Investigation On Dynamics Of Heavy Vehicle-pavement-foundation Coupled System

With rapid development of highway transportation and increase of vehicle loads,the early damage of pavement on expressway caused by vehicle dynamical tire forces is more and more serious.The road damage leads to vehicle vibration increase,which may reduce the vehicle's driving safety and riding comfort.As a result,dynamical tire forces increase greatly.Thus the vehicle and pavement are interacted and coupled.Howerver,the vehicle and pavement are investgated seperately in vehicle dynamics and pavement dynamics.In vehicle dynamics,the road surface roughness is regarded as excitation to vehicle,and the dynamical behavior and the parameter optimization of the vehicle are investigated.In pavement dynamics,the vehicle is regarded as moving loads acting on pavement,and dynamical responses and life span of pavement are investigated.In this dissertation,the vehicle model,pavement model and foundation model are linked to a great vehicle-pavement-foundation coupled system by dynamical tire forces. Based this coupled system,dynamics of vehicle and pavment are researched simulately. The dynamical tire forces are computed by traditional point contact model and the revised flexible roller contact model proposed by this dissertation.The linear vehicle and pavement,and the nonlinear vehicle and pavement are studied.The elstic and viscoelastic pavement material are considered.By methods of integral transformation, mode superposition and direct integral,responses of linear vehicle-pavement system are researched.By methods of Galerkin,averaging,multi-scale,Melnikov function and numerical simultaion,responses of nonlinear vehicle-pavement system are researched also.Dynamical responses of traditional point contact tire model and the revised flexible roller contact tire model,traditional system and coupled system are compared respectively.The effect of parameters of vehicle and pavement on vehicle riding comfort and road damage are analyzed detailedly and measures of parameters' low -dynamic design are concluded.It is found that the second road displacement excitation proposed in this work is able to reflect spacial repeatability of dynamic tire forces;the impulsive reponse obtained by the revised elastic roller contact tire model is more close to test data than the point contact tire model;the coupling action between vehicle and pavement depends on vehicle load,foundation stiffness,and amplitude of road surface roughness;with increase of vehicle load,foundation stiffness,or amplitude of road surface roughness, the coupling action become more obvious;the effect of vehicle running velocity and pavement density on vehicle riding comfort and road damage is fluctuate;Decrease of vehicle load,tire mass,tire stiffness or suspension stiffness,or increase of foundation damping is benefit to both vehicle riding comfort and control of road damage;the effect of nonlinearity of vehicle and pavement on vehicle body vertical acceleration is bigger than that on pavement vertical displacement;the effect of viscoelasticity of pavement material on vehicle body vertical acceleration is smaller than that on pavement vertical displacement and responses of pavement with viscoelastic material are bigger than that of pavement with elastic material.