Study On Curve Performance Of Low-floor Trams Capable Of Perfect Steering

With the rapid development of urbanization in our country,the problems of dense population,environmental pollution and traffic congestion have become increasingly prominent.Traditional road transportation has been unable to meet the daily trip demand of citizens,which promotes the application of urban rail transit system.As an important part of the current urban rail transit system,low-floor tram is favored by more and more cities because of its advantages such as convenience,safety,and energy saving.Limited by the existing urban traffic lines,lowfloor trams need to pass many small radius curves,so its curve performance is worthy of further study.Firstly,this thesis gave a brief overview of the development of trams.The research present situation of guidance performance at home and abroad was summarized.At the same time,several guidance technologies mainly used in low-floor trams were introduced.This thesis expounded the exploration of the relationship between steering and dynamic stability by Wickens,and focused on the perfect steering theory.For the low-floor tram,the operation speed was not high,but the curve passing performance needed to be excellent.It was necessary to explore the application of perfect guidance technology in low-floor trams.Secondly,In order to derive the structural form and geometric relationship of the vehicle that met the perfect steering and dynamic stability,a transverse mathematical model of three module low-floor tram with 30 degrees of freedom was calculated,and a preliminary discussion of the configuration scheme was conducted.The dynamic simulation model of low floor tram was established by using SIMPACK software,and the assumptions,non-linear relationships,articulation devices,and guide mechanisms in the model were explained in detail.Finally,the result indicated that too stiff or too soft stiffness of the steering linkages would led to low speed instability of perfect steering vehicles.And low conicity instability occurred when the equivalent conicity was less than 0.05.By optimizing the parameters of longitudinal shock absorbers between the car-bodies,the dynamic stability of the vehicle met the requirements.The ride performance and curving ability of the tram were researched,and the results showed that their ride comfort index was less than 2.5 at a speed of 70 km/h,which reached the superior standard.Compared with the traditional structure vehicle,the curve performance of the perfect steering vehicle was greatly improved,and the wheel wear was significantly reduced.