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How to Define a nonlinear elasticity Model In Comsol 4.0?

Posted Apr 19, 2011, 2:26 a.m. EDT Fluid & Heat, Computational Fluid Dynamics (CFD) Version 5.0 7 Replies

Tao Haibing
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Dear Dr. Ivar,
I want to use a nonlinear Elastic relationship called "Duncan-Chang Model " for building a model about soil deformation. I use "Linear Elastic Material Model", and fill the parameters E and nu, of cause the E and nu, which now are fuctions about principal stresses (solid.sp1 and solid sp3). and it doesn't work with err "Circular variable dependency detected."
Are there some solutions that can be used to solve my problem ? and what technique need to be used in this problem?thanks a lot.
7 Replies Last Post Jun 7, 2016, 6:53 a.m. EDT
John Peterson
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Posted: 1 decade ago Apr 19, 2011, 3:26 p.m. EDT
Hi,
perhaps you could upload the equations you are trying to solve, so it would be easier to give you a hint.
best
john
Hi, perhaps you could upload the equations you are trying to solve, so it would be easier to give you a hint. best john
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago Apr 23, 2011, 12:06 a.m. EDT
You are getting this “circular variable dependency” because Young’s modulus is used to calculate stress, and you can’t make also a function of stress. If you can reformulate the equations to have Young’s modulus function of strain instead that should work.

Nagi Elabbasi
Veryst Engineering
You are getting this “circular variable dependency” because Young’s modulus is used to calculate stress, and you can’t make also a function of stress. If you can reformulate the equations to have Young’s modulus function of strain instead that should work. Nagi Elabbasi Veryst Engineering
Tao Haibing
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Posted: 1 decade ago Apr 24, 2011, 8:34 p.m. EDT
I know your meaning. In another word, it is the PDE that must to been used to solve this problem. Frankly speaking,I think the Structure module is not perfect and convenient now,
I know your meaning. In another word, it is the PDE that must to been used to solve this problem. Frankly speaking,I think the Structure module is not perfect and convenient now,
Cristian Cassella
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Posted: 1 decade ago Sep 9, 2011, 11:51 a.m. EDT
Hi,

about this discussion, if I have non linearities expressed in function of the stress how can I pass to a Young's module expressed as a function of the strain. Tks so much

Cristian


Hi, about this discussion, if I have non linearities expressed in function of the stress how can I pass to a Young's module expressed as a function of the strain. Tks so much Cristian
Tao Haibing
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Posted: 1 decade ago Jul 21, 2012, 10:21 a.m. EDT
After a year, finally i find the method to deal with use-defind nonlinear elasticity Model.
To avoid "Circular variable dependency detected." " problem it is best way to built anothor domain ODE.
thanks Nagi Elabbasi's advice, i didnt understand his words until today(one year later!!) god save me.
After a year, finally i find the method to deal with use-defind nonlinear elasticity Model. To avoid "Circular variable dependency detected." " problem it is best way to built anothor domain ODE. thanks Nagi Elabbasi's advice, i didnt understand his words until today(one year later!!) god save me.
剑华 邵
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Posted: 8 years ago Jun 7, 2016, 5:05 a.m. EDT
how to use Domain ODES to solve circular variable?Thank you!
my email:njutsjh@163.com
how to use Domain ODES to solve circular variable?Thank you! my email:njutsjh@163.com
Henrik Sönnerlind COMSOL Employee

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Posted: 8 years ago Jun 7, 2016, 6:53 a.m. EDT
Hi,

Here is an example:

www.comsol.com/model/modeling-stress-dependent-elasticity-14441

Regards,
Henrik
Hi, Here is an example: https://www.comsol.com/model/modeling-stress-dependent-elasticity-14441 Regards, Henrik

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