Understanding the influence of surface roughness on the tribological interactions at the shoe–surface interface in tennis

Abstract

The traction provided by shoe–surface interactions in tennis can have an impact on player safety, performance and overall enjoyment of the sport. There is a requirement for an improved scientific understanding of the tribological interactions at the shoe–surface interface and the effects that footwear and surface characteristics have on the traction developed. The aim of this study was to investigate the influence surface roughness has on traction present during a sliding contact between a shoe and an acrylic hard court tennis surface. The substrate of acrylic hard court tennis surfaces are formed from a coating of a silica sand and acrylic paint mix, giving them variations in surface roughness characteristics. Mechanical traction tests were performed on five surfaces of varying roughness at normal forces of between 400 N and 800 N with a commercially available acrylic hard court tennis shoe (with a herringbone outsole pattern) and a shoe with a flat outsole. Significant linear relationships were found between dynamic traction force and normal force. A trend for decreased dynamic traction with increased roughness was found. When examined under a microscope after testing evidence of contact between the shoe and the surface decreasing with increased surface roughness was found. With the flat shoe, surface roughness affected the relationship between the coefficient of traction and the normal load. As roughness increased the coefficient of dynamic traction becomes less dependent on normal force. Evidence of a sudden increase in traction with the flat shoe when tested on the roughest surface suggests other friction mechanisms caused by the outsole overcoming the roughness of the surface, such as abrasive wear, had a significant effect on dynamic traction force.