MTS Material Test Systems - Manual (Page 45)

For balanced system operation, the load frame crosshead should be positioned so that the actuator piston
rod will be at approximately midstroke when the specimen is installed into its upper and lower grips/fixtures.
For detailed information on crosshead operation and specimen mounting considerations, refer to the load
unit product manual. Refer to the individual grip and fixture manuals for more information on installing these
components on the load frame.
6.2.2.0 Select and Set Up the Data Acquisition Equipment
Most data acquisition transducers and their associated readout and acquisition devices should be set up
before the system operating procedure is started.
The most common data acquisition transducers that are selected for specific testing applications are strain
gages. A strain gage measures the amount of specimen deformation and is typically bonded directly to specific
areas on the test specimen.
Refer to the appropriate product manual or vendor manual for further information on the setup of data
acquisition equipment.
6.2.3.0 Set Up the Counter
Select the counter end-of count function
When the test controller counter is enabled and its preset count is reached during testing, it can either activate
an interlock to stop the test or generate a rollover pulse to an external device (for example, an interrupt to a
computer). The desired end-of-count function must be selected before hydraulic pressure is applied to the
system.
Select the counter interlock function
The test controller counter contains an interlock that, if selected as the end-of-count function, will stop the
test when an end-of-count is reached. This interlock can be configured as a program or hydraulic interlock.
A program interlock stops only the program, while the hydraulic interlock stops the program and turns off the
hydraulic power supply.
When selecting the interlock function, consider the sensitivity of the test specimen. If, for example, an actuator
is to be mounted to a fragile specimen, then a program interlock would probably be most desirable. A hydraulic
interlock could cause the actuator to move when hydraulic pressure is removed and can damage the specimen
or invalidate the test results.
If the program interlock is selected, the counter can be used to stop the program at regular cyclic intervals
during testing. When the first interval end-of-count is reached, data can be recorded, the preset count can
be set to the next desired program stop count, and testing can be continued.
6.2.4.0 Set Up the Underpeak Detector
The test controller underpeak detector senses when a signal fails to reach a specified level. Although any of
the signals available for readout on the test controller can be selected as the underpeak detector input, the
typical selection is a test controller's transducer output (feedback) signal. The signal that is input to the
underpeak detector should be selected before hydraulic power is applied to the test system.
When selecting or changing the underpeak detector input, ensure that only one signal is selected as the input.
For example, if a displacement signal was selected for underpeak detection and load underpeak detection
is now selected, ensure that the displacement signal is deselected before hydraulic power is applied. If more
MTS Material Test System Operation 45
6.0 Getting Started