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Modeling Magnetostriction - mod1.Azy variable

Posted Feb 25, 2016, 10:04 a.m. EST Low-Frequency Electromagnetics, Structural Mechanics Version 4.3 5 Replies

Hamid Shahrouzi
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Hello
I'm modeling magnetostriction in a laminated core in 2D. I have studied the '''non linear_magnetostriction'' model in COMSOL and have compare my model with that. In my model everything looks alright but the model does not run and returns the following error:

Fail to evaluate variable Jacobian.
- Variable: mod1.Azy
- Geometry: 1
- Domain: 2 ,5 , . . .
-Feature: stationary solver 1(sol1/s1)

Anybody has any comments?
Regards
Hamid
5 Replies Last Post Oct 3, 2016, 11:01 a.m. EDT
Hamid Shahrouzi
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Posted: 9 years ago Feb 25, 2016, 10:48 a.m. EST
Hi
I have to add a point. In fact this is very confusing for me that mod1.Az is a field component ( dependent variable) but this model was working before I add ''Solid Mechanics'' study.
Regards
Hamid
Hi I have to add a point. In fact this is very confusing for me that mod1.Az is a field component ( dependent variable) but this model was working before I add ''Solid Mechanics'' study. Regards Hamid
Nirmal Paudel COMSOL Employee

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Posted: 9 years ago Feb 26, 2016, 1:34 p.m. EST
Hi Hamid,

The Magnetic Fields physics is solved in the spatial frame (x,y,z i.e. non-solid) when there is no Solid Mechanics in the model. Therefore the spatial derivatives like. mod1.Azy i.e. derivative of Az with respect to y is available. However, if you solved Magnetic Fields together with the Solid Mechanics physics, the equations will be solved in the Material Frame (X,Y,Z i.e. Solid), the derivatives will be available as: mod1.AzY.

Hope this helps.

Best Regards,
Nirmal
Hi Hamid, The Magnetic Fields physics is solved in the spatial frame (x,y,z i.e. non-solid) when there is no Solid Mechanics in the model. Therefore the spatial derivatives like. mod1.Azy i.e. derivative of Az with respect to y is available. However, if you solved Magnetic Fields together with the Solid Mechanics physics, the equations will be solved in the Material Frame (X,Y,Z i.e. Solid), the derivatives will be available as: mod1.AzY. Hope this helps. Best Regards, Nirmal
Jeff Hiller COMSOL Employee

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Posted: 8 years ago Jul 1, 2016, 2:59 p.m. EDT
Of note in version 5.2a: new pre-implemented capabilities for modeling magnetostriction right out of the box in the Structural Mechanics Module: www.comsol.com/release/5.2a/structural-mechanics-module .
Best,
Jeff
Of note in version 5.2a: new pre-implemented capabilities for modeling magnetostriction right out of the box in the Structural Mechanics Module: https://www.comsol.com/release/5.2a/structural-mechanics-module . Best, Jeff
Hamid Shahrouzi
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Posted: 8 years ago Aug 19, 2016, 7:38 a.m. EDT
Hi Nirmal

I did not fully understand what you mean. Would you please clarify? I add and then disable the (solid) node in my model (in fact I'm not evaluating (solid) node at all) but after this, the model does not work anymore. What happens in the background and how can I fix it?

Best regards
Hamid
Hi Nirmal I did not fully understand what you mean. Would you please clarify? I add and then disable the (solid) node in my model (in fact I'm not evaluating (solid) node at all) but after this, the model does not work anymore. What happens in the background and how can I fix it? Best regards Hamid
Hamid Shahrouzi
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Posted: 8 years ago Oct 3, 2016, 11:01 a.m. EDT
COMSOL support solved this problem:
The error is caused by a conflict in the handling of frames. The physics
interfaces in Comsol can be usually solved either in a Solid material
("Material" frame) or in a Non-solid material ("Spatial" frame).
Electromagnetic interfaces are however an exception, since they require a
special treatment in presence of deformations (for example, Lorentz
currents must be added to moving conductors).
Therefore, in the current version, the electromagnetic interfaces require
that the "Material type" setting is consistent in all the features (either
Solid or Non-solid) and with the frame selected in the physics node.

In your model, it is sufficient to change the Material type in Ampère's
Law to Non-solid.
COMSOL support solved this problem: The error is caused by a conflict in the handling of frames. The physics interfaces in Comsol can be usually solved either in a Solid material ("Material" frame) or in a Non-solid material ("Spatial" frame). Electromagnetic interfaces are however an exception, since they require a special treatment in presence of deformations (for example, Lorentz currents must be added to moving conductors). Therefore, in the current version, the electromagnetic interfaces require that the "Material type" setting is consistent in all the features (either Solid or Non-solid) and with the frame selected in the physics node. In your model, it is sufficient to change the Material type in Ampère's Law to Non-solid.

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