MTS Fracture Analyzer - Manual (Page 80)

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.
7.5.7.0 Strain and Stress Calculation Functions
Calculated Inelastic Strain
CalcInelStrain(Stress, Strain, Modulus)
The CalcInelStrain function returns the value: Strain - Stress/Modulus
The calculation provides the value of the Strain minus the Stress divided by the modulus. If Strain and Stress
are arrays, the result is an array. If Strain and Stress are single numbers, the result is a single number.
Hysteresis Area
HysteresisArea(StressArray, StrainArray)
The HysteresisArea function returns the area under the curve defined by the Stress and Strain array data.
Measured Inelastic Strain
MeasInelStrainMax(stressVar, strainVar)
MeasInelStrainMin(stressVar, strainVar)
The measured inelastic strain range is specific to materials fatigue testing, especially Low Cycle Fatigue
(LCF). The application calculates the mean stress from the stress and strain data that represents one cycle.
The two points where the mean intersects the curve determines the strain values. The MeasInelStrainMax
function returns the maximum of these two strain values. The MeasInelStrainMin function returns the minimum
of these two strain values.
StrainA
StrainA(StrainMax, StrainMin)
The StrainA function returns the value: ((StrainMax - StrainMin)/(StrainMax + StrainMin))
StrainR
StrainR(StrainMax, StrainMin)
The StrainR function returns the value: StrainMin/StrainMax
80 MTS TestSuite™ Fracture Analyzer User Guide
7.0 Variable Analysis