Research On The Influence Of Longitudinal Impulse On The Running Comfort Of Urban Rail Transit Vehicles

With the development of China’s economy,the increase of the number of population,the expansion of the urban scale,resulting in the urban urban traffic pressure is more and more,the development of urban rail transit demand is increasing day by day.Passengers in the pursuit of convenience,fast and safe traffic at the same time,more and more attention to ride comfort.There are many factors affecting comfort,among which the vibration acceleration of the car body is the most important one in most evaluation criteria.Vibration acceleration mainly includes transverse acceleration,vertical acceleration and longitudinal acceleration.This paper mainly studies the influence of longitudinal impulse caused by longitudinal acceleration on the comfort of urban rail transit vehicles.This paper describes the process of longitudinal impulse and the basic factors that lead to longitudinal impulse,and analyzes the train braking force,locomotive traction force and train running resistance related to longitudinal dynamics.Four commonly used comfort evaluation methods,Sperling stability index,ISO2631 evaluation method,GB5599-85 standard and UIC513 evaluation method,were introduced.Combined with the research direction of this paper and the advantages and disadvantages of each evaluation standard,considering the need for longitudinal acceleration analysis,UIC513 evaluation method was finally selected as the comfort evaluation method in this paper.Based on the dynamics simulation software of Simpack,this paper USES the multi-rigid body system dynamics theory to establish the dynamics model of a certain subway Type B car for a single cycle and a four-motion two-towed train.Three different lines,including straight lines,ramps and curves,were established.With the American five-stage track spectrum as the external excitation,SODASRT2 integral method was adopted to solve the transverse acceleration,vertical acceleration and longitudinal acceleration of the train when passing through different lines.Matlab software is used to compile the program of UIC513 evaluation method to realize the fast calculation and result display of the comfort index of the train under different working conditions.Trains run at different speeds in straight lines through idling lines;Idle trains run on curves and ramps;Idle trains and variable speed trains run in a straight line;Idle trains and variable speed trains run on ramps;By comparing the transverse,vertical and longitudinal accelerations and coupler forces of the train running on the curve,the influence of longitudinal impulse on the comfort of the train under various operating conditions is analyzed.The results show that the higher the speed is,the greater the longitudinal impulse is and the worse the comfort is.The longitudinal impulse of idler trains is greater than that of straight line trains when running on curves and ramps,and the train comfort is worse.Compared with idle trains,variable speed trains have greater longitudinal impulse and lower comfort when running in straight line,curve and ramp.In this simulation test,it can be seen that the influence of longitudinal impulse on comfort cannot be ignored.On this basis,urban rail vehicles can be tested in actual operation lines to make the data more accurate.It has certain reference value to improve the running stability and comfort of urban rail vehicles.