Rebound Property in Low Velocity Impact of Two Equivalent Balls

Abstract

The present study focuses on an impact phenomenon of two spheres and its rebound property. The collision of two spheres is a fundamental problem with impact phenomenon. The coefficient of restitution characterizes the property of impact phenomenon and has been estimated in general by experiment. In addition, it has been tried to estimate the coefficient by analytical and numerical methods. Considering body deformation, the body is deflected rapidly in collision and the strain rate occurred in the body is significantly high. It is well known the yield stress of the specific industrial material depends on the strain rate. However, it has not been proved the relationship between the coefficient of restitution and the strain rate in details yet. The present paper discusses the coefficient of restitution in low velocity impact of two equivalent balls. The impact experiments were conducted for the balls with different diameters by a pendulum impact apparatus. And the balls are numerically analyzed based on the finite element method considering the dependence of yield stress on strain rate as the material property of the balls. In conclusion, the strain rate decreases with the increment of the ball diameter and, it causes the coefficient of restitution to decrease.