The Research On Dynamics Of The 7-module-low-floor Rail Vehicle Under Traction

With the acceleration of the urbanization,the planning of rail transit begins to extend to the urban.And the low-floor tram has been accepted by more and more cities due to its features of low construction cost,reasonable transport capacity,humanized design,energy conservation and environmental protection.At present,there are mature models of three modules and five modules,but with the increase of passenger flow in the future,the longer train will be used.Therefore,it is necessary to focus on the research of seven-module low floor tram.In addition,in the previous studies on low-floor tramcar dynamics,the analysis is carried out based on the condition that the train is at a constant speed,and the dynamic performance of the train under the traction is not involved.Therefore,in this paper the dynamic performance of the seven-module low-floor tramcar under the traction condition is conducted.This paper firstly introduces the development of low-floor tram and summarizes the research status.The structural scheme of seven-module low-floor tram is introduced in detail.The multi-dof dynamic model of seven-module low-floor tram is established by using SIMPACK software.After verifying the rationality & correctness of the dynamic simulation model,the dynamic performance of the train under idling condition is analyzed.The results show that,under idling condition,the vertical stability performance of the cab module is poorer,and the lateral stability performance of F2 module is poorer.When the train passes the curve under idling running condition,the safety indexes of the front axle are higher than the rear.Furthermore,the longitudinal force with fluctuation property is also included in this research,and the dynamic performance of the seven-module low-floor tramcar under the traction condition is analyzed by setting up two conditions: ramp and curve.The results show that when the train passes the ramp,the longitudinal force fluctuation amplitude is the largest,followed by the vertical force,and the transverse force fluctuation is the smallest.When passing through the horizontal curve of the train,the rotation angle between the vehicle bodies is greater than the deflection angle and the nod angle between the vehicle bodies,and the longitudinal force and vertical force of the articulated device are more affected by the traction torque,while the transverse force of the articulated device is more affected by the line conditions.Besides,by setting different traction conditions,the influence of the traction process on the dynamic performance of the vehicle is further studied.The results show that different traction conditions have great influence on the safety index of the bogie module,and the influence on the lateral force of wheel and rail,the lateral force of wheel and axle,the derailment coefficient and the load reduction rate of wheel is obvious.The influence of traction process on each safety index can be divided into two types: one is gradual type,the other is the mutant.In the end,the dynamic performances under the idle condition and the traction condition is compared,the following conclusions are obtained: the introduction of traction will increase the longitudinal force of the articulation device,and the change in acceleration during traction will increase the fluctuation of the longitudinal force of the articulated device;the curve passing performance under the traction condition is worse than that under the idle condition,and the dynamic performance of the acceleration in the circular section of the curve is the worst.Therefore,it is recommended to consider the traction mode in the dynamic calculation.In general,the security and stability indexes,which is calculated under idle running and traction condition,can meet the corresponding standards,indicating that this tram’s dynamic performance can meet the operating requirements.