Nonlinear characteristic analysis of gear rattle based on refined dynamic model

Abstract

In order to explore the vibration response and the nonlinear behavior of gear rattle, a nonlinear dynamic model is developed in this paper considering the nonlinear oil film force, time-varying meshing stiffness, dragging torque and friction and gear backlash with time-varying characteristics. The time-varying meshing stiffness is calculated using the potential energy method. Considering the convolution and extrusion of the lubricant between the teeth, it is modeled as a nonlinear spring-damped element and a nonlinear oil film force is introduced. The drag torque is calculated numerically using fluid dynamics theory, friction principle, momentum conservation principle, and Bernoulli's principle. The model is verified by comparing the bench test results with the simulation results, and the parametric study is performed to investigate the nonlinear system characteristics by means of fast Fourier transform, Poincare map, and bifurcation diagram. The results show that as the excitation frequency increases, the system enters chaotic state under multiple frequency jumps. Excessive torque fluctuation may lead to severe rattling phenomenon of the gear pair and making the system enter a chaotic state; as the lubricant viscosity increases, the system shows periodic, bifurcation and chaotic behavior alternately, and when the viscosity is large enough, the high-frequency shock intensity decays more rapidly due to large drag torque, which is beneficial to reduce the percussion strength and prevent the system into chaos.