ABSTRACT

A fully developed slip condition may require the determination of steady-state kinetic friction, which is produced only after some time-delay from the slip start, whilst the static friction is limited to the slip start before any detectable motion. The transitional behaviour of the coefficient of friction between those two extremes has evoked little interest, though some of the current test instruments may measure that property (Grönqvist, 1997). The transitional period after the slip initiation is typically very short (less than 250 ms) when slipping at heel touch-down, and it seems to reflect well the squeeze-film phenomena during early stance foot slip-ups on contaminated surfaces.