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error in evaluating variables

Posted Nov 12, 2015, 1:08 a.m. EST Structural Mechanics Version 4.4, Version 5.2 4 Replies

Greeshma Grace Paulson
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I am modelling a cantilever switch.while doing study i faced with an error of failed to evaluate variables and expression.
Failed to evaluate variable.
- Variable: comp1.emi.disp
- Geometry: 1
- Boundary: 22
Failed to evaluate expression.
- Expression: 1000000*comp1.emi.disp
- Plot: surf1 (Surface)
what does it mean?
4 Replies Last Post Dec 2, 2015, 12:56 a.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 9 years ago Nov 12, 2015, 2:29 a.m. EST
Hi

comp1.emi.disp is the displacement (sqrt(u^2+v^2+w^2)) of the Component comp1 (the first default model) of "emi" phyiscs Electromechanics from MEMS module. If you are in 2D w=0 and in 1D both v&w are =0, and in 2D-axi v=0.

But if your domain "1" is included in the EMI physics then "disp" should be defined. However, I suspect that you are plotting a complex geometry where only part of it is using EMI then "disp" is not defined everywhere. You must then restrict your Plot or Derived Value or Definition Variable to the domains where EMI is applicable

--
Good luck
Ivar
Hi comp1.emi.disp is the displacement (sqrt(u^2+v^2+w^2)) of the Component comp1 (the first default model) of "emi" phyiscs Electromechanics from MEMS module. If you are in 2D w=0 and in 1D both v&w are =0, and in 2D-axi v=0. But if your domain "1" is included in the EMI physics then "disp" should be defined. However, I suspect that you are plotting a complex geometry where only part of it is using EMI then "disp" is not defined everywhere. You must then restrict your Plot or Derived Value or Definition Variable to the domains where EMI is applicable -- Good luck Ivar
Greeshma Grace Paulson
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Posted: 9 years ago Nov 25, 2015, 2:15 a.m. EST
sir
thank you for your valuable reply. Here i am attaching my model. i couldnt follow your suggestion. i Humbly request you to help me for solving this issue
sir thank you for your valuable reply. Here i am attaching my model. i couldnt follow your suggestion. i Humbly request you to help me for solving this issue

Attachments:

Henrik Sönnerlind COMSOL Employee

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Posted: 9 years ago Nov 25, 2015, 4:41 a.m. EST
Hi,

Since none of the domains has the 'Linear Elastic Dielectric' material model, there are no displacement degrees of freedom in your model. All domains are purely electrical.

Regards,
Henrik
Hi, Since none of the domains has the 'Linear Elastic Dielectric' material model, there are no displacement degrees of freedom in your model. All domains are purely electrical. Regards, Henrik
Greeshma Grace Paulson
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Posted: 9 years ago Dec 2, 2015, 12:56 a.m. EST
Thank you sir for your reply.I got the displacement.
Thank you sir for your reply.I got the displacement.

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