So Abaqus uses some incremental formulation of nonlinear mechanics, right? This is not available in sfepy (and I have no experience with that). You probably cannot reformulate the update routine to the total Lagrangian formulation?

r.

On 07/09/2013 09:13 PM, Hadi Seyed Hosseini wrote:

Hi,

Thank you for your replies. Abaqus UMAT is in fact a material update routine providing an interface to implement the constitutive equations of a specific problem into the FE software Abaqus. In this subroutine, the inputs are strain tensor for the increment and the strain tensor for the beginning of the current increment, the deformation gradient tensor etc. The UMAT routine then updates the stress tensor and the corresponding material Jacobian for the end of the current increment at each integration point. The UMAT routine is normally written in Fortran.

In my case, I deal with a highly nonlinear elasto viscoplastic material behavior.

Best,

Hadi

On Monday, 8 July 2013 19:03:42 UTC+2, Hadi Seyed Hosseini wrote:

...

Hi,

I am quite new in the software and find it both useful and at the moment confusing. I have a user material (UMAT) written in Fortran for Abaqus and I would like to know if it is possible to wrap it into sfepy. As the software is highly object oriented, it is not easy to follow the existing examples, so that one can create a new problem and solve it using sfepy. All I need is to find out how to obtain the strain tensor or the deformation gradient tensor so that I can pass it to my material update routine to update the stresses and the material Jacobian tensors and at the end of the routine pass it to sfepy to calculate the force and the element Jacobian matrix.

I will appreciate any hint on this issue.

Thanks.

Hadi