Nonlinear dynamic characterization of sliding bearing-planetary gear system

In order to investigate the motion law of a planetary gear system under the influence of oil film force and analyze the impact of nonlinear oil film force on the system's dynamic characteristics, this study proposes a nonlinear dynamic model for a 39-degree-of-freedom plain bearing-secondary helical gear planetary system. The model takes into account various nonlinear factors such as nonlinear oil film force, time-varying meshing stiffness, and tooth-side clearance. The differential equations are solved using the fourth-order variable step-size Runge-Kutta method. By plotting bifurcation diagrams, phase trajectory diagrams, Poincar & eacute; mapping diagrams, and dynamic load response diagrams, the study examines the bifurcation, shock, and dynamic load characteristics of the system. Furthermore, it explores the effects of nonlinear oil film force and bearing clearance on the system dynamics. The results indicate that the system exhibits more complex dynamics due to the interaction of multiple nonlinear factors. As the excitation frequency changes, the system shows three distinct chaotic regions at low, middle, and high frequencies. The remaining regions are mainly characterized by 1 T-periodic and 2 T-periodic motions. Additionally, the gear meshing process undergoes three shock states: no shock, tooth surface shock, and two-sided shock. The presence of nonlinear oil film force effectively suppresses chaos generation in the system and reduces tooth back shock. Excessive or insufficient bearing clearance leads to high dynamic loads, deterioration of mesh condition, and an increased range of chaos.