Study On The Rollover Stability Of Articulated Steer Engineering Vehicle

Articulated steer engineering vehicle travels on complex road, its working condition isbad, and when steering, the center of gravity will offset laterally which will lead a higherprobability of rollover accident. By the financial support of National Natural ScienceFoundation of China (NO.51175216) and Ministry of Education Fund for the Doctoral(NO.20100061110014). This paper aims at the rollover stability of articulated steerengineering vehicle systematically, suitable indicators for the dynamic rollover stability ofthe articulated engineering vehicle were proposed and a7DOFs nonlinear dynamics modelwas established. Then the dynamics model was validated by the physical prototype test andvirtual prototype simulation. Finally, measures for improving the rollover stability of thearticulated engineering vehicle were presented.On the basis of domestic and overseas researches on the index of the rollover stabilityof the articulated steer engineering vehicle, and considering the characters of articulatedsteer engineering vehicle and the reasons of lateral instability, the effects of steering angle,lateral acceleration and the roll angle were analyzed, and then the insufficient of eachindicator was discussed. Based on the above analysis, the indicators which are suitable forthe articulated steer engineering vehicle were proposed.Basing on the Lagrange method and virtual work principle, and comprehensivelyconsidering three rotary motions, a7DOFs nonlinear dynamics wheel loader model wasestablished. The inputs of this model are structure parameters, articulated steer angle, angleof gradient, velocity and etc., and basing on the dynamics and kinematics characteristics ofthe articulated vehicle, the outputs are roll angle, roll angular velocity, lateral acceleration,lateral-load transfer ratio etc. Then the established model was analyzed by using thebackward difference method. In order to verify the reliability of the established dynamicsmodel, a scaled articulated loader was built and tested in different working conditions, suchas turning on the level ground, turning on the slope, moving through obstacles and etc. Acorresponding virtual prototype model was built, and relevant simulations about the modelswere carried out. By comparing the lateral dynamic model simulations, the test results, andthe virtual prototype simulation results, it shows that the degree of agreement is relativelyhigh, so the correctness of the established dynamics model is validated.By using the established dynamics model, detailed analysis of the influencing parameters of a wheel loader’s dynamic rollover stability was carried out, and theparameters include corner velocity, turning radius, articulated steer angular velocity, angleof gradient, the distance between the front axle and the hinge axle, the distance between therear axle and the hinge axle, wheel tread, oscillating axle and etc. Through analysis, itshows that as for the vehicle on the level ground, the influence of the oscillating axle is notlarge, but if on the slope, its influence is very large. The analysis results have somereference values in improving the design of the rollover stability for articulated engineeringvehicle.According to the conclusions from the analysis, an improving plan was proposedbasing on the oscillating axle. In this plan, by adding sensing, controlling and hydrauliccomponents, the passive oscillating axle was changed to be an active one; when the vehicleis moving on the level ground, there is almost no difference between the passive and theactive oscillating axle on the obstacle performance; but when travelling on the slope, theactive oscillating axle could strengthen the rollover stability by limiting the swinging of therear axle. Simulations of the improved vehicle were carried out. The analyzing results showthat, this plan could improve the rollover stability of the articulated steer engineeringvehicle.A rollover dynamics model which more comprehensively considering the engineeringvehicle features was established; the indicators that are suitable for the rollover stability ofthe articulated steer engineering vehicle were proposed in this paper; and the passiveoscillating axle was replaced by the active oscillating axle which could improve theperformance of vehicle’s rollover stability. This research provides a basis for the design ofthe engineering vehicle safety and the development of active safety technology forarticulated steer engineering vehicle, and it has an important significance in improving theoperational safety and protecting the life of the driver of the articulated steer engineeringvehicle.