SolidWorks Simulation 9 MATRIX_SINGULAR_OR_INDEFINITE

[Dravvy]

Hi guys,

I've attempted bumping an old thread as I imagine this problem occurs frequently but I could only find closed threads.

Early this year I ran a study to analyse the stresses within a quarter model of a cylinder head. It was an assembly drawing with five parts and the study ran fine.

I have since adapted the main body to be more complex and I can no longer run a study as this error occurs. It contains the same number of parts and I have checked that the loading and restraints are matching.

Any help would be much appreciated.

Thanks,Dan

 

[kellnerp]

This is a rudimentary problem. The matrix that the solver solves has to be positive definite. If it isn't you get this error.

A matrix will not be positive definite if the model is under constrained or has some badly formed elements (that have essentially zero stiffness) or if the model has more than one correct solution (buckling). So check your boundary conditions and your mesh and whether or not there might be buckling.

TOP
CSWP, BSSE

http://www.engtran.com

http://www.niswug.org

http://www.linkedin.com/in/engineeringtransport

"Node news is good news."

 

[Dravvy]

Thanks for the adivce,

After searching through my model I noticed that I had made a mistake when applying the fixtures on some of the parts.

A very silly, simple mistake.

Regards,
Dan

 

[kellnerp]

I say rudimentary because it has happened to me and hundred other poeple before.

Another good habit is to check the reactions on the model after a run. They are in a .out file somewhere. If your boundary conditions aren't right you can sometimes pick up a problem there. The units are in MKS AFAIK.

TOP
CSWP, BSSE

http://www.engtran.com

http://www.niswug.org

http://www.linkedin.com/in/engineeringtransport

"Node news is good news."