Flexible beam analysis of the effects of string tension and frame stiffness on racket performance

Abstract

It is generally accepted that a decrease in string tension leads to greater racket power and an increase in tension improves racket control. The increase in power at low string tension can be attributed partly to a decrease in energy loss in the ball and partly to a decrease in the vibrational energy transferred to the racket. Racket control is affected if the ball strikes the strings towards one edge of the frame, in which case the racket will rotate about the long axis through the handle. The angle of rotation is decreased when the string tension is increased. Quantitative estimates of the magnitude of these effects are presented, using a one dimensional flexible beam model to describe the racket and springs to model the ball and strings. For tensions in the range 50–60 lb (220–270 N), commonly used in tennis rackets, and for a ball incident at right angles to the string plane, changes in racket power and control are essentially negligible. However, a significant increase in racket power can be achieved by increasing the stiffness of the racket frame.