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Force between to two closing magnets

Posted 21 mar 2011, 15:26 GMT-4 Low-Frequency Electromagnetics, Geometry, Materials, Parameters, Variables, & Functions, Structural Mechanics Version 4.0a 3 Replies

Jiewen Deng
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Hi everyone,

I just began using Comsol to do some simulations, and my question is that:

Right now I have two cylindrical N42 magnets, the thickness is 5mm, and the diameter is 15mm, the distance between them is 50mm initial, and the distance decreases gradually with a step 1mm. I need to find out the attractive force between the two magnets in the different distances, does anyone have any idea about how can I input the model?

Furthermore, I attach one of the magnet at the end of a cantilever beam, and the other one is attached on a roof which is vertically placed with the one on the beam. An external vibration is loaded on the fixed end of the cantilever beam, how can I get the displacements of the free end of the beam?

Thank you very much!
3 Replies Last Post 30 mar 2011, 15:09 GMT-4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 22 mar 2011, 02:39 GMT-4
Hi

you have many questions, most of them you should be able to answer yourself if you had started simpler with one physics. Try it out, solve only for the cantilever beam and identify the forces, and displacements (u,v...), then do the magnetic part, alone, identify how to calculate forces, then finally mix both. Its much quicker, and less frustrating

--
Good luck
Ivar
Hi you have many questions, most of them you should be able to answer yourself if you had started simpler with one physics. Try it out, solve only for the cantilever beam and identify the forces, and displacements (u,v...), then do the magnetic part, alone, identify how to calculate forces, then finally mix both. Its much quicker, and less frustrating -- Good luck Ivar
Jiewen Deng
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Posted: 1 decade ago 30 mar 2011, 14:17 GMT-4
Hello, Ivar,

I have done some simulations these days. Right now I need to add a constant acceleration to the fixed end of the cantilever beam, and the input frequency increases from 1 Hz to 100 Hz. Have you any ideas about how can load this constant acceleration with increasing frequency?

Thank you

Jiewen
Hello, Ivar, I have done some simulations these days. Right now I need to add a constant acceleration to the fixed end of the cantilever beam, and the input frequency increases from 1 Hz to 100 Hz. Have you any ideas about how can load this constant acceleration with increasing frequency? Thank you Jiewen
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 30 mar 2011, 15:09 GMT-4
Hi

I'm not sure fuunderstand what you are doing, but if you are infrequency domain with a harmonic development, for a displacement amplitude (0-pk) of "u", the velocity amplitude is "2*pi*freq*u" and the acceleration amplitude is "(2*pi*freq)^2*u" so to keep it constant with the frequency it should be enough to tweak the acceleration amplitude formula a little, no ?

--
Good luck
Ivar
Hi I'm not sure fuunderstand what you are doing, but if you are infrequency domain with a harmonic development, for a displacement amplitude (0-pk) of "u", the velocity amplitude is "2*pi*freq*u" and the acceleration amplitude is "(2*pi*freq)^2*u" so to keep it constant with the frequency it should be enough to tweak the acceleration amplitude formula a little, no ? -- Good luck Ivar

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