Assign nonlinear material data for Composite using MAT8 with MATX25

Benjamin_20944

I perform a non-linear quasi-static analysis in OptiStruct where an impact element penetrates and expands a composite tube. This tube consists of 3 layers. Because each layer will fail at a different laod, I want to apply a stress-strain curve. This curve should fall on a low stress level (not zero) after the element fail.

It is possible to apply a stress-strain curve for MAT1 card. In my case I have to use MAT8 card where MATX25 makes ist possible to delete Elements after they fail. But if I delete them, the modell is not be consistent anymore.

Is there a possibility to use stress-strain curves for tension and compression in each laminate direction for a composite in OptiStruct? The elements should not be deleted after they failed and must still be able to take a certain amount of tension.

 

Thanks for help!

Regards

Benjamin

Adriano Koga_20259

Hi,

 

OS doesn't handle nonlinear material properties for composites directly.

MATX25 card s actually used in an old translation, where internally the model is converted to RADIOSS and then it uses RADIOSS nonlinear capabilities to run the job. So if you're using this approach, i would rather go directly to RADIOSS and define wheter you want eleemnt deletion or only stiffness loss.

 

Another alternative in your case, depending on your licenses, is to use MultiScale Designer. This tool allows you to create a more accurate material model to predict your material behavior, and then couple it with OptiStruct as a user material, quite easily. Then OptiStruct will run a nonlinear analysis for the macro deformations and MDS will carry out all the micro deformations and include changes in the fiber/matrix properties. I believe this would also be a nice piece in your model. If you take a look at MDS documentation you will find more examples.