Erik Kostson
Ansys Employee
Without looking at the model it is hard to say, but very likely there could be a rigid body motion of some parts.

Perhaps, the contact between the two cylinder halves, and the bottom cylinder is probably not active (assuming there a contact there defined) since there is a large gap between as far as we can see - so move these parts together so they just touch and assign initially a bonded contact between these parts. ALso make sure the contact between bolts and their different parts they connect to are there. Finally we need at least one fixed support say (which there is), and also switch off the material nonlinearities (set Nonlinear Effects to No for all parts). So try those things and let us know how it goes.

All the best