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PSD fatigue model chekcing

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 I made a PSD fatigue model based on my understanding to Optistruct, but I do not know whether this is the right setting, I see the stress PSD and RMS stress is similar with Patran, but I am not sure about the fatigue damage results, is there someone who can help me to check?

Thanks a lot!



In my model, a simple beam is built, on the tip of this beam, a 0.2kg mass is added. Then the other end of this beam is fixed, and the PSD loads in here is 0.475G^2/Hz from 20Hz to 200Hz, this random test keeps for 4 hours.


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Please make sure to keep the unit consistent. Refer the below post where we shared best practices for random response analysis.



Some Tips for results comparison with other solver
• Use “Amplitude” in MATFAT (default is “range” in OS)

• Request for “Damage” results on elements in other solvers

• Define right option for PSD input  for random vibration fatigue (Log vs linear) 


Attached Random Fatigue deck for your reference.


Note: OptiStruct supports Random Fatigue Analysis only Uniaxial SN with Von-Mises stress and approximated principal stress


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