A23 Prediction and Estimation of Shock Vibrations of Handled Tennis Racket with Biggest Sizes

The lightweight racket with head-heavy configuration is recent tendency of high-tech rackets, increasing power with an increasing racket swing speed. Racket frames as light as 200 grams have appeared in the market. However, the predicted results showed that the lightest racket at present in the market has advantageous for racket head speed, but disadvantageous for coefficient of restitution, rebound power, and post-impact velocity for ground stroke, and it has also large shock vibrations at the racket handle compared to the ordinary super-light weight racket. This means a limit to the weight lightening of tennis racket from the viewpoint of performance. The engineers and racket designers at the racket companies seem to be under intense pressure to keep pumping out new and better technologies every year. This paper investigated the physical properties of the biggest racket appeared in the market that was banned by ITF rules several years ago, predicting racket performance in terms of impact shock vibrations of player's wrist joint, which might be related to the feel. It is based on the experimental identification of the racket-arm dynamics and the simple nonlinear impact analysis. The result showed that the magnitude of shock vibration at the handle and the wrist joint with the biggest racket is rather small compared to the recent representative racket. Prediction and estimation of power will be reported in a separate paper.