MTS Multipurpose Elite - Manual (Page 210)

3. Expand the nominal end index away from the start index until the new modulus value differs from the
nominal modulus by more than 2%.
4. The endIndex is set before the newly calculated modulus exceeds the nominal modulus.
If variables represent this field in the function and the original value is -1, the variable contains the calculated
index at the completion of the function.
Cycle Modulus
CycleModulus(Stress, Strain[, startIndexLoading, endIndexLoading, startIndexUnloading,
endIndexUnloading])
CycleModulus returns the average of LoadingModulus and UnloadingModulus.
First Cycle Modulus
FirstCycleModulus(Stress, Strain[, startIndex, endIndex])
The FirstCycleModulus function returns the modulus of the data in the region prior to the first peak or valley
because the first cycle is typically a partial cycle. The modulus is either a loading or unloading modulus,
based on an increase or decrease in the specimen load during the first cycle.
Fatigue Life Calculation Function
Fatigue Life
FatigueLife(YAxis, XAxis, startIndex, endIndex, percentageDrop)
The FatigueLife function returns the index of the point where the material under test fails. The failure point
is after endIndex where the Y-Axis value falls below (percentageDrop) the Least Squares Fit line of X-Axis
and Y-Axis data between startIndex and endIndex. This function provides the drop line for the Failure
Cycle Chart.
Calculated Variable Functions
Calculation Editor
Access
1. Click the Variables tab.
2. Double-click the calculated variable you want to edit. Or, if you are creating a new variable, select the
Is Calculated check box in the Calculation panel.
210 | MTS TestSuite
Working with Variables