Effect of gear mesh stiffness and lubricant nonlinearities on the dynamic response of gear transmission systems

Gear dynamic response is the underlying cause of gearbox noise, vibration, and harshness (NVH) in automotive powertrains. Gear whine, a dominant form of gearbox NVH in electric vehicles, is caused by static and dynamic errors induced mainly by the variation in gear mesh stiffness. Therefore, an accurate evaluation of time-varying mesh stiffness (TVMS) is important. A dynamic model of a simple spur gear system is developed using an improved analytical TVMS method combined with a nonlinear Hertzian contact model. The nonlinear stiffness and damping of lubricant under elastohydrodynamic regime of lubrication (EHL) is adapted to investigate NVH performance of the system. Results from literature are used to verify the model. The effect of nonlinearities on the system stability and response are identified.