Extract DDSDDE from Abaqus material model library

[tlesicar]

Me again...

I have a problem with extraction of DDSDDE. I would like to use Abaqus material model library and extract DDSDDE during analysis. I looked in documentation for possible subroutines, but there are not any except UMAT and UELMAT (in Standard) where I have to define my own material model and that is not want I want to... Is there any possible way to override this problem and extract DDSDDE without using UMAT???

Thanks!

[Jorgen]

I am not quite sure I understand what you are trying to do, but there is no official way to determine the DDSDDE matrix using built-in subroutines. It may be possible to do, but it certainly undocumented and probably not recommended.

-Jorgen

[tlesicar]

Thank You dr. Bergstrom on Your reply. I am doing some research on multiscale methods and I need tangent stiffness of every element. It would be quite useful to extract it from Abaqus without using UMAT and keep all Abaqus material models instead of programming my own. Do You have any hint or suggestion for some "undocumented way" of doing this? Or do You can recommend me some open source codes for metal plasticity, cyclic plasticity, etc...

Thank You!

[Frank]

*ELEMENT MATRIX OUTPUT
Write element stiffness matrices and mass matrices to a file.

This option is used to write element stiffness matrices and, if available, mass matrices to the results file, a user-defined file, or the data file.

only available in:
Product: Abaqus/Standard

[tlesicar]

Thanks on Your help, I solved the problem. But now I could use some UEL or UELMAT examples of plane strain element for geometric nonlinearity, or any code for nonlinear plane strain element.

Any suggestions?

[tlesicar]

Hi, it's me again.

I am wondering is there any other way for extracting DDSDDE from Abaqus without using UELMAT subroutine (which has subroutine for getting DDSDDE and STRESS). Programming nonlinear finite elements is quite a challenge... (at least for me).

Thanks for help!

[Jorgen]

I don't know of a simple way, except simply deriving the DDSDDE equations.

-Jorgen