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Maximum Displacement at Resonance frequency of cantilever beam Without any Load

Posted 04.06.2021, 05:17 GMT-4 Structural Mechanics Version 5.5 3 Replies

Khanjan Joshi
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Hey All,

I am working on a rectangular cantilever beam which is fixed at one end. I want to analyze maximum displacement at resonance frequency, in the situation when no load is applied but damping is added.

For this, I added geometry parameters and aluminum as material. I'm using solid mechanics as physics and in that I have defined Rayleigh damping and fixed constrain at one end. No load is applied to the cantilever.

I'm doing eigenfrequency study and by default surface displacement curve is plotted by COMSOL. In that curve eigenfrequency is coming proper (matched with hand written calculation) but total displacement at that eigenfrequency tends to zero.

1) what should I do to find maximum displacement at resonance frequency when no load applied to cantilever beam? 2) I have also tried loss factor damping but results are same as above so can anyone please tell me which damping should I add?

3 Replies Last Post 04.06.2021, 18:00 GMT-4
Edgar J. Kaiser Certified Consultant
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Posted: 3 years ago 04.06.2021, 05:59 GMT-4

Hm, why should the thing displace at all without any load?

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Hm, why should the thing displace at all without any load?
Khanjan Joshi
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Posted: 3 years ago 04.06.2021, 14:05 GMT-4

Hello Edgar,

Thanks for your quick reply.

My concern is to find Maximum peak overshoot (i.e. Mp= e^-[(pi*zeta)/sqrt(1-zeta^2)]) at resonance frequency (including damping) which will be inform of amplitude. can you suggest me some way for the same.

Hello Edgar, Thanks for your quick reply. My concern is to find Maximum peak overshoot (i.e. Mp= e^-[(pi*zeta)/sqrt(1-zeta^2)]) at resonance frequency (including damping) which will be inform of amplitude. can you suggest me some way for the same.
Edgar J. Kaiser Certified Consultant
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Posted: 3 years ago 04.06.2021, 18:00 GMT-4

You need to do a frequency domain scan around the eigenfrequency you found. You must apply a suitable load to the model in order to deflect it.

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
You need to do a frequency domain scan around the eigenfrequency you found. You must apply a suitable load to the model in order to deflect it.

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