Dynamics Modeling And Analysis Of Vehicle-pavement Nonlinear Coupling System

Based on the basic theory of vehicle,tire and pavement dynamics,the vehicle-pavement nonlinear coupling system is simplified and decomposed into vehicle,pavement,tire model,and vehicle-pavement coupling system model in this dissertation.The hysteretic nonlinear energy sink(HNES)is used as the driver of the semi-active suspension system of the 1/2 vehicle model to research the vehicle vibration responses under both of the impulseive pavement roughness excitation and the stationary random process.The radial distribution nonlinear multi-nodal spring-damper tire model(RNMST)is proposed in this dissertation.The RNMST is applied together with the nonlinear multi-nodal spring-damper tire model(NMST)and the nonlinear single nodal spring-damper tire model(NSST)to the vehicle-bridge coupling system.Based on both of the continuous iteration theory and mode superposition method,the vibration responses of the coupling system under the excitation of stationary random pavement surface and the bandwidth-limitation white noise signal are analyzed.The direct time integration method is used to solved the motion differential equations of 1/2 passive and semi-active suspension vehicle model at different velocities and external excitation,and the analytical solutions are obtained.The measurement method of multi-sensor pavement spectrum based on inertial coordinate datum is improved,and a fast pavement spectrum acquisition system based on multi-sensor and actuator is developed.The main research contents and results of this dissertation are as follows:(1)With the ISO international standard pavement displacement power spectrum,based on the statistical characteristics of stationary random process,bandwidth-limited white noise and low-pass filtering method,random pavement roughness excitation samples are generated combining with power function and trigonometric series theory,and the power spectral density(PSD)function of random pavement roughness excitation samples is calculated and analyzed.The vibration responses of the vehicle-pavement coupling system under two types of pavement roughness excitation and different vehicle velocities are compared and analyzed respectively.(2)The direct time integration method(DTIM)is used to solved the motion differential equations of the 1/2 semi-active suspension vehicle system under both impulsive pavement roughness and stationary random pavement roughness excitations at different vehicle velocities to study t he vibration characteristics of vehicle system.The driver model is introduced to evaluate the ride comfort and safety of the vehicle.It’s found that when the HNES model is used as the driver of the vehicle semi-active suspension system,the vehicle velocity changed from 1.1256m/s to 20m/s in the process of impulsive pavement excitation and stationary random pavement roughness excitation the driver,vehicle chassis vertical displacement,vehicle chassis pitch angle displacement,tire vertical displacements,and velocity responses are better and more stable than the magnetorheological damper model as a semi-active suspension driver vehicle vibration characteristics.(3)Based on the radial distribution nonlinear multi-node spring-damper tire model(RNMST),the vibration response of a quarter vehicle system under two kinds of pavement roughness excitation is studied.The motion differential equation of the vehicle-bridge coupling system using vehicle as the moving concentrated load is established.Adopting Newmark-β and Newton combination method and modal superposition method,the vibration characteristics of the nonlinear coupling system based on different external excitation is obtained.Combined with the vehicle-bridge acceleration spectrum,the comprehensive mechanical properties of the radial distribution nonlinear multi-node spring-damper tire model and the nonlinear multi-spring-damper tire model,compared with the nonlinear multi-spring-damper tire model(NMST)and the nonlinear single point contact spring-damper tire model(NSST),the RNMST model has better stability performance in vibration response form the calculation results.(4)By researching the vehicle-pavement coupling vibration system and the vehicle chassis control system,the vehicle ride,attitude,and controllable performance are evaluated.It is found that in the process of vehicle driving on the bridge,the tire and the pavement surface are temporarily separated due to both pavement roughness excitation and dynam ic vibration of the bridge.Based on the study of the horizontal component of the relative contact force of the tire and bridge coupling process,it is found that the dynamic response characteristics of the vehicle model are not only related to the external excitation,but also to the influence of the horizontal component of the tire dynamic contact force,which should be considered and taken seriously.(5)The pavement spectrum measurement method of the sensor based on the inertial coordinate datum has errors in collecting pavement parameters,because the measurement platform-vehcile has its own pitch and roll motion.Based on the improved straight beam datum laser-displacement sensor method to obtain pavement spectrum structure,a fast pavement spectrum me asurement method based on inertial coordinate datum combining sensor with actuator is proposed as well,and then the corresponding computer software is developed.The roughness data and power spectral density samples of different types and grades of paveme nt surface are obtained through experiments,and compared with the international standard pavement spectrum,the correctness and effective performance of the improved method and the feasibility of virtual pavement surface roughness excitation method adopte d in this dissertation are obtained.