Open questions on the impact of an inflated ball

TL;DR

This paper reviews the impact mechanics of inflated sports balls, focusing on energy dissipation sources, and proposes experiments to clarify the dominant mechanisms affecting ball behavior during impacts.

Contribution

It provides a comprehensive analysis of impact mechanics and introduces experimental approaches to identify the main energy dissipation sources in inflated balls.

Findings

Clarifies non-dissipative impact mechanics

Estimates various energy dissipation sources

Proposes experiments to determine dominant dissipation mechanisms

Abstract

The behaviour of sports balls during impact defines some special features of each sport. The velocity of the game, the accuracy of passes or shots, the control of the ball direction after impact, the risks of injury, are all set by the impact mechanics of the ball. For inflated sports balls, those characteristics are finely tuned by the ball inner pressure. As a consequence, inflation pressures are regulated for sports played with inflated balls. Despite a good understanding of ball elasticity, the source of energy dissipation for inflated balls remains controversial. We first give a clear view of non-dissipative impact mechanics. Second we review, analyse and estimate the different sources of energy dissipation of the multi-physics phenomena that occur during the impact. Finally, we propose several experiments to decide between gas compression, shell visco-elastic dissipation, solid friction, sound emission or shell vibrations as the major source of energy dissipation.