Research On Vehicle Braking Stability On Turn

With the development of transportation and vehicle industry, the transportation safetyproblem becomes more and more serious. Road curved section is quite complex and manytraffic accidents happened at this section. There is thousands of traffic accidents happened atroad curved section every year. Through reason analysis that lead to traffic accidents thathappened at road curved section, it is known that when vehicle brakes suddenly, greatcentriod force and brake force will lead to vehicle lose its stability and traffic accidentshappened.When vehicle drives on road curved section, the adhesion force between tire andground not only provides the driving force or braking force which points to the longitudinaldirection, but also provides the centripetal force which keeps the vehicle turning. If thebraking force is too big, the situation will cause brake wheel locked, vehicle tail jilt or losesteering capacity. The research om vehicle turning braking performance has the vitalsignificance to guarantee safety and reduce the traffic accident rate.The purpose of this paper is to study the braking influence on vehicle stability whenvehicle drives on road curved section. AMESim is used to establish the15DOF vehicledynamic models. External disturbs are considered at the same time. Yaw velocity and theslip angle are selected as the main factors to judge the stability of vehicles.This paper studied two conditions of vehicle stability. In the first operating mode,braking force is the changing factor while speed and turning radii are fixed. In second cases,the steering angle is changing while speed and braking force are fixed. Research shows that:in the first condition, with the increase of traffic speed, critical force is reduced ceaselessly.In speed120km/h, small braking force can make the vehicle losing stability. In the secondcondition, with the increase of traffic speed, critical angle of steering wheel is reducedceaselessly. The results showed that braking and sharp turns and will make vehicle loses itsstability.