A time-varying meshing stiffness model for gears with mixed elastohydrodynamic lubrication based on load-sharing

In mixed elastohydrodynamic lubrication (EHL), the load distribution between the gear meshing surfaces is shared by the oil film and the asperities of the gear's rough surface. Based on the load-sharing concept, this paper proposes a time-varying meshing stiffness (TVMS) model for gears with mixed EHL. The initial step involves the utilization of the Greenwood-Williamson model to calculate the contact stiffness of surface asperities, while the lubricating film is assessed using a curve-fitting formula to investigate the influence of gear surface morphology on TVMS. Subsequently, the incorporation of gear fillet foundation deformation and friction enables accurate TVMS determination. The proposed method is employed to examine the meshing stiffness of the gear pair under both dry lubrication and EHL conditions. Comparative analysis reveals favorable agreement between the proposed model and experimental results obtained under dry lubrication, thereby highlighting the superior performance of the proposed approach. Moreover, the time-varying friction coefficient under EHL is computed, and the impacts of gear surface morphology parameters, temperature, speed, and load on lubrication conditions and TVMS are investigated. The findings presented in this paper contribute significantly to advancements in gear design and performance.