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Vibration of a cantilever beam

Posted Jan 17, 2013, 6:57 a.m. EST MEMS & Nanotechnology, MEMS & Piezoelectric Devices, Structural Mechanics Version 4.2a 3 Replies

Dhiman Mallick
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Hi,
I am trying to model a beam oscillating under external vibration condition.
I have kept one end of the beam fixed. I have tried applying different kind of boundary conditions to solve the problem.
1. applied accelaration (10m/s2) on the fixed end and did the freq domain analysis.
2. applied accelaration (10m/s2) on the entire structure and did the freq domain analysis.

but i did not get the expected displacement of the beam.

can anyone suggest what would be the appropiate boundary conditions and analysis method for such case?
3 Replies Last Post Jan 18, 2013, 1:52 a.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jan 17, 2013, 3:43 p.m. EST
Hi

the vibration load aspect is not trivial, you can either define a gravity = body force rho*a (a=acceleration) applying onto your model, with one boundary fixed, or add a "large Mass" object that can slide onto which you apply a force of given F=M*a with a the acceleration.

But the transfer functions are not exactly the same. Check the Forum, it has been discussed a few times
--
Good luck
Ivar
Hi the vibration load aspect is not trivial, you can either define a gravity = body force rho*a (a=acceleration) applying onto your model, with one boundary fixed, or add a "large Mass" object that can slide onto which you apply a force of given F=M*a with a the acceleration. But the transfer functions are not exactly the same. Check the Forum, it has been discussed a few times -- Good luck Ivar
Dhiman Mallick
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Posted: 1 decade ago Jan 17, 2013, 4:22 p.m. EST
Hi,
Thanks for your response.
I have indeed applied body load (i.e. g*acceleration). But my question is to get appropiate solution, what kind of study should I do? Should I apply the body load in the form of a sinusoid and do time dependent analysis with t defined for more than one time period (1/first eigen freq)? Is that correct or any other kind of simulation setup is needed?

Thanks in advance.
Hi, Thanks for your response. I have indeed applied body load (i.e. g*acceleration). But my question is to get appropiate solution, what kind of study should I do? Should I apply the body load in the form of a sinusoid and do time dependent analysis with t defined for more than one time period (1/first eigen freq)? Is that correct or any other kind of simulation setup is needed? Thanks in advance.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jan 18, 2013, 1:52 a.m. EST
Hi

I would propose harmonic development (frequency sweep swith a constant force amplitude (or a frequency dependet if you want to scan a PSD (power spectral density) distribution)

--
Good luck
Ivar
Hi I would propose harmonic development (frequency sweep swith a constant force amplitude (or a frequency dependet if you want to scan a PSD (power spectral density) distribution) -- Good luck Ivar

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