- #1

FEAnalyst

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- TL;DR Summary
- How can one calculate fatigue life for a complex model based on results obtained from linear static FEA ?

Hi,

advanced FEA programs allow their users to perform fatigue analyses. However, there are still many programs where such simulations can't be performed. I've heard that in such case one can use results obtained from regular linear static FEA to calculate fatigue life manually. Theoretically maximum stress (Mises or principal ?) could be compared with Wöhler curve of the material to obtain minimum fatigue life. However, there are two main issues:

- how to do it in case of geometrically complex models (machine parts) subjected to complex loading (not just simple tension/compression, bending or torsion) ?

- how to do it in case of loading other than fully reversed so that we have to account for mean stress effects ?

Is it possible to account for these factors in hand calculations based on stress from linear static FEA ? If yes then how to do it and which formulas should I use ? Where can I find some examples ?

advanced FEA programs allow their users to perform fatigue analyses. However, there are still many programs where such simulations can't be performed. I've heard that in such case one can use results obtained from regular linear static FEA to calculate fatigue life manually. Theoretically maximum stress (Mises or principal ?) could be compared with Wöhler curve of the material to obtain minimum fatigue life. However, there are two main issues:

- how to do it in case of geometrically complex models (machine parts) subjected to complex loading (not just simple tension/compression, bending or torsion) ?

- how to do it in case of loading other than fully reversed so that we have to account for mean stress effects ?

Is it possible to account for these factors in hand calculations based on stress from linear static FEA ? If yes then how to do it and which formulas should I use ? Where can I find some examples ?