The effect of contact area on friction measured with the portable inclinable articulated strut slip tester (PIAST)
AbstractA portable inclinable articulated strut slip tester (PIAST) measures friction at the shoe and floor interface. The squeeze-film effect with the PIAST is excessive in representing a human strike. The goal of this study was to investigate the effect of the contact area size on friction for reducing the squeeze-film effect. The footwear pad area of this slip meter was sequentially reduced from 7.62 cm square to 2.54 cm square. Five walkways were constructed. Friction was measured on each walkway under three surface conditions. Thirty-five participants rated their perceptions of slipperiness. The results indicated that the friction increased and plateaued as the size of the contact area was reduced. The effect of the pad size on the friction coefficient was statistically significant. The correlation coefficients between the friction and perception rating did not give a clear indication of what pad size might have a better correlation with human perception. Friction measurement at the shoe and floor interface is a critical issue in assessing potential interventions and identifying potentially dangerous locations for slip and fall incidents. This paper addresses a potential improvement in measuring friction on liquid-contaminated floor surfaces.