I did a static non linear simulation of a spur gear in order to evaluate the mesh stiffness. I am using CCX 2.17. To do that I created a rigid body to the hub of the pinion and the wheel. The simulation has 4 steps:

imposed rotation on the pinion to initialize the contact (keeping wheel fixed)

Impose a small torque on the wheel (keeping pinion fixed)

Impose the desired torque on the wheel (keeping pinion fixed)

Impose the desired resisting torque on the wheel and impose a rotation on the pinion corresponding to 2 mesh cycles.
A surface to surface penalty contact without friction is used, everything converges and the results are (apparently) similar to previous works. The problem relies on the results of Reaction Force (RF) for the rotation nodes used for the rigid body (step 4):
 the reference nodes donâ€™t belong to the node set;
 the imposed torque is correct on the wheel;
 the imposed rotation is correct on the by pinion;
 but the torque evaluated on the pinion rotation node is not constant and also depends on the penalty coefficient. I expected to have influence on the rotation angles onlyâ€¦
It would be helpful to have your feedback. My experience with CalculiX is mostly doing thermal analysis of gears, so probably I am missing some important points.
Best regards,
Carlos Fernandes