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Solid, stress-strain module

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I am trying to estimate sagging for a membrane. The model is solved by COMSOL except at Poisson's ratio of 0.5, why??

2 Replies Last Post 2010年1月6日 GMT-5 17:11
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 2010年1月6日 GMT-5 16:48
Hi

Well if you ask yourself what the poisson coefficient does, I expect that you will see the reason why.

It gives the ratio, between the inline and out of plane deformations for a given linear strain.
Basically nu=0 would give a metrials behaving somewhat like a liquid, while nu=0.5 would be incompressible. your model will probably still solve for nu=0.495.

Well too simplified what I'm stating here but still not too far

Take a read of the doc from the structural chapter, you will find further clues there

Ivar
Hi Well if you ask yourself what the poisson coefficient does, I expect that you will see the reason why. It gives the ratio, between the inline and out of plane deformations for a given linear strain. Basically nu=0 would give a metrials behaving somewhat like a liquid, while nu=0.5 would be incompressible. your model will probably still solve for nu=0.495. Well too simplified what I'm stating here but still not too far Take a read of the doc from the structural chapter, you will find further clues there Ivar

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Posted: 1 decade ago 2010年1月6日 GMT-5 17:11
Thanks Ivar.

That was pretty lazy and stupid of me asking the question without bothering to read the basics of structural mechanics.

The material I am using is PDMS [(poly)dimethylsiloxane] for which nu=0.5; but I used nu=0.49, similar to what you suggested to get a fair idea of the sagging.

Thanks Ivar. That was pretty lazy and stupid of me asking the question without bothering to read the basics of structural mechanics. The material I am using is PDMS [(poly)dimethylsiloxane] for which nu=0.5; but I used nu=0.49, similar to what you suggested to get a fair idea of the sagging.

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