Measure of relevance for modal/eigenfrequency analysis results

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When running an eigenfrequency analasys in comsol, I evaluate both the eigenfrequencies of the system, and the mass participation factors in the X, Y and Z translation, and X-axis, Y-axis, and Z-axis rotation direction.

In the end, I am just interested in which frequencies need to be further analyzed using Frequency Response Dynamic Analysis to see how they affect my system.

Is there a commonly used measure to summarize those six directional mass participation factor values into a single parameter that denotes the "relevance" of a certain frequency for further analysis?

As a possible idea: taking the mean or the root mean square (RMS) of the normalized mass participation factors in all directions?

Please see the attached image of frequency analasys results with an added column summarizing the information with a single measure, and highlighting via. conditional formatting (cell-color) which eigenfrequencies are relevant.



2 Replies Last Post 25 Oct 2020, 14:40 GMT-4
Henrik Sönnerlind COMSOL Employee

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Posted: 1 month ago 22 Oct 2020, 07:12 GMT-4
Updated: 1 month ago 22 Oct 2020, 10:35 GMT-4

Take a look at this example (which is also available in Application Libraries):

https://www.comsol.com/model/earthquake-analysis-of-a-building-65521

In it, there is a study step named Remove Low Mass Modes which implements one type of mode filter. You can create other similar filter expressions, for example based on an RMS.

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Henrik Sönnerlind
COMSOL
Take a look at this example (which is also available in Application Libraries): In it, there is a study step named *Remove Low Mass Modes* which implements one type of mode filter. You can create other similar filter expressions, for example based on an RMS.

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Posted: 1 month ago 25 Oct 2020, 14:40 GMT-4

@ Henrik Sönnerlind: Thank you very much for your response. This is very helpful.

@ Henrik Sönnerlind: Thank you very much for your response. This is very helpful.

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