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Square wave signal driving a physical structure to get a sine frequency response

Posted 30 mars 2022, 21:19 UTC−4 MEMS & Nanotechnology, Structural & Acoustics, Studies & Solvers Version 6.0 2 Replies

John Reese
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Hi, I need some help applying a square wave signal on the MEMS scanning mirror to let it oscillate in its eigenfrequency. I create a analyse function of square wave and apply it to the terminal. But it seems I can't get its frequenct response by direct frequency domain analysis anyway. If I conduct a transient study, the time and space consumed are too large and I didn't get a result after even ten hours running. Is there a better way to do it or am I doing wrong? Thanks a lot.

2 Replies Last Post 31 mars 2022, 11:44 UTC−4
Henrik Sönnerlind COMSOL Employee

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Posted: 3 years ago 31 mars 2022, 02:33 UTC−4

The best method is to make a Fourier transform of the periodic forcing function, and then run a sequence of frequency response analyses.

You can find an example of this approach in the model Bracket – General Periodic Dynamic Analysis in Application Libraries. The model is also available in https://www.comsol.com/model/bracket-8212-structural-mechanics-tutorials-10314 as bracket_general_periodic.mph.

If you have a system with high Q factor and the pulse frequency coincides with an eigenfrequency, then only the first term in the Fouries series is needed.

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Henrik Sönnerlind
COMSOL
The best method is to make a Fourier transform of the periodic forcing function, and then run a sequence of frequency response analyses. You can find an example of this approach in the model Bracket – General Periodic Dynamic Analysis in Application Libraries. The model is also available in as bracket_general_periodic.mph. If you have a system with high Q factor and the pulse frequency coincides with an eigenfrequency, then only the first term in the Fouries series is needed.
John Reese
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Posted: 3 years ago 31 mars 2022, 11:44 UTC−4

Thank you so much for the reply. I would try it.

Best regards, John

Thank you so much for the reply. I would try it. Best regards, John

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