Impact of tooth friction and its bending effect on gear dynamics

This work studies the influences of tooth friction on parametric instabilities and dynamic response of a single-mesh gear pair. A mechanism whereby tooth friction causes gear tooth bending is shown to significantly impact the dynamic response. A dynamic translational–rotational model is developed to consider this mechanism together with the other contributions of tooth friction and mesh stiffness fluctuation. An iterative integration method to analyze parametric instabilities is proposed and compared with an established numerical method. Perturbation analysis is conducted to find approximate solutions that predict and explain the numerical parametric instabilities. The effects of time-varying friction moments about the gear centers and friction-induced tooth bending are critical to parametric instabilities and dynamic response. The impacts of friction coefficient, bending effect, contact ratio, and modal damping on the stability boundaries are revealed. Finally, the friction bending effect on the nonlinear dynamic response is examined and validated by finite element results.