Element (PLESOL) and Nodal (PLNSOL) stress plots giving different results than ETABLE

[DavidMechE]

I am performing a response spectra calculation of a component composed of Beam44 (legacy model) and Shell63 elements. Looking at the stress intensity using PLESOL and PLNSOL results in a much larger (almost 2x) max stress intensity then when I sort an ETABLE containing stress intensity. I am finding that the ETABLE results are less than the element or nodal plots pretty consistently. I have made sure /GRAPHICS,Full is on and I have tried to used SUMTYPE,PRIN but it still produces the different values. Does anyone have any explanation why the ETABLE and the PLESOL wouldn't produce the same result or how I can resolve?

 

[beastgod]

I don`t know exactly, whether I can help you or not.
But here I tried to compare results in Nodes and Elements (in Russian). And this link lead to the one more similiar presentation (in English).
May be you can find answers to your question...
I would be glad if I can help!

 

[Drej]

ETABLE stresses are generally from element integration points, whilst PLESOL and PLNSOL are (extrapolated) and (extrapolated and averaged), respectively, to the nodes, hence higher than the integration point values.


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[DavidMechE]

Thank you both for your responses.

Because the differences in the stresses is so great (~150 MPa vs ~90 MPa max stress intensity) do you think that means that my mesh needs refinement? It seems that that sort of difference in stress is a little disconcerting.

 

[Drej]

I would expect you need to check for mesh convergence, yes. You can check this by looking at the stresses as a result of issuing PLNS and PLES and comparing the difference in values. For the stress to be that different (150 vs 90) in the same location you must be looking at some geometric feature and/or high gradient point and/or have quite a poor mesh resolution.


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