Experimental Identification of a Hand-held Tennis Racket and Prediction of Racket Vibration during Impact.

Abstract

It is rather difficult to construct a theoretical model of the hand holding a tennis racket upon the interaction of a tennis ball with a racket. The coefficient of restitution during impact is supposed to be related to the main sources of energy loss caused by the collision such as the one due to the impact between a ball and strings, that due to the rotation of the racket and that due to the vibration of the racket frame. This study investigates the situation of a hand-held racket and the mechanism of impact, providing a simple impact model for estimation of coefficient of restitution of a hand-held racket on the basis of the idea that the contact duration is determined by the natural period of the entire system comprising the mass of a ball, the nonlinear stiffness of ball and strings, and the reduced mass of racket at the impact point on the string face. By applying the derived impact force and contact time to the experimentally identified vibration model of a hand-held racket, the vibration of racket during impact can be predicted. Further, the predicted restitution coefficient of a hand-held racket is compared with that of freely supported racket.