Study On Vibration Characteristics Of Asymmetric Arrangement Rotor-bearing System And Optimal Design

Rotor-bearing system is one of the most basic parts of rotating machinery,which is widely used in vehicles,aerospace and other fields.When the system is in operation,it is often subject to very complex excitation,which makes the system produce nonlinear vibration and challenges the stability and safety of the system.A large number of scholars have studied the symmetrical arrangement rotor-bearing system,but there are few researches on the asymmetrical arrangement rotor-bearing system.Therefore,in-depth study of the vibration characteristics of asymmetric arrangement rotor bearing system can provide a basis and support for the design,vibration suppression and fault diagnosis of asymmetric arrangement rotor-bearing system.In this paper,the main shaft bearing system of tracked vehicle is taken as the research object.Aiming at the problems of multi excitation and asymmetric arrangement of the system,the inherent characteristics of the system and the influence of system parameters on the vibration characteristics of the system are studied.On this basis,the vibration suppression method of the system is studied.The main work of this paper is as follows:(1)The bearing dynamic model considering oil lubrication and misalignment and spline dynamic model considering manufacturing and assembly factors are established respectively.On this basis,based on the finite element theory,the dynamic model of rotorbearing system with asymmetric arrangement is established.(2)Based on the established dynamic model,the effects of gyroscopic moment,bearing stiffness and shaft stiffness on the natural characteristics of the system are studied;the variable step fourth-order Runge Kutta method is used to solve the system equations,and the effects of turntable,bearing,spline and engine excitation on the vibration characteristics of the system are studied through time-frequency domain,phase diagram,Poincare section diagram and bifurcation diagram.(3)The sensitivity of system response to system parameters is studied by Sobol’s method.Based on the sensitivity results,NSGA-II genetic algorithm is used to optimize the system structure.The first-order response of the system under step input is solved by analytical method.The optimization results are verified and the reason of the first-order torsional vibration of the system under step input is explained.