
Inside diameter
190 mm (7.5 in)
165 mm (6.5 in)
190 mm (7.5 in)
140 mm (5.5 in)
140 mm (5.5 in)
Maximum specimen diameter
102 mm (4 in)
54 mm (2.125 in)
102 mm (4 in)
54 mm (2.125 in)
54 mm (2.125 in)
Maximum operating temperature
200°C (400°F)
200°C (400°F)
200°C (400°F)
175°C (347°F)
175°C (347°F)
Use Load Frame Model:
315.0X315.04 315.04 316.0X316.0X
Extension Testing Capacity
*Contact MTS for the 200 MPa (30,000 psi) Triaxial Cell specifications and configuration options.
MTS Systems Corporation
14000 Technology Drive
Eden Prairie, MN 55344-2290 USA
Telephone: 1.952.937.4000
Toll Free: 1.800.328.2255
Fax: 1.952.937.4515
E-mail: [email protected]
ISO 9001 Certified QMS
Specifications subject to change without notice.
MTS, FlexTest, and Temposonics are registered trademarks of MTS
Systems Corporation within the United States. These trademarks may
be protected in other countries. RTM No. 211177.
© 2015 MTS Systems Corporation.
100-213-762 TriaxialAccessories Printed in U.S.A. 4/15
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