Effect of loading condition on the traction coefficient between shoes and artificial turf surfaces

ASTM F2333 is a test method for quantifying traction characteristics between an athletic shoe and a sports surface. This standard calls for normal loads of 500-3000 N to be applied between a footform and a playing surface. To assess the effect of varying the normal load on the traction coefficients between cleated athletic shoes and artificial turf surfaces, a new testing device was developed and used to collect traction data. Four different models of cleated athletic shoes were tested on FieldTurf™ at normal loads ranging from 222 N to 1776 N. Static, dynamic, and peak traction coefficient values were calculated for each condition. There was a significant difference in the slope of the load versus traction coefficient curve for loads below and above 888 N for all three variables measured. No significant differences in traction characteristics were found between shoes for loads below 888 N. Significant differences between the shoes were seen with loads above 888 N. However, buckling and potential permanent damage to the turf surface were seen at loads of 1776 N. The results suggest that traction data obtained on FieldTurf at loads below one body weight are not sensitive to different shoe designs. Therefore, the measurement of traction between cleated shoes and FieldTurf should be conducted at a load of at least 888 N, which is, in part, consistent with the default normal load of 1000 N, in ASTM F2333. However, a normal force of 3000 N defined in the standard for studying stopping may not be feasible without permanently damaging the turf surface.