1, In motion study, when using solid body contact (with use precise contact in motion study properties setting), there are still the case the contact body penalty each other.

It does not happen each time, while it happened. Could someone give some advice on this, how to avoid this?

2, Using Restitution coefficient for the contact, there is no problem. However, when change it to material and Friction contact, the simulation will stop. What should I pay attention to if I change the way for the contact?

3, The advanced motion analysis options setting in motion study properties, what's the unit for the initial integrator step size?  Could someone give the general guideline for these setting?

Any advice will be appreciated.