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Rubber material model in Structural Mechanics

Posted 08.11.2017, 21:17 GMT-5 3 Replies

Richard Anderson
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I have modeled a rubber with hyperelastic material and then fitted experimental uniaxial tensile data with Mooney Rivlin method. As rubbers are nearly incompressive materials, do I need to import compressive test data too? In fact , I want to stretch the rubber and       then release it. So, in this case, do I need the uniaxial compressive stress-strain curve to model the releasing mechanism?

3 Replies Last Post 16.01.2018, 08:05 GMT-5
Henrik Sönnerlind COMSOL Employee

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Posted: 7 years ago 09.11.2017, 13:40 GMT-5

Hi,

If you stretch and release an (hyper)elastic material you follow the same path. If you move to compression, then the tensile test may not be sufficient.

A triaxial compression test is meningless because of the incompressibility, while a unixial compressive test is important. You can compress rubber a lot along one axis, it only expands in the two other directions to maintain its volume.

I think the discussion in this blog post might be of interest:

https://www.comsol.com/blogs/obtaining-material-data-for-structural-mechanics-from-measurements/

Regards,

Henrik

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Henrik Sönnerlind
COMSOL
Hi, If you stretch and release an (hyper)elastic material you follow the same path. If you move to compression, then the tensile test may not be sufficient. A triaxial compression test is meningless because of the incompressibility, while a unixial compressive test is important. You can compress rubber a lot along one axis, it only expands in the two other directions to maintain its volume. I think the discussion in this blog post might be of interest: https://www.comsol.com/blogs/obtaining-material-data-for-structural-mechanics-from-measurements/ Regards, Henrik
Richard Anderson
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Posted: 7 years ago 09.11.2017, 14:18 GMT-5

Dear Henrik Thank you very much for clarification.. In fact, I want to stretch a rubber from both ends to achieve a specific strain, then Im going to pattern     or attach a ribbon on the top of the stretched rubber. Finally, Im going to release the rubber to its original size. I dont know how to implement this mechanism. Actually I cant understand how to join an unstrained object ( in my case, the ribbon) to a prestrained object( rubber) Could you please help me? Best,

Dear Henrik Thank you very much for clarification.. In fact, I want to stretch a rubber from both ends to achieve a specific strain, then Im going to pattern     or attach a ribbon on the top of the stretched rubber. Finally, Im going to release the rubber to its original size. I dont know how to implement this mechanism. Actually I cant understand how to join an unstrained object ( in my case, the ribbon) to a prestrained object( rubber) Could you please help me? Best,
Asad Nauman
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Posted: 7 years ago 16.01.2018, 08:05 GMT-5

Hello Richard Anderson, Have you solved the problem of stretching the rubber from the ends. I also want to do the same, but with the fixed constraints it is not possible and I don't want to fix the constrains. I am using PDMS as stretchable material and want to stretch from both the ends.

Regards, Asad Nauman

Hello Richard Anderson, Have you solved the problem of stretching the rubber from the ends. I also want to do the same, but with the fixed constraints it is not possible and I don't want to fix the constrains. I am using PDMS as stretchable material and want to stretch from both the ends. Regards, Asad Nauman

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