Statev array in ABAQUS UHYPER subroutine.

[pantunes]

Hello!

I have one doubt! If you can help me...

The statev is an array containing the user-defined solution dependent variables. In a UHYPER subroutine do I have to define, the first deviatoric invariant BI1 as statev(1) and/or statev(2) as BI2? I'm asking that because I write a subroutine based on a compressible second order polynomial model and the subroutine works well in a unit dimension element without that variable assignment. In some ABAQUS examples that variable assignment is effectuated..
For instance, applying these two approaches in a Neo-Hookean model:
1) U = C10 * (BI1 - 3.)
2) U = C10 * (statev(1) - 3.)

Can you tell me what are the differences? If there is any....

Many thanks!!!

Paulo

[Jorgen]

There are some material models that have a dependence on only BI1, and there are some that have a dependence on both BI1 and BI2.

For a UHYPER subroutine all you need to specify is the partial derivatives of the strain energy density, similarly to your example.

If you still have problems, can you give a more specific example of what your are trying to do?

- Jorgen