Research On Vehicle Crosswind Stability With AMC Two-way Coupling Method

With the rapid extension of the high way,the environment where the vehicle running becomes more and more complex.When the vehicle is running in the complicated environment,it will be affected by the road or crosswind.Therefore,it is necessary to study the automobile in this complex environment.However,at present,the research on the vehicle crosswind stability mainly adopts one-way coupling approach,such as researches based on aerodynamics or vehicle dynamics.But,the researches of aerodynamics cannot evaluate the influence of the aerodynamic force on the vehicle motion.And the dynamics studies neglects the influence of vehicle attitude on aerodynamic forces.Therefore,neither of them can fully analyze the crosswind stability of the vehicle.Although a few scholars have used coupled methods to study crosswind stability,the coupled vehicle dynamic models mostly use mathematical models which cannot reflect the detailed structure and are quite different from the actual ones.Therefore,to solve this problem,the multi-body system dynamics model is used to consider the detailed structure of the vehicle,and the aerodynamic model is used to consider the transient changes of the flow field around the vehicle,and the aerodynamics and multi-body dynamics coupling is implemented.The study of Aerodynamics and Multi-body Dynamics Coupling(AMC)approach is established to analyze the crosswind stability under the combined influence of crosswind,road,and driver.It is meaningful for practical theoretical guidance and engineering reference value.The main research content of this article is as follows.1.A vehicle aerodynamics simulation model is established with Fluent,and the aerodynamic model's tail flow field and its aerodynamic force as the vehicle attitude changing is verified by wind tunnel tests.A multi-body dynamics(MBD)model,a driver model and a road model are established with Adams/car.The robustness of the multi-body dynamics model is analyzed by moving the center of the pressure forward and backward,upward and downward to consider the ability to capture the supposed crosswind stability trends.2.A AMC two-way coupling method based on Fluent and Adams/car is developed,and the ISO crosswind stability road test standard was described.Based on this standard,a crosswind numerical simulation method under standard test conditions is established.The AMC method is used to study the difference of one-way coupling and the two-way coupling.It is shown that the AMC two-way coupling method is essential to study the vehicle stability in crosswind.3.The AMC two-way coupling method is used to study the influence of driver intervention and driver preview time on the stability of the vehicle crosswind under standard test condition,and the vehicle stability in steady natural crosswind is also analyzed.The crosswind stability of vehicle is compared when the steering wheel is locked or not in two different crosswind environments.4.The AMC two-way coupling method is used to introduce the impact of road on the crosswind stability of vehicle,including the impact of road friction coefficient and road roughness.Then the vehicle crosswind stability on low friction road is analyzed in two kinds of crosswind and the steering wheel locked or not.The influence of the driver's intervention and crosswind type on the vehicle crosswind stability on road with high unevenness was also studied.