Large Deflections during Bounce of Inflated Balls

Abstract

Dynamic analyses for impact of sports balls almost exclusively are based upon rigid-body dynamics. At impact speeds representative of ball games, this paper obtains effects of finite deflections and a finite contact area on the changes in velocity and angular velocity of a thin-walled, inflated ball. Momentum flux associated with the evolving contact region is shown to be non-conservative and a significant source of energy dissipation during impact of thin-walled balls against a court surface. Nevertheless, changes in both angular speed of the ball and direction of bounce are modest for coefficients of friction that are representative of sports surfaces.

This paper obtains results from a large deflection theory that calculates changes of bounce that result from the finite contact area that develops during impact. These changes in rate-of-spin and rebound velocity of basketballs, soccer balls, ect are related to the structure and material properties of inflated thin-walled spherical balls.