| Vehicles on road traffic are becoming large-sized, overloaded with high speed and heavy load. The unevenness of pavement surface has caused heavy vibration of vehicles in high speed and increased dynamic load on road, aggravating the damage to pavement. As the result, waves, ruts and cracks on asphalt pavement and net cracks and breakaway on cement pavement occur, which are closely related to the dynamic load between vehicles and pavements. The conventional design method for pavement based on static load is no longer suited to actual condition. The effect of dynamic load must be considered in design.The dynamics relation in vehicle-road interaction was studied, with the following as the result.Firstly, a model of a quarter of a vehicle with two-degree of freedom was established along side with the finite element model of roadbed-road surface and the input model of flexible pavement.Secondly, the modal truncation method was adopted for the low-ordering of the dynamic finite element model of the roadbed-road surface. The transforming function between pavement deformation and tire force was obtained. The elastic dynamic finite element system of flexible pavement was programmed with MATLAB language, solving the analysis of pavement response under random load.Thirdly, the vehicle-road interaction was studied. The model of transforming function for dynamic coupling system of vehicle and roadbed-road surface was simulated on Simulink system, with the input model of pavement as the excitation. The dynamic tire force was obtained as the response. The response of roadbed-road surface under random load was derived from the dynamic finite element model, applied with the random dynamic tire force above, together with the dynamic calculation by Wilson-θmethod. The analysis showed the decrease of vertical dynamic stress with depth in pavement. The effects of vehicle speed and roadbed rigidity on dynamic deformation of pavement, dynamic tire force and vertical acceleration were analyzed. The relation between dynamic tire force and dynamic deformation of road surface was analyzed as well.Finally, the simulation of control strategy for vehicle active suspension was carried out. The effect of linear quadratic Gauss (LQG) suspension system on dynamic tire force, acceleration of vehicle and dynamic deformation response of road surface was analyzed by applying LQG active control suspension system. Simulation analysis shown that active suspension can lower the dynamic load to the road surface under driving vehicle and reduce the dynamic deformation of the pavement.
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