My model has MPC contact with a moment applied at the pilot node. In version 9.0, the moment is transmitted to the rest of the structure. At 10.0, the moment seems to have no effect. Why did this behavior change?


The pilot node is getting auto-constrained in all DOFs at 10.0 -- this is a new defect. This bug in MPC contact has been fixed at 11.0.

However, please note that MPC pilot node DOFs will be auto-constrained in accordance with Sect. 3.9 of the 10.0 Contact Technology Guide. At 10.0, for this case, an applied Mx was incorrectly being resisted by an improper ROTX auto-constraint. In the fixed version, ROTX is now free. The other DOFs are still auto-constrained, per the documentation.

Note also that at 9.0, no pilot node DOFs were being auto-constrained. Because this behavior contradicted the documentation, the 9.0 behavior was considered to be erroneous.

As a result, many models having MPC contact will behave differently in versions 9.0, 10.0, and 11.0.





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