Numerical Investigations Into the Effects of Oil Contamination and Surface Roughness on Wheel-Rail Adhesion

A numerical model is developed to estimate the adhesion coefficient, namely the maximum coefficient in the rolling direction between wheel and rail under oil contamination. In the model, the partial elastohytrodynamic lubrication (EHL) theory and Newton-Raphson method are used. The pressure distributions of hydrodynamic and asperities contact between wheel and rail with high speed are obtained. Effects of rolling speed, slip ratio and parameter of roughness orientation on adhesion coefficient are also discussed. The results show that the rolling speed greatly influences the adhesion coefficient under oil contamination. When the speed increases, the adhesion coefficient decreases rapidly. A qualitative description is used to explain the reason of such decrease characteristics.