Effect of laser textured patterns on friction coefficient of wheel/rail materials under mixed lubrication

To investigate the influences of regular patterns on friction coefficients of wheel-rail contact under mixed lubrication, longitudinal, transverse and rhombus patterns are designed. The film thickness, pressure and contact area ratio are calculated by using deterministic model instead of average flow model. Based on the loadsharing concept, the hydrodynamic film and asperities both contribute to carrying the total load. Therefore the friction force is composed of hydrodynamic friction force and asperity friction force. According to the designed patterns, the surfaces of wheel discs are textured by YAG laser. The friction coefficients are tested on a RSW-2 type wear testing machine and the results are compared with that of the grinded without laser textured. It is shown theoretically and experimentally that the friction coefficient of rhombus pattern is higher than that of longitudinal and transverse patterns. And the friction coefficient of longitudinal pattern is slightly higher than that of transverse pattern. Therefore, laser texturing of the textured surface with rhombus distribution can increase the friction coefficient obviously between wheel and rail under oil-contamination condition.