Simulation of the Impact of Two-Dimensional Elastic Disks
  The impact of a two-dimensional elastic disk with a wall is numerically studied. It is clarified that the coefficient of restitution (COR) decreases with the impact velocity. The result is not consistent with the recent quasi-static theory of inelastic collisions even for very slow impact. The abrupt drop of COR has been found due to the plastic deformation of the disk, which is assisted by the initial internal motion. (to be published in Proceedings of 9 th Nisshin Engineering Particle Technology International Symposium on 'Solids Flow Mechanics and Their Applications' held at Kyoto, 7th-9th January, 2001 
Hisao Hayakawa and Hiroto Kuninaka