Wheel-rail contact in railway engineering is an important topic. Due to different materials and surface roughness of wheel and rail, the contact characteristics can alter significantly. This article aims to investigate the effects of surface roughness and asperities on the contact parameters such as contact area, contact force, and contact stiffness. The lateral contacts between asperities are assumed to be the general contact condition. Azimuthal and contact angles distributions are assumed to be spherical harmonic distribution. This assumption is compatible with the asperity distribution on the wheel and the rail surfaces. Besides, a new combined model is developed to cover the stick-slip and the plasticity effects in contacting asperities. The results of the presented model offer very good estimations for the asperities contact characteristics, especially at the small-contact area and separation where high-contact pressure and plastic deformation usually exist.

The roughness effects on the wheel-rail contact problem is an essential topic. In this paper, a new analytical-numerical model has considered assessing the specifications of a rough surface contact problem. The new model includes asperities and strain hardening effects together. Consideration of these assumptions is more realistic in comparison to similar simplified works. In this work, the effects of material properties variation on a contact problem realize. Besides, considering the strain hardening effects, the contact results for wheel-rail material are obtained. The contact characteristics variations versus separation, such as contact force, contact stiffness, and contact area, are shown in semilogarithmic diagrams considering different surface roughnesses and hardening parameters. The new model results show the significant influence of the assumed hypothesis on the contact characteristics.