I hope everthing is alright in Aalborg!?
I have a question regarding the FDK: When I use the FDK inside a spherical joint in all 3 translational DoFs, why do I get in the joint constraints reaction still some force? These are small and neglectable (~10e-4 - 10e-3) but not numerical noise any more.
With the reactions switched off, the FDK solver will still leave a little reaction in the dof, but this reaction will always be less that the ForceTolerance setting of your study. The FDK solver tries to make it zero but only to level specified by the tolerance, this is equivalent to kinematic tolerances.