An investigation of the comparative behaviour of alternative contact force models during inelastic collisions

Rebound kinematics are compared for both viscous dissipation and plastic dissipation models for an inelastic sphere obliquely impacting a target wall for a range of normal coefficients of restitution. The models are quite consistent for high normal coefficients of restitution but significant differences are noted between the models as the normal coefficient of restitution reduces. The reasons for the differences, in terms of the rebound tangential surface velocities, are explained for both plastic and viscous dissipation models. A new ‘partially latching spring’ model is proposed that provides realistic predictions of the contact force magnitude and contact duration. Finally, a general condition for sliding to occur throughout inelastic impacts is identified for any value of the normal coefficient of restitution.