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Moddeling change in resistance/conductance due to thermal expansion

Posted 26 juin 2014, 05:07 UTC−4 Low-Frequency Electromagnetics, Geometry, Mesh, Structural Mechanics Version 4.4 5 Replies

Rutger Stottelaar
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Dear Comsol users,

Due to temperature a material expands and when it does the electrical resistance of this material also changes. I want to model this in comsol.

I added the thermal expansion first, this gives results and the deformations can also be seen. Afterwards I want to calculate the resistance of this deformed structure and that is where it goes wrong. I cannot get different resistance values of different deformed structures.

I tried to add ALE afterwards but this does not seem to generate any results.

The model I attached is a very simplified model of what I am trying to create. However this is just to find out how the physics work in Comsol.

many thanks in advance for the help

Attachments:

5 Replies Last Post 30 juin 2014, 05:41 UTC−4
Pieter Westerik
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Posted: 1 decade ago 27 juin 2014, 03:42 UTC−4
Hi Rutger,

As far as I know, resistance changes caused by deformation are usually due to geometry changes rather than material properties changes. For exampe a strain gauge that is stretched becomes longer and, by the Poisson ratio, thinner, and by resistance = resistivity * length / {cross sectional area}, you find that the resistance increases, while the material propery (resistivity) remains the same.
Hi Rutger, As far as I know, resistance changes caused by deformation are usually due to geometry changes rather than material properties changes. For exampe a strain gauge that is stretched becomes longer and, by the Poisson ratio, thinner, and by resistance = resistivity * length / {cross sectional area}, you find that the resistance increases, while the material propery (resistivity) remains the same.
Rutger Stottelaar
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Posted: 1 decade ago 27 juin 2014, 03:58 UTC−4
Dear Pieter,

You are correct. I formulated my sentence incorrectly.

Due to the expansion of the material the resistance of the geometry will increase. However, how do I model this in Comsol?
Dear Pieter, You are correct. I formulated my sentence incorrectly. Due to the expansion of the material the resistance of the geometry will increase. However, how do I model this in Comsol?
Pieter Westerik
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Posted: 1 decade ago 27 juin 2014, 04:13 UTC−4
Sorry, I don't know.
Sorry, I don't know.
Henrik Sönnerlind COMSOL Employee

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Posted: 1 decade ago 27 juin 2014, 07:29 UTC−4
Hi Rutger,

You do not need to add an ALE interface. You just have to switch on 'Include geometric nonlinearity' for the study step. Then the Electric Currents will see the deformed frame.

Regards,
Henrik
Hi Rutger, You do not need to add an ALE interface. You just have to switch on 'Include geometric nonlinearity' for the study step. Then the Electric Currents will see the deformed frame. Regards, Henrik
Rutger Stottelaar
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Posted: 1 decade ago 30 juin 2014, 05:41 UTC−4
Dear Henrik,

Thank you for the advice, it seems to work!

Rutger
Dear Henrik, Thank you for the advice, it seems to work! Rutger

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