ERROR: THREE FACTORIZATIONS IN A ROW FAILED - Any Ideas?

[mbgm8ndb]

Hi All,
I have a large model that I imported from a NASTRAN BDF file and I am looking to get frequencies and mode shapes from a simple frequency analysis.
Because of the size of the model and the large run time for the whole model I have been deleting large numbers of elements using the mesh editor and applying suitable boundary conditions to isolate the areas of interest. This worked really well for 2 sections of the model, but when trying to look at a third I get the following error message:

***ERROR: THREE FACTORIZATIONS IN A ROW FAILED. CHECK THE MODEL. IT IS POSSIBLE THAT THE MODEL CONTAINS THE KINEMATIC COUPLING DEFINITION SET UP IN A WAY THAT A DEGREE OF FREEDOM HAS NEITHER MASS NOR STIFFNESS

Has anyone experienced this before and does anyone have any ideas what is causing this and how I can fix it? Thanks in advance for your help.

Regards,

Nigel

 

[TERIO]

My guess would be that when you were deleting elements from the mesh maybe an element or node was disconnected from the mesh.