Advanced viscous model for viscous friction between rough rubber and smooth ice

In the tire industry, the phenomenological comprehension of the contact between the tire and the road is one of the most important aspect in order to improve the tractive performance of the vehicle, in particular in winter condition. The rubber-ice frictional behaviour is characterized by a series of complex physical phenomena. During the sliding-contact between the rubber of the tire and the ice, the frictional heat leads to the melting of the ice. The amount of the water created during the ice melting involves hydrodynamic effects and the need to use a viscous formulation to describe the interaction between the two objects. Consequently, the friction coefficient between the rubber and the ice is non-stationary. The numerical simulation of the contact between these two materials is a challenging problem. This is mainly due to the high values of the rubber deformation as well as the significant difference of the stiffness between these two materials. In this overview, in this work the contact between a sliding rubber block and the ice was simulated. Both the thermodynamic and the hydrodynamic phenomena, as well as the phase change of the ice were considered in the model. The model was based on a contact theory proposed in the literature. To this aim, a specific subroutine was developed. . The subroutine works in parallel with a standard contact algorithm. The subroutine works starting from the current values of the thermo-mechanical parameters e.g. the interface pressure, the nodal temperature and the sliding velocity. The model governed by the subroutine gives as output, step by step, the current value of the friction coefficient. The close interaction between the two modules implies that, a variation of the thermo-mechanical phenomena affects also the contact friction and vice-versa. The comparison between the friction coefficient obtained with the numerical simulation and the coefficient obtained with the analytical solution proposed in the literature, showed good correlation. The accuracy of the developed numerical model was also confirmed by the comparison between the numerical results and some experimental results that can be found in the literature. The numerical model of the rubber-ice contact developed in this works is the base for the simulation of a full tire model rolling on an icy road.