The coefficient of restitution of pressurized balls: a mechanistic model
Abstract
Pressurized, inflated balls used in professional sports are regulated so that their behaviour upon impact can be anticipated and allow the game to have its distinctive character. However, the dynamics governing the impacts of such balls, even on stationary hard surfaces, can be extremely complex. The energy transformations, which arise from the compression of the gas within the ball and from the shear forces associated with the deformation of the wall, are examined in this paper. We develop a simple mechanistic model of the dependence of the coefficient of restitution, e, upon both the gauge pressure, P_G, of the gas and the shear modulus, G, of the wall. The model is validated using the results from a simple series of experiments using three different sports balls. The fits to the data are extremely good for P_G > 25 kPa and consistent values are obtained for the value of G for the wall material. As far as the authors can tell, this simple, mechanistic model of the pressure dependence of the coefficient of restitution is the first in the literature. *%K Coefficient of Restitution, Dynamics, Inflated Balls, Pressure, Impact Model
 Publication:

Canadian Journal of Physics
 Pub Date:
 January 2016
 DOI:
 10.1139/cjp20150378
 Bibcode:
 2016CaJPh..94...42G
 Keywords:

 Coefficient of Restitution;
 Dynamics;
 Inflated Balls;
 Pressure;
 Impact Model