Maybe someone can help me with this -- the only way that I have been able to run this study is with a global bonded contact and no contact sets specified. Once I add No Penetration contact sets, the model repeatedly fails. I've tried changing the mesh size, the time step, the connectors, and anything else that seems related, and have had no luck. I was wondering if anyone could give any insight, or maybe run the study to determine what direction I should take. Thank you for your time.
--Bryson
Hi Bryson,
I took a look at your model, and it's a little puzzling why it considers it unstable.
I did the following tests:
Bonded all contacts - Model started to solve
Added rotation lock to pins (with no penetration contact) - Model still unstable
Solids instead of shells (no penetration contact) - Model still unstable
Suppressed contacts where pins are used (ie pins are only load path) - Model started to solve
So I suppressed the pins and defined bolts with a little preload and it no longer complains of stiffness singularity at time zero. With the no penetration contact, the solve time is going to be lengthy, but I'll let it chug along and see the result.
I would not have expected the pins to be an issue. The only thing I didn't try was add mass to them. However I do not feel this is necessary as the pin is just coupling certain freedoms between the 2 shells and there is more than enough pins to sufficiently restrain the parts.
If you don't mind, I can pass this on to QA to check it out.
BTW, I'm trying it out on 2009 sp4.
Cheers,
Ian