Rubber Friction and Tire Traction on Ice Surfaces: Physical Background and Predictive Testing

The understanding of mechanisms of rubber-ice friction is important for the design of tread compounds for winter tires. Ice is a particular surface, close to the melting point it has specific properties which have an impact on the friction, different to the usually expected friction between rubber and a solid like a dry or wet road surface. At temperatures just below 0°C, ice skid resistance is very low leading to low values of the friction‑slip behavior of slipping tires.

The presentation starts with an introduction into the topic of rubber friction and tire traction on ice surfaces. Main part of the presentation is devoted to the derivation and discussion of a simple laboratory predictor of tread rubber effects on tire traction on ice. The predictor is based on a simple physical model that contains the following basic assumptions: i) the ice surface is lubricated with a fluid layer; ii) a squeezed flow in the layer takes place where its internal viscocity is considered the major source of the frictional resistance on ice. The derived predictor can be easily correlated with data of the dynamic-mechanical analysis of the rubber. The linkage of the predictor to the complete viscoelastic mastercurve of the rubber is briefly explained. Furthermore, it is shown how a recently developed new physically based multi-scale approach for describing rubber mastercurves connects the lab predictor with typical relaxation times of the rubber polymers and rubber network.