Impact of roughness

The initial surface roughness of the interface can have a significant influence on tribological contact, especially on the friction behavior. The transition between partial and full sliding regimes can be influenced by the surface morphology and, therefore, the results in the damage mode of fretting cracking in partial slip and fretting wear in full slip. The influence of surface roughness on partial slip condition is quite limited, however, it can change wear rate and wear dynamic in full slip regime. Also, energy required to activate wear mode is lower for a rough surface than for a smooth surface. The dynamics and evolution of the surface roughness in the fretting contact depend on the overall contact loading history experienced by the interface, and it can evolve very rapidly, especially in the first few thousand cycles. In lubricated contact, the surface roughness will influence tribo and physico-chemistry and conditions leading to tribofilm formation. To summarize, in the case of very severe fretting contact conditions, a smoother surface is not always the best solution, and roughness or surface texture can provide better control of the contact and the interface.