| Railway,the main artery of transport,plays an important role in the growth of the national economy.At present,all countries are striving to develop high-speed railway and have made some achievements.C hina is also actively developing rapid rail transport.The opening of high-speed passenger line provides favorable conditions for the rapid delivery of freight.At the same time,it also puts forward higher requirements on the speed of freight trains.Thus,the development of fast trucks becomes quite important.Since 2000,C hina has developed a series of fast trucks and has made some achievements,but it still needs some time to successfully realize commercial operation of the rapid trucks because current technology is not mature enough and there is no related standard.In addition,some key technologies that deal with high-speed operation of the train have not been resolved,especially the stationarity and stability of the movement are urgent to be resolved.Based on the above background,this paper carries out the research on the dynamic characteristics of fast truck's lateral movement and the optimization of the system parameters.Combined with the technical characteristics and running speed of the fast truck in China,this paper applies the classical multi-rigid body dynamics theory and established the nonlinear mathematical model of the fast truck system with 19 degrees of freedom.This model takes some strong nonlinear factors into consideration,such as nonlinear wheel-track interaction force,central plates,and dry friction between side bearings and truck body.In addition,the dynamic behavior and the bifurcation behavior of the vehicle system in the linear or steady-state orbit are respectively studied by means of numerical integration method,which contributes to the overall understanding of the movement characteristics of the vehicle system.At the same time,the influence of the suspension parameters and structural parameters of the vehicle on the dynamic performance of the vehicle system is studied in order to optimize the dynamic performance of the vehicle and provide a theoretical reference for the vehicle optimization design.The results show that the greater the longitudinal and lateral stiffness of the first suspension is,the smaller the critical velocity of the vehicle is;the greater the lateral stiffness of the secondary suspension is,the smaller the critical velocity of the vehicle is.When the longitudinal stiffness of the secondary s uspension increases,the critical velocity of the vehicle firstly goes up and then declines.The coefficient of friction between the wheel and the rail and the equivalent taper of the wheel towards the tread have a significant effect on the critical velocity.When the friction coefficient between the wheel and the rail increases,and the critical velocity of the vehicle goes up obviously.And when the equivalent taper of the wheel towards the tread increases,the critical speed of the vehicle declines obvio usly.When the running speed of the vehicle is more than the critical speed,the asymmetric motion process appears in the symmetrical system.Also,the symmetrical motion process appears in the asymmetric system.With the change of these parameters,the system also shows different dynamic characteristics.In this paper,the optimal value range of each parameter is obtained by analyzing the influence of these parameters on the dynamic performance of the vehicle system,which provides a certain theoretical re ference for improving the dynamic performance of the vehicle and designing a type of fast truck with better speed and dynamic performance. |
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