Nagativ eigenvalues in matrix 2

[Engelien01]

I get two warning massages:

1. Strain output request le is not valid for some elements in this analysis. The request is switched to the strain measure, e. and

2. The system matrix has ... negativ eingenvalues.

and the job stops with the Error "too many attempts for an increment".

What is the reason of the strain putput request?

Thanks

 

[CalPolyME2005]

If you have nonlinear geometry enabled, the default strain output request is LE (logarithmic strain measure). However, this strain measure is not available for some elements, like beams. The warning is issued to let you know that the strain output request is being changed by the software. It should not affect the convergence of the solution.

 

[gurmeet2003]

Engelien01,

Negative eigenvalues usually mean not enough constraints leading to rigid body motion.

Gurmeet

 

[Engelien01]

Thanks for the help! Both were helpful to solve same negativ eigenvalues, but I still have one and I have really no idea how to fix them...

 

[Engelien01]

now I have no warnings anymore..

But Error "too many attemps for an increment" *grr*

 

[xerf]

You could try to reduce the initial/minimum and maximum time increments for the step causing the error.