Prestressed frequency analysis is not supported in Beam interface

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Hi,

when I analyze a shell-truss-beam coupling system by 5.5 version, a error always appearred as 'Prestressed frequency analysis is not supported in Beam interface'. but if I use 5.4 version to analyze this problem, the error will not appear. Do you have any ideas about this? Thanks very much for your help.

Lin


3 Replies Last Post 2020年7月10日 GMT-4 上午4:22
Henrik Sönnerlind COMSOL Employee

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Posted: 4 weeks ago 2020年7月8日 GMT-4 上午7:10

It was never possible to take prestress effects into account in the Beam interface, but there was no warning message before.

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Henrik Sönnerlind
COMSOL
It was never possible to take prestress effects into account in the Beam interface, but there was no warning message before.

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Posted: 4 weeks ago 2020年7月9日 GMT-4 上午4:05

Dear Henrik, thank you very much.

I want to get the natrual frequency of a coupling system. This system includes beam, truss and shell. Acturally, prestress effects the truss obviously, but not beam. So I am trying to run the study of frequency domain, prestressed for the whole system. Then, there is a error messsage ' Prestressed frequency analysis is not supported in Beam interface. ' Would you share any ideas for getting the frequency of the whole coupling system? Thank you very much for your help.

Lin

Dear Henrik, thank you very much. I want to get the natrual frequency of a coupling system. This system includes beam, truss and shell. Acturally, prestress effects the truss obviously, but not beam. So I am trying to run the study of frequency domain, prestressed for the whole system. Then, there is a error messsage ' Prestressed frequency analysis is not supported in Beam interface. ' Would you share any ideas for getting the frequency of the whole coupling system? Thank you very much for your help. Lin

Henrik Sönnerlind COMSOL Employee

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Posted: 4 weeks ago 2020年7月10日 GMT-4 上午4:22
Updated: 4 weeks ago 2020年7月10日 GMT-4 上午5:17

Hi Lin,

The scenario which you outline here (where beams are present in a larger structure, but are not important from a prestress point of view) is of course meaningful.

There is no way to get past the error message in version, and it should not be possible, since we cannot guarantee that the results will be correct, even in your scenario.

In the future, the fact that beams are present in the model should generate a warning, not an error. One of our developers is looking into this. It is, however, not just a matter of changing the message. It must also be ensured that the stiffness matrices generated for the beams are not wrong.

If you send your model to support, it may be possible to find a workaround.

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Henrik Sönnerlind
COMSOL
Hi Lin, The scenario which you outline here (where beams are present in a larger structure, but are not important from a prestress point of view) is of course meaningful. There is no way to get past the error message in version, and it should not be possible, since we cannot guarantee that the results will be correct, even in your scenario. In the future, the fact that beams are present in the model should generate a warning, not an error. One of our developers is looking into this. It is, however, not just a matter of changing the message. It must also be ensured that the stiffness matrices generated for the beams are not wrong. If you send your model to support, it may be possible to find a workaround.

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