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Further info for modal analysis shell

Altair Forum User

I'm trying to benchmark an optistruct analysis against other results for a relatively simple normal analysis of a shell.

As the results are not really as expected, I am wondering where I would be able to find more information about the type of shell element used. I checked the PShell property information sheet but that doesn't really help.

Similarly I'm wondering if there is further information available about EIGRL except for the bulk data entry page?

Thanks a lot!

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tinh

I'm trying to benchmark an optistruct analysis against other results for a relatively simple normal analysis of a shell.

As the results are not really as expected, I am wondering where I would be able to find more information about the type of shell element used. I checked the PShell property information sheet but that doesn't really help.

Similarly I'm wondering if there is further information available about EIGRL except for the bulk data entry page?

Thanks a lot!

Hi, there

You can type 'CQUAD4', 'CTRIA3' on Optistruct reference help for information about element types

What kind of further information about EIGRL do you want?

Altair Forum User

Thanks a lot for your reply tinh, I believe I figured out what I need to know about EIGRL and EIGRA by now.

I still can't get my results to match the ABAQUS results (that are confirmed by an analytical solution) though. Both OS (EIGRL) and Abaqus use the same Lanczos method to extract frequencies and eigenvalues, but my results remain different. I did a parametric analysis of mesh size but that didn't change much and played around with all possible parameters I can imagine.

I thus think that the difference might come from the shell element selection, especially as the analysis is done for a particularly thin shell. I'm using the cquad8 element now and found it's documentation file, but I can't figure out if this element is suitable to use for thin shells?

Any suggestions would be much appreciated!