A-24 Prediction and Estimation of Power of Tennis Racket ITF for ITF Performance Test

Several former top players sent a letter to the ITF (International Tennis federation) that tennis has become unbalanced and one-dimensional, because rackets today allow players to launch the ball at previously unthinkable speeds.Modern racket technology has developed powerful, light, wide-bodied rackets. There's even a racket with a chip built into the handle that allows the racket to stiffen upon impact with the ball. All of this technology has led to major changes in how the game is played at the top level. ITF seems to have started the test to examine the performance of tennis racket against the above claims. Since the sport should be learned from the experience, it is the subjective thing. Accordingly, it is quite difficult to see how the physical property of equipment has an effect on the performance of a player. The terms used in describing the performance of a tennis racket are still based on the feel of an experienced tester or a player even today. This paper investigated the physical properties of the racket that was manufactured by ITF for performance test, predicting its performance in terms of the coefficient of restitution, the rebound power coefficient, and the post-impact ball velocity relevant to the racket power. It is based on the experimental identification of the racket dynamics and the simple nonlinear impact analysis. The predicted results could explain the difference in mechanism of performance between the the racket ITF and the recent representative racket. The racket ITF provides higher coefficient of restitution particularly at the topside of string face and slightly higher post-impact velocity despite lower racket head speed compared to the recent representative racket. Prediction and estimation of feel will be reported in a separate paper.