I have question:
in contact between 2 parts when we have defined surface behavior hard and friction in next step can we use parts with clearance or parts should have only gap = 0 or some interfrence ?
Contact status is tracked during the whole analysis and it can change between open and closed so you can have gaps. However, gaps typically lead to non-convergence due to rigid body motion in static analyses.
how to solve this problem in static analysis ?
It depends on the case but usually, the best way is to use prescribed displacement instead of force.