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Inconsistency in Theory manual 6.0 and 6.2 - Multiplicative plasticity
Posted 2025年12月2日 GMT+8 22:25 Modeling Tools & Definitions, Structural Mechanics, Material Models Version 6.2 4 Replies
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Dear Community and Moderators,
I am seeking clarification on the flow rule for finite plastic strain with multiplicative decomposition. In COMSOL 6.0 documentation, the flow rule is:
and in COMSOL 6.2 documentation, the flow rule is:
I am confused about which one COMSOL actually uses. Or are they equivalent? Any help will be useful, thank you. Please see the attached screenshots as well.
-------------------Ratul Das
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Hello Ratul,
There was a typo in the 6.0 documentation, which was corrected by version 6.2.
Best regards,
Jeff
-------------------Jeff Hiller
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Dear Jeff,
Thank you for your message. I however did some hand calculations and I think the 6.0 documentation was correct (in multiplicative plasticity, the flow rule is written in terms of Kirchhoff stress). I can derive the equation written in COMSOL's equations page from that, please see the bracketed term in the attached screenshot image(4). If I use the equation from 6.2, I do not obtain the Jacobian J, in the beginning of the equation. Could you please elaborate or point me towards the correct reference it was taken from?
Thank you, Ratul
-------------------Ratul Das
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The latest version of the documentation (6.4) includes references, see this link. If this does not answer your question fully, I invite you to contact our tech support team.
Best regards,
Jeff
-------------------Jeff Hiller
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The latest version of the documentation (6.4) includes references, see this link. If this does not answer your question fully, I invite you to contact our tech support team.
Best regards,
Jeff
Thank you Jeff for sharing this. I will take a look.
-------------------Ratul Das
