Learning Forum

[Jirong]

Hi All

I am using transient structural to do the simulation with Mooney-Rivlin material. I got error said "Matrix coefficient ratio exceeds 1.0e8, check results carefully." and then highly distorted element was reported. What should I do to reduce the matrix coefficient ratio and how can I extract it? 

 

In Analysis Settings, I turn on the large deflection, and use Damping for nonlinear control, and set stiffness coefficient to 1e-4 under damping controls.

 

I have used the same geometry with isotropic elasticity material before, it worked without matrix coefficient warning. Or is this because of my material ?

 

Thanks,

Jirong

[Sandeep Medikonda]

This warning message means stiffness matrix of the model is ill-conditioned. Some elements have severe differences in stiffness from other elements.

The ill-conditioned matrix can occur due multiple reasons such rigid body motion, highly distorted elements, high frictional contacts, units that may results in numbers too big/small, or even unstable material models.

Generally speaking about this message, it is just a warning and can typically be ignored.