MAT9ORT Properties from Compositor

Altair Forum User

Hi,

 

I want to model a solid composite with MAT9ORT material.

As usual, getting all 9 material constants is pretty hard.

I want to model full unidirectional material like a pultrusion profile.

 

I have some material datas from compositor, which I inserted into the MAT9ORT card. (see attachment)

 

Optistruct stops with the error: 'Material coefficients Gij on MAT9 card produce material matrix with negative eigenvalues. This violates material stability conditions'

 

Does anybody know what's wrong with the material constants? What did I do wrong?  Inserted them wrong? Do I need more datas? Are there some simplifications?

 

Thank you!

 

 

<?xml version="1.0" encoding="UTF-8"?>

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Hi,

 

MAT9ORT is internally converted to MAT9 and calculations are performed using the MAT9. General guidelines for using MAT9ORT are provided in the OptiStruct user guide. Please refer to the same. 

 

If you think the numerical values you provided are correct, you can bypass the error using PARAM>>CHECKMAT>>NO. Please run the analysis with the same and check the results.