1993 年 59 巻 563 号 p. 2116-2123
The performance of a tennis racket in terms of the coefficient of restitution (COR) is closely related to the impact phenomena. This paper investigates the effects of the frame vibrations on the coefficient of restitution and the contact time during the impact between a composed ball/string system and a simulated frame model using a FEM simulation and a modal analysis. The results show that the COR is mainly affected by a rigid motion and a bending vibration with two nodes of the racket frame. Results also show that the COR increases with an increase of frame stiffness, but it saturates at a certain stiffness depending on the impact velocity. Furthermore, the COR increases as the impact point comes as close as possible to the center of rotation and to the node of vibration of the racket frame.