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Elasticity Matrix for Composite Materials

Posted 06.04.2020, 15:23 GMT-4 Structural & Acoustics, Materials, Results & Visualization 3 Replies

Denise Widdowson
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Hello,

I'm trying to find the effective material properties of a composite representative volume element. I've been trying to use periodicity or separate load cases and expect anisotropy in the resulting properties due to the geometry of the composite's constituents. However, when I solve the model for the load cases to populated the elasticity matrix, the resulting values are all the same for every component and every case. How is the elasticity matrix derived value calculated?

Thanks,

Denise

3 Replies Last Post 08.04.2020, 08:30 GMT-4
Pawan Soami COMSOL Employee

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Posted: 5 years ago 07.04.2020, 02:02 GMT-4

Dear Denise,

Please refer the following model from the Composite Application Library for the details.

https://www.comsol.com/model/micromechanics-and-stress-analysis-of-a-composite-cylinder-67001

Thi model exactly demonstrates what you are trying to achieve. Also use built-in Cell Periodicity node to compute the effective material properties instead of setting up the load cases manually for ease of modeling and to avoid any error in model set-up.

Best regards,
Pawan Soami

Dear Denise, Please refer the following model from the Composite Application Library for the details. https://www.comsol.com/model/micromechanics-and-stress-analysis-of-a-composite-cylinder-67001 Thi model exactly demonstrates what you are trying to achieve. Also use built-in Cell Periodicity node to compute the effective material properties instead of setting up the load cases manually for ease of modeling and to avoid any error in model set-up. Best regards, Pawan Soami
Denise Widdowson
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Posted: 5 years ago 07.04.2020, 11:55 GMT-4

Hello Pawan,

I have already reviewed that tutorial model. It seems that the anisotropy of the results stems from the orthotropic definition of the carbon fiber material. When the material is defined as isotropic the result breaks down. This theoretically should not happen as the geometry itself should drive an orthotropic composite elasticity matrix.

Thanks,

Denise

Hello Pawan, I have already reviewed that tutorial model. It seems that the anisotropy of the results stems from the orthotropic definition of the carbon fiber material. When the material is defined as isotropic the result breaks down. This theoretically should not happen as the geometry itself should drive an orthotropic composite elasticity matrix. Thanks, Denise
Pawan Soami COMSOL Employee

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Posted: 5 years ago 08.04.2020, 08:30 GMT-4

Dear Denise,

You are correct that even with isotropic material properties of constituents, the effective material properties should be orthotropic because of the geometry. This is what happens exactly if you replace carbon fiber material with any isotropic material say structural steel in the tutorial model. So I am not sure why you are not able to get the same results.

Feel free to contact support@comsol.com if you are not able to resolve the issue.

Best regards,
Pawan Soami

Dear Denise, You are correct that even with isotropic material properties of constituents, the effective material properties should be orthotropic because of the geometry. This is what happens exactly if you replace carbon fiber material with any isotropic material say structural steel in the tutorial model. So I am not sure why you are not able to get the same results. Feel free to contact support@comsol.com if you are not able to resolve the issue. Best regards, Pawan Soami

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