On the relationship between normal load and friction force in pre-sliding frictional contacts. Part 2: Experimental investigation

When a tangential force is exerted on one of a pair of contacting bodies, the pre-sliding regime is traversed, before an object grossly slides. This paper is dedicated to the experimental investigation of the relation between the normal load and the friction force during the pre-sliding regime up to the point of sliding. For this purpose, a previously developed linear tribometer is used. A parametric model equation is constructed to fit adequately the measured hysteresis data. Thereafter, a parameter study is conducted to identify the influence of the normal load on the equation’s parameters. The results confirm the theoretical trend (presented in Part 1) that the coefficient of friction decreases, and the pre-sliding distances increases with increasing normal load, for a variety of contacting surfaces.