Abstract: The elastic-plastic contact problem between rail and wheel is analyzed when the micro-roughness on contact surface and the liquid existing on rail surface are considered. The stresses on contact surface are obtained. A series of peak values of stresses exist on contact surface, which made the material on the surface of rail and wheel go into plasticity. There exist severe residual stresses on the surface of rail when the contact load is unloaded. After the wheel running many times on the rail, the plastic deformation on the rail would accumulate and the surface of rail would fatigue. The contact stresses and residual stresses on contact surface are given for the case of no liquid existing on contact surface and the case of liquid existing on contact surface. The stresses at crack tip for different surfacial micro-crack are analyzed for the case of no liquid existing on contact surface and the case of liquid existing on contact surface. The crack is easier to grow and will make the surface of wheel and rail to peel off in the case of liquid existing on contact surface.

Key words: Elasticity-Plasticity, Frictional contact, Liquid, Micro-crack on surface, Dimension factors, Residual stress, Stainless steel, Welding deformation