After further exploring the CBUSH element, I think it has to do with the orientation of the element not updating with the displacement of the nodes. This leads to incorrect results for large displacements.
Dear Sir/Madam,
I am modelling a system which contains a hinge. The hinge angle is related to the applied torque according to a hysteresis cycle, something like: Torque=k1*Angle+k2, where k1 and k2 are constants.
In particular, the torque vs angle relationship is as shown in blue in the figure...
Dear Sir/Madam,
The unit enforcement displacement and rotation valitidy check is a check described in the following link, in the FEMCI book:
https://femci.gsfc.nasa.gov/validitychecks/vc1.html
Basically, it consists on setting free all nodes of the model except one, which is given a unit...