Friction coefficient in ìrail ñ wheelî-contacts as a function of material and loading parameters

Processes occurring in a surface layer of solids in friction are simulated by the method of movable cellular automata (MCA). The model considered accounts for elastic and plastic deformations as well as detaching and iweldingi of wear particles. It is shown that relative movement of solids gives rise to a turbulent layer localized at the friction surface, in which intensive processes of mechanical mixing occur. We investigate the friction coefficient due to inelastic processes in the turbulent layer as a function of material parameters (yield stress, fracture stress, elastic moduli, viscosity, density) and loading parameters (sliding velocity and normal pressure). Numerical simulations show that the friction coefficient does depend only on two dimensionless combinations of the mentioned parameters. Loading conditions in real iwheel n raili contacts are analyzed and friction coefficient is calculated as a function of temperature.