Fatigue dialog box

Option	Description
Name	Sets the name of the fatigue durability object. The durability object name is displayed in the event dialog boxes and the Durability Damage Evaluation dialog box.
Fatigue Life
Number of Occurrences	Sets how many times the event is repeated.Note: This option is not used by the Evaluate Damage command.
Fatigue Life Criterion	Specifies the fatigue life criterion that the durability solver uses to relate the amplitude of either the stress or strain cycle with the number of cycles of stress or strain to failure. See Fatigue life criteria for more information.
Include Mean Stress Effects	Available when Fatigue Life Criterion is set to Strain Life Maximum Principal, Stress Life, BWI, or TWI.Includes the mean stress effects in the fatigue life evaluation.If you select the Stress Life, BWI, and TWI methods, you must also specify an equivalent stress method for the durability solver to include the mean stress effects. Select the method you want from the Equivalent Stress Method list.See Maximum principal strain amplitude, Stress life with mean stress effects, and BWI criterion with mean stress effects for more information.
Weld Data	Appears when Fatigue Life Criterion is set to BWI or TWI.BWI Weld Class specifies the BWI weld class that is used to determine the BWI parameters in the BWI S-N curve.Option specifies how the number of standard deviations is defined.Number of Standard Deviations sets the number of standard deviations below the mean of the BWI S-N curve that the durability solver uses in the BWI and TWI fatigue life criteria. You set this value in the Number of Standard Deviations box.Probability of Failure sets the value for the probability of failure that the software converts into the number of standard deviations below the mean BWI S-N curve. You set this value in the Probability of Failure(%) box.See BWI fatigue life criterion for more information.TWI DataAppears when Fatigue Life Criterion is set to TWI. The TWI fatigue life criterion extends the BWI fatigue life criterion into the low cycle and high cycle fatigue regimes. Schematic of the TWI S-N curveIn the schematic of TWI S-N curve, the blue curve is the BWI S-N curve, the red curve is the TWI extension into the low cycle regime, and the green curve is the TWI extension into the high cycle regime.You need to specify the following unique TWI parameters.Non-propagating Stress Range specifies the number of cycles at the beginning of the non-propagating stress range, NNP.Non-propagating Stress Range Slope Change specifies the S-N curve slope change in the non-propagating stress range, δ.Low Cycle Stress Cutoff (Proportion of Yield Stress) specifies the stress at the low cycle cutoff, ΔσI.Low Cycle Stress Extension (Proportion of Yield Stress) specifies the stress at the end of the low cycle extension, ΔσII.See TWI fatigue life criterion for more information.
Use Plate Thickness Correction	Appears when Fatigue Life Criterion is set to Stress Life, BWI, or TWI.Uses the plate thickness correction in the fatigue life criterion.
Plate Thickness Correction	Appears when the Use Plate Thickness Correction check box is selected.Plate Thickness Ratio specifies the ratio between the thickness of the reference plate and the thickness of the plate under consideration. The thickness of the reference plate depends on international standards.Plate Thickness Exponent specifies the plate thickness exponent. This value should be between zero and one and depends on international standards.See Plate thickness correction for more information.
Notch Factor	Appears when Fatigue Life Criterion is not set to BWI or TWI.Use Notch Factor accounts for the local yielding in the fatigue evaluation. You must specify the value for the notch factor in the Notch Factor box. When the notch factor is set to 0.0, the software does not apply the notch correction to the nominal stresses and strains while computing fatigue.When you select the Use Notch Factor check box, you should perform the durability analysis only on elements that have local plastic behavior. You select the elements in the solve options durability object.See Using a notch factor for modeling the local plastic behavior for more information.
Cyclic Stress-Strain Model	Specifies the method that the durability solver uses to convert the amplitudes of stress cycles to and from the amplitudes of the strain cycles. See Understanding cyclic stress-strain behavior for more information.
Number of Elements in Hysteresis Loop	Sets the number of points representing the stress-strain hysteresis loop of the structure under a cycle.
Orthotropic Material Fatigue	Specifies the durability settings for performing fatigue life analysis on models that contain orthotropic materials.Perform Orthotropic AnalysisPerforms fatigue life analysis on orthotropic materials.Fatigue Life CriterionSpecifies the fatigue life criterion for orthotropic materials. The durability solver uses this criterion to relate the stress amplitude, S, with the number of stress cycles to failure, N.All orthotropic fatigue life criteria are stress-based.Mean Stress CorrectionSpecifies the mean stress correction method that is included in the fatigue life evaluation for orthotropic materials.See Orthotropic material fatigue analysis for more information.
Fatigue Life Output	Specifies the type of fatigue results the durability solver outputs.Select the Event Damage check box to obtain fatigue damage results at each element of free faces for the event.Select the Event Life check box to obtain fatigue life results expressed in cycles at each element of free faces for the event.See Durability results for the event-based analysis for more information.Note: This option is not used by the Evaluate Damage command.
Fatigue Safety Factor
Note: These options are not used by the Evaluate Damage command.
Fatigue Safety Factor Output	Output — Specifies the method that the durability solver uses to determine fatigue safety factor results. See Understanding the fatigue safety evaluation for more information.Method — Specifies the stress method that the durability solver uses when you set Output to either Goodman or Gerber:Select Amplitude and Mean when both stress amplitude and mean stress are varying.Select Amplitude when stress amplitude is varying.Select Mean when mean stress is varying.See Goodman and Gerber methods for more information.
Maximum Alternating Stress	Specifies how the durability solver calculates the maximum alternating stress. The maximum alternating stress is the stress amplitude needed to cause failure after a given number of cycles, using a standard polished specimen with a 6 mm diameter.CalculateLets the durability solver evaluate the maximum alternating stress using the specified number of cycles to failure and from the material S-N curve. See Fatigue life criteria for more information.You set the number of cycles to failure in the Cycles to Failure box.KeyinSets the maximum alternating stress to the value that you specify in the Maximum Alternating Stress box.See Computation of the maximum alternating stress for more information.
K-Factor	Sets the correction factor for the effects of surface finish, surface treatment, type of loading, and so on.
Fatigue Safety Factor	Specifies the fatigue safety factor results to be generated at each element of free faces for the event. See Durability results for the event-based analysis for more information.
Failure Index	Specifies the failure index results to be generated at each element of free faces for the event. See Durability results for the event-based analysis for more information.

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Fatigue dialog box, Simcenter 3D 2021.1 Series

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