Gear tribological and contact fatigue prediction with rough topography and groove texture under elastohydrodynamic lubrication

The introduction of micro-texture on gear tooth surface can potentially enhance the contact fatigue life and operational reliability of the gear pair, and is attracting increasing attention in an effort to provide improved tribological properties and contact performances. In this work, a new tribological model of micro-textured gear tooth in elastohydrodynamic lubrication (EHL) contact considering the coupled effect of rough surface topography is developed. The combined effect of micro-texture, surface roughness topography, elastic deformation of the tooth surface and lubrication on the contact characteristics of the meshing interface are included to obtain a revised oil film thickness equation. The rough surface contact of gear pair is characterized by the real rough morphology of gear tooth. The coefficient of friction at the transient meshing point of the micro-textured tooth surface is derived with the effect of flash temperature included. The sub-surface stress–strain distributions of the micro-textured gear are determined and the contact fatigue life is evaluated based on the Brown-Miller-Morrow multiaxial fatigue life criterion. Effects of surface roughness and micro-texture parameters on the lubrication behavior, friction coefficient and fatigue life are investigated and discussed. Experimental validation is performed and good agreement is observed between the model predictions and experimental results.