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Beam - Rigid Body

Posted Dec 20, 2016, 4:05 p.m. EST Version 3.5a 4 Replies

Gennaro Arguzzi
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Hi everyone. Is it possible to get a rigid beam?

Thank you for your help.

P.S. I'd like an infinite Young's modulus, not a finite Young's modulus.

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4 Replies Last Post Dec 21, 2016, 4:15 p.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 8 years ago Dec 21, 2016, 2:31 a.m. EST
Hi

I do not believe that was possible back in old 3.5 days ;)
Today with the newer versions there are the "Rigid Body" domains and the full RBD module to handle this.

--
Good luck
Ivar
Hi I do not believe that was possible back in old 3.5 days ;) Today with the newer versions there are the "Rigid Body" domains and the full RBD module to handle this. -- Good luck Ivar
Gennaro Arguzzi
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Posted: 8 years ago Dec 21, 2016, 3:02 a.m. EST
Hi Ivar,

in my university there is only the 3.5a version of Comsol, so I can't use next versions.

Regards,
GA.
Hi Ivar, in my university there is only the 3.5a version of Comsol, so I can't use next versions. Regards, GA.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 8 years ago Dec 21, 2016, 2:50 p.m. EST
Hello

Well back in 3.5 time, I used the trick you just said: turned up the Young modulus, to make my "rigid" parts real stiff.
But do not overdo it, 1000 to 10'000 times is already quite a lot, as else you might get numerical scaling issues. Note that eigenfrequencies scale as sqrt(E/rho) so these increase less than the Young modulus.

--
Good luck
Ivar
Hello Well back in 3.5 time, I used the trick you just said: turned up the Young modulus, to make my "rigid" parts real stiff. But do not overdo it, 1000 to 10'000 times is already quite a lot, as else you might get numerical scaling issues. Note that eigenfrequencies scale as sqrt(E/rho) so these increase less than the Young modulus. -- Good luck Ivar
Gennaro Arguzzi
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Posted: 8 years ago Dec 21, 2016, 4:15 p.m. EST
Hi Ivar,

I'd like to avoid the possibility of numerical issues. Is there another way to do it? The bigger Young's modulus, the bigger the possibility of numerical issues.

Thank you very much,
GA.
Hi Ivar, I'd like to avoid the possibility of numerical issues. Is there another way to do it? The bigger Young's modulus, the bigger the possibility of numerical issues. Thank you very much, GA.

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