Abstract
Impacts of two spheres are generally characterized by coefficients of restitution. The coefficient of restitution is originally defined for the point mass while actual spheres have the size and deform in impact. This paper intends to discuss the effect of plastic deformation on the coefficient of restitution. The elastic plastic analyses of the impacts of two spheres are carried out for the various impact velocities by using the ANSYS code. The variations of the coefficients of restitution with the impact velocities are simulated. Then the coefficients of restitution are presented as the function of the impact velocities.