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Stress inconsistencies in MSC nastran loading in Femap

Stress inconsistencies in MSC nastran loading in Femap

Stress inconsistencies in MSC nastran loading in Femap


I'm using MSC Nastran to do a structural optimization with sol 200.

My model is made up of PSHELL(CTRIA3 and CQUAD4) andPBARL(CBAR) elements.

I've defined von mises stress responses by DRESP1 entry and I've linked them to the DCONSTR enty becouse I don't want elements overrides 233 MPa for the stress .

The optimization finished with hard convergence but there are some inconsistencies.

At the end of the file F06 there is the list of active stress responses for some elements.

If I consider one of those elements and I plot in Femap the model and the f06 ,the stress in the 'active stress response list' is different from the one in the final static analysis.

This happens only for CQUAD4 elements and not for the CBAR or the CTRIA3.

Can someone tell me why?

ps= I've tried to do the same with NX Nastran and there aren't insistencies between the list of active stress responses and the static analysis at the final cicle of the optimization. all the stress are the same considering one element for example.

I'd like to use NX but the problem is that I need to print in my f06 or in an external file the active stress responses like the figure I've attached.

Thanks a lot.

Best regards

RE: Stress inconsistencies in MSC nastran loading in Femap

Femap have different methods for data averaging. Try to set "Data Conversion" to "No Element averaging" or other option.

RE: Stress inconsistencies in MSC nastran loading in Femap

Hi, thank you for the reply.
I've change the options but this is not the problem.
I've noticed that the problem is when I define the stress item code for the CQUAD4.
I want to constraint the von mises stress but even if I use the correct item code nastran reads the constraints for the principal stress and not for von mises.
How can I recognize if my CQUAD4 element are CQUAD4 (33) or CQUAD4 (144)?
Is there a way to recall the type I want?
Because if I use CQUAD4 (144) than I've problem whit the CTRIA3 elements that doesn't support corner stress.
Best regards,

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