Learning Forum

[Mattz1978]

Hello I am doing a fatigue analysis in ansys workbench. does anybody know for unidirectional fatigue load , in tension , in the material property (alternating and mean stress table ) should I use alternating stress or Max stress. In this case the minimum stress is zero.
I really appreciate your information in this regard

[peteroznewman]

Let's say your part has a maximum stress of 200 MPa, and a minimum stress of zero, and this part has a perfectly repeating cycle of this maximum and minimum. You can say that your part has an alternating stress of 100 MPa with a mean stress of 100 MPa.

Let's say you have fatigue data for the material only at zero mean stress, in other words, the material data had fully reversed stress.

You can use a mean stress theory to account for the mean stress in your part and calculate an equivalent alternating (fully reversed) stress so that you can use the zero mean stress material fatigue data that you have.

If you insert a Fatigue Tool into a Static Structural model, you can select from among a few mean stress theories after you configure it to a zero-based type of loading.

[Mattz1978]

Peter
Thanks for your clear explanation. I fully understood.

Thanks
Matt

[peteroznewman]

You're welcome Matt.

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