Numerical Simulation and Experimental Analysis of Grease Friction Properties on Textured Surface

This research article is a numerical simulation study and experimental verification of the frictional behaviors of grease lubricated sliding contact under mixed lubrication conditions. The influences of surface texture parameters on the frictional properties were investigated. A numerical simulation model was specifically developed in MatLab which employs the average flow Reynolds equation established on the basis of finite-element analysis to compute the friction coefficient, pressure distribution, and film thickness. The results showed that friction coefficient is largely dependent on texture parameters with higher and lower dimple depths resulting in higher friction coefficient at a fixed dimple density. The sample with texture density of Td=15% and texture depth of H3=7m exhibited the best friction properties experimentally, because it can store more grease and trap wear debris. Through the comparison of the simulated results of the current model with the ring-on-disc experimental results, the validity of the mixed lubrication model was confirmed. However, the lowest friction coefficient occurs at dimple depth of 5m and texture density of 10% which is slightly at variance with the experimental results. The simulated results exhibit the reduction of friction for surface texturing and the main mechanism for such an effect may be attributed to the hydrodynamic pressure effect of the surface texturing, which increases the mating gap and reduces probability of asperity contact.