The effect of surface roughness and contaminant on the dynamic friction ofporcelain tile

Surface roughness affects friction, but it is not clear what surface roughn ess characteristics are better correlated with friction. The average of the maximum height above the mean line in each cut-off length (R-pm) and the a rithmetical average of surface slope Delta (n)) had the highest correlation with dynamic friction coefficient in a previous study. The previous study was expanded to two different footwear materials and four different contami nants on a porcelain tile in the current investigation. The results showed that dynamic friction decreased as the interface speed and glycerol content in the contaminant were increased due to the hydrodynamic lubrication effe ct. Delta (n) had the highest correlation with friction for most of the tes t conditions with neolite. For Four S rubber, friction coefficient appeared to have the highest correlation with the parameters related to the surface void volume at 30% glycerol content, related to the surface slope at 70 an d 85% glycerol contents, and related to the peak to valley distance at 99% glycerol content. A good indicator of surface slip resistance probably shou ld consist of the surface parameters representing the surface slope, the su rface void volume and the surface peak-to-valley distance with the coeffici ents determined by the system parameters. (C) 2001 Elsevier Science Ltd. Al l rights reserved.