Research on bifurcation and chaos characteristics of planet gear transmission system with mixed elastohydrodynamic lubrication (EHL) friction

Abstract In order to study the influence of friction on the nonlinear dynamic characteristics of a planetary gear system, the dynamic model of a planet gear transmission system considering mixed elastohydrodynamic lubrication (EHL) friction, time-varying meshing stiffness, backlash and comprehensive meshing error is established. The Runge–Kutta method is used to solve the dynamic differential equations, and the bifurcation and chaos characteristics of the system are analysed through the bifurcation diagram, largest lyapunov exponent (LLE), Poincaré map, phase diagram, time history curve diagram and fast fourier transform (FFT)spectrum. The results of numerical simulation show that the planetary gear system with mixed EHL friction exhibits rich bifurcation characteristics, and the system experiences short-periodic motion, long-periodic motion, quasi-periodic motion and chaotic motion. The effect of tooth surface friction on the bifurcation characteristics of the planetary gear system is more obvious at high frequency than that at low frequency. Tooth surface friction causes the system to enter chaotic motion in advance.