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Shaker comparison

Posted 09.03.2020, 07:00 GMT-4 Structural & Acoustics, Acoustics & Vibrations 3 Replies

Kevin Mann
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Hi all,

I would like to compare the displacement of different model at their eigenfrequency. I have done a eigrenfrequency analysis and want to apply thre respective eigenfrequency to the model. As the shaker will have the same displacement but the frequeny will vary, I would like to know if I can use the frequency domain and apply a given displacement to the boundaries clamped to the sahker or if I have to use an other method.

Thanks in advance.

3 Replies Last Post 09.03.2020, 16:33 GMT-4
Henrik Sönnerlind COMSOL Employee

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Posted: 5 years ago 09.03.2020, 11:20 GMT-4

Yes, you can use Prescribed Displacement in a Frequency Domain analysis. You will however have to transfer the eigenfrequencies to the input of the study manually. If you are going to do it for a large number of variants, you can consider using a Model Method to automate it.

Note that the response at the natural frequency is completely controlled by the damping, so a good representation of the damping is crucial to get any quantitative results.

See also https://www.comsol.com/blogs/frequency-response-of-mechanical-systems

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Henrik Sönnerlind
COMSOL
Yes, you can use Prescribed Displacement in a Frequency Domain analysis. You will however have to transfer the eigenfrequencies to the input of the study manually. If you are going to do it for a large number of variants, you can consider using a Model Method to automate it. Note that the response at the natural frequency is completely controlled by the damping, so a good representation of the damping is crucial to get any quantitative results. See also
Kevin Mann
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Posted: 5 years ago 09.03.2020, 13:32 GMT-4

Thank you for your answer, I will do it manually as it's just afew model thanks.

Concerning the damping, do I have to input a damping predifned or is it automatically done by the simulation?

Also I started comparing the values from the eigenfrequency model, do you know how the results are defined for the eigenfrequency study?

Thank you very much

Thank you for your answer, I will do it manually as it's just afew model thanks. Concerning the damping, do I have to input a damping predifned or is it automatically done by the simulation? Also I started comparing the values from the eigenfrequency model, do you know how the results are defined for the eigenfrequency study? Thank you very much
Henrik Sönnerlind COMSOL Employee

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Posted: 5 years ago 09.03.2020, 16:33 GMT-4

You need to enter the appropriate damping. You can find more information about structural damping in

https://www.comsol.com/blogs/damping-in-structural-dynamics-theory-and-sources
and
https://www.comsol.com/blogs/how-to-model-different-types-of-damping-in-comsol-multiphysics

Also I started comparing the values from the eigenfrequency model, do you know how the results are defined for the eigenfrequency study?

Which results are you referring to? For more information about eigenfrequency analysis, see also

https://www.comsol.com/multiphysics/eigenfrequency-analysis

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Henrik Sönnerlind
COMSOL
You need to enter the appropriate damping. You can find more information about structural damping in and > Also I started comparing the values from the eigenfrequency model, do you know how the results are defined for the eigenfrequency study? Which results are you referring to? For more information about eigenfrequency analysis, see also

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