The first part of the question I do not understand, but second part about model impact contact: The general model for impact contact is by Energy spending on the surface
damage rate = 1/2 * m * V^2 where m - mass is the contact mass ( probably from experiment) v - velocity at the instant of impact ( also from experiment) you need a high speed camera focus at the instant of impact. May be you can read my publication at google, search my name kim pang
Dear Ganesh, you must disable the revolute joint first and then create a circle or a cylinder added to the first part with a selected radius R1, then create another circle or cylinder added to the other part with a radius R2 such as R2-R1 or R1-R2=clearance.
then create a contact : circle in circle or curve to curve or ... (