The effects of slip criterion and time on friction measurements

Different institutions reported different results for friction measurements of identical material combination and Surface conditions using identical slipmeters. The objective of this study was to evaluate three factors, slip criterion, sample, and time, that could contribute to such differences with two commonly used slipmeters, the Brungraber Mark 11 and the English XL. Friction between 16 commonly used footwear materials and three floor materials was measured under four surface conditions with two slip criteria at the interface. Some of the measurements were repeated it a different time. The results indicated that variations due to different samples were probably the smallest statistically among the three factors evaluated. The effect of slip criterion on friction coefficient could be quite significant compared with the effect of time for some material combinations and surface conditions. A more consistent slip criterion Could potentially reduce the differences significantly in the results reported among different institutions. (C) 2002 Elsevier Science Ltd. All rights reserved.