MODELLING PREDICTIONS AND EXPERIMENTAL INVESTIGATIONS OF RUBBER FRICTION AND TIRE TRACTION

An advanced model of sliding friction and dynamic contact of elastomers on rough, self-affine surfaces is used for the prediction of rubber friction behaviour on dry granite. It describes the frictional force via the dissipated energy, resulting from sliding stochastic excitations of the rubber by surface asperities on various length scales [1, 2]. The effect of surface roughness is considered by three surface descriptors, which are derived from a fractal analysis of the surface profile obtained via white light interferometry. The hysteresis response of the rubber enters through viscoelastic master curves of the complex modulus up to high frequencies. Based on this concept, stationary friction curves have been estimated numerically on a broad velocity scale, in dependence of load and temperature. They have been compared to experimental friction data found for unfilled and filled elastomers under dry and wet conditions [3-13]. The obtained results allow for a deeper insight into the role of adhesion in dry friction of elastomers under different contact conditions [7-13]. In this work, the temperature and load dependence of the friction coefficient is analysed. We describe a relation between the required friction force and the applied load, as a function of temperature and velocity, whereby the extended friction theory of Kluppel and Heinrich [1] is included in the evaluation. It is found that the theory describes the experimental data fairly well. In addition, a closer look at the physical mechanisms that occur during sliding process is given.