Study Of The Nonlinear Vibration Characteristics Of The Vehicle Suspension System

The good and bad of performance of vehicle suspension system directly affect the riding comfort and the handling safety, so designing excellent suspension system is very important to improve vehicle quality. At present, vibration characteristic analysis of non-linear suspension is already a significant subject in the field of vehicle suspension research.Firstly, the thesis adopts the non-linear stochastic vibration vehicle model of two degrees of freedom, analyzes the dynamic characteristic property of conical helical spring and builds the mathematical model of road roughness; then using statistic linearization method, translates the non-linear stochastic vibration equation of suspension system to equivalent linear stochastic vibration equation, analyzes dynamic statistic characteristic of two-degree-freedom vehicle suspension system by using the theory of linear stochastic vibration, receives the relative graph between encouragement variance and respond variance, computation results show that it is feasible and dependable to apply statistic linearization method to resolve the problem of non-linear stochastic vibration of vehicle suspension system. Secondly, the stability of vehicle suspension system is researched by utilizing Lyapunov stability theorem, the theoretical analysis and simulation results show that the suspension system is stable in given parameter and time frequency in this paper. Finally, Linear Quadratic Optimal Control regularity is used to control the non-linear suspension and MATLAB/Simulink simulation is applied to simulate the controllable effect of linear-passive suspension system, non-linear-passive suspension system and non-linear-active suspension system respectively.The thesis research results indicate that the suspension non-linear factor can obviously affect the comfort and the steady of vehicle, so it must not be ignored in designing suspension; the dynamic performance of non-linear-active suspension system based on linear controllable theory is better than that of non-linear-passive suspension system, and much better than that of linear-passive suspension system.