Negative Density Issue - Error 306076

[hortonc]

Last week we recieved a new material udb from the Moldflow lab. I have run three iterations on each of three parts I am working on and all of them fail due to negative density. The part sometimes goes two timesteps into the fill and fails and in one case went 10 hours in and then failed. 3D mesh quality is good, but when I view the fill data it looks like a mess. The surface nodes fill, but the center isn't, and when it is it often fills nodes that are not touching anything.

Out of curiosity I tried using a different material that is also proprietary and was characterized by the same lab and the fill worked perfectly. I am thinking the material data is wrong. Any help?

[raalteh]

Hi,

From what you are saying, I suspect the solver has problems converging, which is rare, but can happen for many reasons. The symptoms as you describe them are rare though. There

I would suggest you to:
1) Have a close look at the material data and confirm all the values in the material data are in the right order of magnitude.
2) Build a very simple test model (with few elements) and see if the problem is repeatable on that. If so, it is a good pointer to the material data being the source.
3) If the previous test does not produce the problem you saw, I would personally have a close look at the mesh, or remesh the model with a different (slightly smaller) edge length (to guarantee you produce a different mesh). Then try it again.


Regardless of the outcome, please contact your local support channel and ask them to have a look at this. Hopefully they can narrow down on the root cause, maybe with help of the development team.

Best regards,

Hanno