Traction of studded boots on turf

The traction force of studded boots on artificial turf was studied using a friction sled pulled by a constant speed motor. The traction of 6 and 12 mm cylindrical studs were studied on an artificial surface with grass fibre lengths of 50mm and filled with rubber crumb and sand. It was found that the traction force increased with the number of studs and became approximately constant if more than six studs were used. Doubling the stud length more than doubled the traction. A simple model of traction was developed, in which the total traction was equal to the plate friction plus the ploughing traction of studs. The ploughing traction increased and the plate friction decreased with the number of studs, due to lift that was generated by each stud as the sled moved across the surface. The theory over predicted the traction for large numbers of studs, probably because leading studs shielded following studs, thus reducing the shear strength of the surface.