Abstract
This paper deals with the repeated impact between two identical spheres in which the strain rate dependency of the material has been considered. The experiments wens conducted by using steel balls (JIS SUJ2). Then the numerical simulations were earned out by using finite element analyses. The applicability of the prediction fbrthe coefficient of restitution proposed by Graham was examined for the case of this study. It was found that the coefficient of restitution increased with the inpact number and the contact duration decreased with the impact number. The expression for the coefficient of restitution proposed by Graham gives the valid results only if the initial coefficient of restitution was given accurately.
