Usermat ANSYS

[jaksonmv]

Hi,
I am a newbie in ANSYS and I have a doubt about the Jacobian Matrix and the strain and stress tensors used in the USERMAT routine.

In the numerical approximation of the Jacobian Matrix, the incremental strain that I have to use is a increment in the logarithmic strain tensor or in the right cauchy green tensor?
And... the increment in the stress tensor is a increment in the Kirchhoff stress tensor or in the Cauchy stress tensor?



I have developed a variational constitutive model and I would like to implement it in ANSYS. Anyone can help me?

Jakson

[Jorgen]

I believe it is the partial derivative of the increment in Kirchhoff stress with respect to the increment in logarithmic strain.

[jaksonmv]

Thanks Jorgen,

I will try in this way after that I compile with success my USERMAT routine, with the IMSL Fortran Library. (I posted this problem in another section of this forum)

Best regards,

Jakson