MTS Fatigue Template - Manual (Page 96)

Note:
With systems that use Series 494 hardware, you can use the HWI Editor application to select the arm
of the bridge where the shunt calibration resistor will be applied.
A current shunt calibration value, taken before a test, should be compared to the shunt calibration reference
value recorded when the sensor was last calibrated. If the reference value and the current value differ too
greatly, the sensor/conditioner pair should be recalibrated to establish a new shunt reference value.
Significant variations between current and reference values can occur if the excitation voltage has drifted, or
the sensor has been damaged or has changed in some other way. It is possible to adjust excitation to
compensate for small-to-moderate changes in the shunt calibration value.
Calibration overview
The calibration process coordinates the interaction between the transducer, a DC conditioning circuit, and a
cable. Calibration of a transducer is a two-step process:
First, a specific output of the conditioner is adjusted to a specific displacement of the transducer. This is
performed by adjusting the excitation voltage and amplification (gain) of the conditioner.
The second step verifies the output of the transducer conditioner versus a known standard displacement over
the entire range of measurement.
10.2.5.0 Verify the Extensometer
To verify the extensometer in the LCFS test:
1. Click Extensometer Verification in the Low-Cycle Fatigue Strain test.
A message appears: Click the Run button on the control panel to start the extensometer verification.
2. Click the Run button.
The Run button changes color and a message appears: Put the Extensometer in the zero position. Click
OK when ready.
3. Put the extensometer in the zero position and click OK.
4. Click OK.
The Verify Zero Strain Reading window appears. Accept the value or type an offset as necessary.
5. Click OK.
The Strain Full Scale window appears.
6. You may want to set this value to 0.1 and click OK.
The Extensometer Verification Prompt window appears.
7. Click to repeat the extensometer verification or click No to continue.
10.2.6.0 Modulus Check at Start Temperature
You should perform a modulus check before you run a test. The standard template allows you to check the
modulus at start temperature and test temperature (for elevated temperature tests). The start temperature
modulus check helps determine if the system is set up correctly. For example, if you have not pulled the zero
96 MTS TestSuite
10.0 ASTM Trapezoidal Strain Template