Science of synthetic turf surfaces: Player–surface interactions

Abstract

During sports movements the cleats (also termed studs) penetrate and interlock with the playing surface generating traction forces. The ability to generate traction between a player's footwear and a sporting surface is a crucial factor influencing the player's performance as well as safety from lower limb injury. The traction produced for a given shoe–surface combination is dependent on a number of interacting factors operating at the interface, including the sport movement, the surface system composition, the footwear design and environmental conditions. Prediction and understanding of the mechanism providing traction has remained elusive. This paper presents experimental laboratory and field-based research conducted to assess the physical properties of third generation infilled synthetic turf surface components and the system's influence on the resulting measured rotational traction behaviour. Element testing of the crumb rubber infill was carried out to determine compressibility and shear strength. Systems were then constructed in the laboratory, altering aspects of carpet type, infill mass and density. The current industry standard equipment used to measure rotational traction in accordance with performance limits in soccer (i.e. FIFA) was utilized and also adapted to evaluate its suitability as a method for assessing rotational traction behaviour of synthetic turf surface systems. The results show the net bulk density of the infill layer can be a key controlling factor for the traction produced by the surface system as a whole. The net bulk density derived for the infill is shown to be dependent on a number of contributing factors, including the carpet type, infill size distribution, thickness of the infill layer, the level of compaction and the subsequent loading applied to the infill during testing. The stud configuration used was also shown to be a slight factor in system behaviour; however, the greatest effect on peak rotational traction resulted from changing the static normal force applied (i.e. static weight applied to the test device during a test).

Keywords:

• Traction
• equipment
• synthetic turf surface
• surface properties
• soccer