Study of time-varying mesh stiffness of spur gears considering lubrication state and surface topography

Considering the influence of actual surface topography on the contact state of gear pairs under elastohydrodynamic lubrication (EHL), a segmented calculation model for the Time-varying mesh stiffness(TVMS) of rough surfaces under lubrication conditions was established based on the Weber energy method, W-M fractal function, and fundamental equations of EHL. The contact potential energy was divided into asperity contact potential energy, mixed contact potential energy, and oil film contact potential energy according to the lubrication state. The variation patterns of gear contact stiffness(CS) and TVMS under full-film lubrication, mixed lubrication, and boundary lubrication were investigated. The effects of different surface roughness, torque, and rotational speed on tooth surface CS and gear TVMS were analyzed. The reliability of the proposed method was verified through model verification and comparative analysis. The results show that surface roughness, torque, and rotational speed have a segmented function trend on the TVMS and exhibit different variation patterns under different lubrication conditions. This study provides a theoretical basis for the design and optimization of gear transmission systems.