What Can the Fatigue Module Do?
The Fatigue Module is intended for fatigue analysis of structures. The term fatigue is used to describe the phenomenon where a component fails after repeated loadings and unloadings, even though the magnitude of each individual load is smaller than the ultimate stress of the material. The Fatigue Module is an add-on module to the Structural Mechanics Module.
Using the Fatigue interface, you can compute the risk of fatigue cracks occurring in a structure where the stress and strain state during a single load cycle has been computed. To perform such a fatigue analysis, you use the Fatigue interface along with one of the Solid Mechanics; Shell; Plate; Membrane; Solid Rotor; Solid Rotor, Fixed Frame; or Multibody Dynamics interfaces.
The stress results upon which the fatigue evaluation is based can come from different study types:
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Stationary (using load cases or parametric sweep)
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Time-dependent
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Frequency domain
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Random vibration
Eight basic types of evaluation can be performed:
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Stress-life analysis for high-cycle fatigue (HCF). The result is a lifetime prediction in terms of the number of cycles to fatigue.
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Strain-life analysis for low-cycle fatigue (LCF). The result is a lifetime prediction in terms of the number of cycles to fatigue.
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Stress-based analysis for high-cycle fatigue (HCF). The result is a usage factor, which tells you how close to the fatigue limit the load cycle is.
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Strain-based analysis for low-cycle fatigue (LCF). The result is a lifetime prediction in terms of the number of cycles to fatigue.
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Energy-based analysis when the dissipated energy controls crack formation and growth. The results are a lifetime prediction in terms of the number of cycles to fatigue and a dissipated fatigue energy density.
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Cumulative damage analysis for variable load fatigue. The results are usage factor, which tells you how close to the fatigue limit the load cycle is, counted stress cycles, showing the stress level distribution of the applied load, and the relative usage factor, showing the contribution to the overall fatigue usage from each stress level.
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Harmonic vibration analysis, based on the results from a frequency domain sweep. The result is a usage factor, which tells you how large fraction of the fatigue life that has been consumed by the cycles in the frequency sweep.
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Random vibration fatigue analysis, based on results from a random vibration analysis where the loading is represented by a PSD.