Hyperelastic anisotropic behavior law

Hello,

I'm currently doing my phd in biomechanics, and I need to implement hyperelastic anisotropic behavior law (like HGO model), i would like using the UMAT approach. I need the deformation gradient F for the anisotropic part, but the DFGRD0 in the UMAT interface is empty and i have read in the U2.10.01 manual that the DFGRD0 is not define in the interface. So I would like to know if there is another way to get the F tensor in the UMAT, or maybe another solution to access to this physical quantity for the implementation of a new behavior law.
Thanks in advance for your help

Best Regards
Jérémy

Hello Jérémy,
I'm no expert in material laws and didn't implement one myself, but as far as I know you should better try to use the Mfront interface rather than UMAT.

There should be some documentation on how to use it (you will need the latest development version 12.3):
- tfel.sourceforge.net/documentations.html

There are also some test cases available:
www.code-aster.org/V2/doc/default/fr/man_v/v1/v1.03.128.pdf or www.code-aster.org/V2/doc/default/en/man_v/v1/v1.03.126.pdf

Hope this helps.

Best regards,
Richard

Hello Richard,

Thank you for your help. I will see the Mfront solution and if it is possible to implement hyperelastic law by this way. Thank you for the documentation and the test cases.
Thank you


Best regards,
Jeremy