Contribution of Hysteresis Component of Tire Rubber Friction on Stone Surfaces

This research examines the hysteresis friction of a sliding elastomer on various types of stone surfaces. The hysteresis friction is calculated with an analytical model that considers the energy spent by the local deformation of the rubber due to surface asperities of the stone surface. By establishing the fractal character of the stone surfaces, one can account for the contribution to rubber friction of stone roughness at different length scales. A high-resolution surface profilometer is used to calculate the three main surface descriptors and the minimal length scale that can contribute to hysteresis friction. The rubber is treated as a Zener visco-elastic material model. Modeling of the contact between the elastomer and the stone surface is based on the analytical model of Klüppel and Heinrich, which is a generalization of the Greenwood and Williamson theory of contact between spheres that are statistically distributed about a mean plane. The results show that this method can be used in order to characterize in an elegant manner the surface morphology of various stone surfaces and to quantify the friction coefficient of sliding rubber as a function of surface roughness, load, and speed.