59 巻 (1993) 566 号 p. 3108-3115
The performance of a tennis racket in terms of the coefficient of restitution (COR) is closely related to impact phenomena. The previous paper clarified that the COR is mainly affected by rigid motion and bending vibration with two nodes of the racket frame, and also that it increases as the impact point approaches the center of rotation and the node of racket vibration on the racket face. In this study, we investigate the effects of the frame mass distribution on the rebound velocity of a ball and the contact time during the impact between a composed ball/string system and a simulated frame model using a Finite-Element Method. We also consider the effects of the support condition of the racket and the racket swing by a player. Results show that the COR increases at the center and the top of a racket face with mass added to the top of the racket in spite of the decrease in preimpact racket velocity. Also, there is almost no difference in the coefficient of restitution and the contact time between a pin-jointed racket at the handle and a freely supported racket, and between the impact with a swing by a player and that without a swing.