How to solve contact-pin problem?

[Bigtree]

Hi, I got this error while modeling circular pin-contact problem. How can it be solved?

Solver problem. Zero pivot when processing D.O.F. 1 of 1 nodes. The nodes have been identified in node set WarnNodeSolvProbZeroPiv_1_1_1_6_5.

Solver problem. Zero pivot when processing D.O.F. 1 of 1 nodes. The nodes have been identified in node set WarnNodeSolvProbZeroPiv_1_1_1_7_5.

Solver problem. Zero pivot when processing D.O.F. 1 of 1 nodes. The nodes have been identified in node set WarnNodeSolvProbZeroPiv_1_1_1_8_5.

Solver problem. Zero pivot when processing D.O.F. 1 of 1 nodes. The nodes have been identified in node set WarnNodeSolvProbZeroPiv_1_1_1_9_5.

 

[corus]

Part of the model is unrestrained

corus

 

[Bigtree]

Thanks. I will review my model.

 

[pooya1980]

If you are using a pin to model the analysis you should define the interaction between the pin and the other contact, but if you just defined the pressure applying from the pin to the contact , you should use nonelinear solver.
and make sure that your model doesn't revolve ( check your BC's)
POOYA

 

[Bigtree]

Thanks.
Error messages:
Time increment required is less than the minimum specified

I already used 1.E-6.

 

[corus]

If the model is continually cutting back on the time step then you may have chattering where one or two nodes are opening and closing each iteration. Check the msg file to see if this is the case. Use the contact controls option to fix this. If it's not this then you may still have a problem with restraints and something or other is just falling over.

I'm not sure why pooya suggests a non-linear solver for applying a pressure, or what that is. If you have any non-linearity in the problem such as large displacement or yielding then it's best to remove these to simplify the problem and to identify the source of the problem with contact. Add them back in later once the problem has been fixed.

corus

 

[Bigtree]

Hi, thanks.

 

[Bigtree]

Hi, the job is completed. How to plot analytical pin displacement v.s. applied load?