Time dependent material properties and material stability conditions

Rahul_P1

Hello,
I have problems creating an model.
The model includes an pretensioned Bold that applies preassure onto an orthotropic material.
Therefor I have jused the Pretension Manager in Optistruct and the card image MAT9ORT for the material.
Now I have two problems.

The first problem is, that the material properties of the orthotropic material are time dependant and I have no clue how to incorporate this into my model.

The second problem is with the material stability conditions, I do not see any possibility to fix this without changing the material properties, but those are, naturally fixed:

*** ERROR # 1551 ***
for material id = 2 referenced from property id = 1.
Material coefficients Gij on MAT9 card produce material matrix with negative
eigenvalues. This violates material stability conditions.
Eigenvalues of G: -8.915074E+02 1.565340E+01 9.060199E+00
3.612000E+00 2.535000E+00 3.612000E+00

Rahul_P1

Hello,

to give a quick reply on this:
- Currently there is no way to define MAT9ORT as a time dependent material. Only Frequency and Temperature Dependance can be applied.
- This is due to the fact that you are running a quasi-static analysis where time is not a factor. To see time-effects you might need to change to Radioss Solver (explicit or implicit non-linear)
- To avoid the material check you can activate the parameter MATCHECK NO as indicated in the error message. To do so, please go to Setup -> Control Cards -> Param within HyperMesh
- It might be an alternative to check the interdependancy between your entered MAT9ORT values using the comments in the OptiStruct Solver help and adapt your values to be aligned with the composite material law.

With kind Regards
Jan