Based on the planetary gear transmission system considering the coupling effects of friction and elastohydrodynamic lubrication, a torsional dynamic model considering friction, oil film, time-varying meshing stiffness, meshing damping, and gear backlash is established. The Runge–Kutta numerical method is used to solve the vibration equation of the system. The bifurcation diagram and largest Lyapunov exponent are used to analyze the dynamic characteristics of the system under different bifurcation parameters such as the excitation frequency, lubricant viscosity, sun–planet backlash, and planet–ring backlash. The numerical results demonstrate that with the increase of excitation frequency, the system exhibits rich nonlinear dynamic characteristics such as short-period motion, long-period motion, and chaotic motion. With the increase of lubricant viscosity, the chaotic motion of the system is suppressed at low excitation frequency and the periodic motion of the system increases at high excitation frequency. With the increase of sun–planet backlash, the chaotic motion of the system increases at low excitation frequency, and the bifurcation characteristics become complicated at high excitation frequency and enters chaotic motion in advance. With the increase of ring–planet backlash, the system delays into chaotic motion at low excitation frequency and bifurcates from single-period motion to multi-period motion in advance at high excitation frequency.
Nonlinear dynamic characteristics of planetary gear transmission system considering squeeze oil film
