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How can I use the variables in solid mechanics module as an input without causing circular reference

Posted 26 apr 2015, 21:20 GMT-4 Studies & Solvers, Structural Mechanics Version 4.4 3 Replies

Rong Xu
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Hi,

Recently, I want to consider the pressure induced temperature increase in solid mechanics module. This temperature will cause the thermal expansion. So in the thermal expansion part, the temperature would be a function of the pressure solid.pm. However, if I add the pressure solid.pm in the T define(because solid.pm is an output variable in solid mechanics module), the Comsol will show:
Circular variable dependency detected.
- Variable: comp1.solid.Sl11
- Geometry: 1
- Domain: 1
- Feature: Time-Dependent Solver 1 (sol1/t1)

So I want to know how to solve this problem. In previous discussion, I found some people said we can use different solver methods like 'Iteration' to avoid this circular reference. Is it right? How can I change the solver method? Thanks so much
3 Replies Last Post 25 mag 2015, 15:26 GMT-4
Nagi Elabbasi Facebook Reality Labs
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Posted: 9 years ago 27 apr 2015, 18:56 GMT-4
You can create a Domain ODE/DAE, with a single variable, say PP that you assign equal to the pressure, solid.pm. Then in the temperature definition refer to PP instead of solid.pm.

Nagi Elabbasi
Veryst Engineering
You can create a Domain ODE/DAE, with a single variable, say PP that you assign equal to the pressure, solid.pm. Then in the temperature definition refer to PP instead of solid.pm. Nagi Elabbasi Veryst Engineering
Rong Xu
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Posted: 9 years ago 27 apr 2015, 20:47 GMT-4
Hi,

Thanks for your advice. I think it would work well. I will try it right right!

Best,
Rong
Hi, Thanks for your advice. I think it would work well. I will try it right right! Best, Rong
Rong Xu
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Posted: 9 years ago 25 mag 2015, 15:26 GMT-4
Hi,

Last time you mentioned I can create a Domain ODE/DAE, with a single variable, say PP that you assign equal to the pressure, solid.pm. Now, in the Domain ODE/DAE, I set the source term as "PP-solid.pm" and set damping and mass coefficient as zero, as shown in Fig.
It seems there is a relatively large error between PP and solid.pm,especially at the boundary or interface. I am so confused about it. Did I miss something? Thanks!

Best,
Rong
Hi, Last time you mentioned I can create a Domain ODE/DAE, with a single variable, say PP that you assign equal to the pressure, solid.pm. Now, in the Domain ODE/DAE, I set the source term as "PP-solid.pm" and set damping and mass coefficient as zero, as shown in Fig. It seems there is a relatively large error between PP and solid.pm,especially at the boundary or interface. I am so confused about it. Did I miss something? Thanks! Best, Rong

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