Tribo-dynamic model and fatigue life analysis of spiral bevel gears

In gear transmissions, there is a tight relationship between the gear nonlinear dynamics and the tribology. Due to the complicated kinematic and meshing properties, there are lack of investigations of tribo-dynamics in spiral bevel gears. For this reason, a tribo-dynamic model of spiral bevel gear is proposed at present study through an iterative numerical scheme to bridge an eight degree-of freedom nonlinear dynamic model with a recently developed mixed lubrication model. The tribo-dynamic model can handle the complex gear contact geometry, entraining flow angle and real machined surface roughness. Based on the surface normal pressure and tangential shear obtained from tribo-dynamic model, the fatigue life is simulated using a rolling-contact fatigue (RCF) life model. The results show that the tribology has a significant influence on gear nonlinear dynamic behavior, especially in the vicinity resonance. In addition, in comparison of the simulation results between the tribo-dynamic and quasi-static conditions, evident deviations are observed, pointing to the important role of the gear dynamics in the lubrication performance and fatigue life in spiral bevel gears.