MTS Fatigue Analyzer - Manual (Page 62)

21. Select the Use Calculation check box and click Edit.
The Calculation Editor window opens.
22. Create the following calculation and click OK: FatigueCycles[FatigueLife
(FatigueLoadPeak,FatigueCycles,FindNearestValueIndex (FatigueCycles, \ StableCycle),
FindNearestValueIndex(FatigueCycles,CrackInitiationCycle),DropPercentage)].
FatigueLife is a function that returns the index of the data arrays matching the fatigue life failure.
FindNearestValueIndex is a function that locates the index of the closest value in an array to the search
value.
Other values in the calculation are variables. CrackInitiationCycle and StableCycle are fixed decimal
count-type variables. If you do not have a template, you may have to define them and estimate their values.
If you have a template, they may be part of the test definition.
Per-cycle data variables that have changing values must be mapped in the Data Acquisition Editor.
23. Right-click the analysis run in Test Editor and select View Data Acquisition Editor.
The Data Acquisition Editor opens. In the Select Data Acquisition box, click the drop-down button and
select Peak-Valley.
24. In the Additional Cycle Variable Calculations panel, select a variable to be updated and click the right
arrow button.
25. Repeat steps 23 and 24 until all required variables are in the right-hand panel.
26. Click the Refresh All Analysis Views button to update the variables in all analysis runs that use the analysis
definition.
27. Set up the Failure Cycle chart.
28. Click the drop-down button for the Y-Axis Data box and select Load Peak.
A graph opens in the work area.
29. Add a marker line to the view.
30. Click the drop-down button for the top Cycle box and select Stable Cycle.
The Stable Cycle marker and a drop line are added to the chart. The cycle number of the Stable cycle is
added near the word Cycle.
31. Click the drop-down button for Cycle 2 and select Crack Initiation Cycle.
New Marker 1 changes to Crack Initiation Cycle and moves. The crack initiation cycle number is added
near the word Cycle. The drop line may move.
32. Toggle to the variable selector.
33. Add a marker value; click the drop-down button and select Drop Percentage.
The drop percentage entry with parameter boxes appear.
34. Add a marker point; click the drop-down button and select Failure Cycle Number.
The cycle number of the specimen failure appears. The chart that results from this example resembles
the following.
62 MTS TestSuite™ Fatigue Analyzer User Guide
6.0 Data Analysis