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Layer Selection for Stresses in PFAT

Hello,

I am conducting a Fatigue Analysis based on Transient Analysis in OptiStruct using Shell Elements.

I want OptiStruct to not take the Top or Bottom Layer but the Middle Layer for Fatigue Analysis. There is an entry CRTDIST in PFAT. It is not quite clear to me how this entry works.

Is it possible to make OptiStruct take the middle layer by entering T/2?

Thanks and best regards

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Altair Forum User

Hi,

You can specify the distance from the element surface by entering the value for CRTDIST (half of thickness for example)

Altair Forum User

Thanks Prakash for the quick reply.

Is there an information about of CRTDIST is calculated in case of 'AUTO'. For example I would like this entry to be calculated generally as T/2 for each and every element (thickness is nodewise assigned overall the model).

Altair Forum User

Hi @JD3640 When it is set to AUTO, CRTDIST takes a relation between E and fatigue limit. I will try to post the formula if possible.

Altair Forum User

Thank you, that formula would help a lot.