Research On Longitudinal Dynamics Of High-Speed Freight Train

Entering into the 21th century,our country economy develop fast.The amount of high added value products have increased rapidly,and these put forward higher requirement for the railway high speed transportation.In order to meet the increasing need of the economic growth and improve competition ability,it's inperative to operate the high-speed freight trains as soon as possible.The promulgation of《the railway primary technology policy》in 2004 has considered the high-speed freight train as one of the major objectives in the development of railway freight car.The running speed of high-speed freight train can be up to 160 km/h.With the increase of speed,the longitudinal force get significantly bigger,and this can cause the fracture of coupler,damage to the carbody and goods,if serious this could endanger security of the train operation.Therefore it's necessary to have the study of longitudinal dynamics for high-speed freight train.Currently,our country has not officially operated the high-speed freight train.According to the actual conditions of vehicle equipments in our country,first of all,the thesis select locomotive and car for the express freight train,meanwhile,propose possible alternatives of brake equipment and draft gears.Then,aiming at the study of high-speed freight train which was established in step one,make the longitudinal dynamics calculations.At last,based on comparative analysis result,give a comprehensive evaluation of our existing brake equipment and draft gears.Specifically,the following four aspects were investigated:1.According to the foreign experience and the actual conditions,the locomotive selection of express train is SS9,which is the main locomotive for our quasi-high speed passenger train.Vehicle selection is container flat car Xik.Container transport with its standards,safety and high efficiency is the inevitable choice for quick transportation,There are there options of draft gears for high-speed freight train.The first one is MT-3 which is the main type buffer of general-purpose freight cars.the second is elastic clay that has been included both in UIC and AAR standards,and now,it has been used in our quasi-high speed passenger train.Practice proves it works well.the third is Hydro-pneumatic which is the ideal draft gears.It uses the nitrogen as the recovery spring,as a result,it achieves wear-free during the work and improve the die longevity greatly.That is one orientation of the future railway vehicle draft gears.2.The foundation brake rigging device of the high-speed wagon,according to the research of many scholars,can be identified as brake discs.its brake valve is still in development,thus in this paper,F-8 type value which is equipped in the quasi-high speed passenger train and 120 value which is the main type value for our freight train were simulated and calculated.3.Creating dynamic calculation models.MT-3 and elastic clay buffer are found by the envelope linear fitting results of drop hammer tests at different heights.The hydro-pneumatic buffer is based on the precision calculation models of fluid mechanics and thermodynamics by LI Fu and HUANG Yun-hua.At the same time,writing one to one shunting impact program,then,research on the performance of the three type draft gears.4.According to the longitudinal dynamics theory,writing Matlab program,the high-speed freight train is simulated and calculated during starting and emergency brake conditions. With the simulation results,the performance of three draft gears and two brake valves are comprehensively evaluated.