Study On Off-road Dynamic Tire Model Based On Three Dimensional Rigid Ring

Accurate tire model is the necessary premise that realize the high precision simulation of vehicle dynamics. After a long time of development, many scholars have suggested a lot of high-precision on road tire models, and there are many business tire model available. Under the condition of off road, because of the deformation of terrain, tire sinks to the soil, together with the complex characteristics of soil, the generation of tire force, interaction mode of tireterrain and the modeling ideas varies greatly with on-road condition. Off-road tire model has important significance to the validation and development of dynamics performance and electronic control system of off-road vehicles, military vehicles and special vehicles. Based on the idea of three dimensional rigid ring, through comparison and analysis the tire-terrain interaction model, this paper establishes the off-road dynamic tire model. Through simulation and verification, the model simulation results are consistent with the test and simulation data from the foreign literature, which verify the correctness of this model.Firstly, this paper thoroughly analyses the tire-terrain interaction semi-empirical model. Semi-empirical model meets the requirements of the computational accuracy and real-time simulation simultaneously. This paper researches the semi-empirical tire-terrain interaction models extensively, which including the pressure-sinkage model, the shear stress model, the slip-sinkage model and the bulldozing force model, and analyses the modeling methods and application conditions. It provides the basis for the selection of interaction model.Secondly, this paper establishes the three dimensional rigid ring tire dynamics model. According to the deformation of the tire and the character of deformation of terrain on the offroad condition, this model assumes that the tread of tire does not deform, modeling the wheel into three parts as three dimensional wheel rim, three dimensional rigid ring and the springdamper in six directions. In the space the rim and rigid ring both has six degrees of freedom. The rim and the rigid ring connected with spring-dampers, which used to describe the inflatable elastic of carcass. According to the characteristics of three dimensional rigid ring, the calculation method of tire and terrain contact range and the dynamic shear velocity is determined. Using the tire-terrain interaction semi-empirical methods, the normal stress model, longitudinal shear stress model, lateral shear stress model and lateral bulldozing force model acting on the rigid ring are established, which used to calculating the tire force. Using the multibody dynamics method, the rim and rigid ring dynamics model are established respectively, and the dynamic state of rim and rigid ring is described completely.Finally, simulation analysis and experimental verification of the mode are carried out. Experiment data of rigid wheel received from published literature is used to verify the tireterrain interaction force model. The results show that the model calculation results are in agreement with the experimental data. Through the steady-state simulation of tire model, respectively, in vertical loading condition and the combined slip condition, this paper gets the stress distribution features acting on rigid surface and the tire mechanical properties of longitudinal and lateral. According to the mechanical properties, this paper analysis the traction, braking and steering performance of tire on off-road.