Research On Dynamic Model Of HM-1 Draft Gear Based On Impact Test

The development of heavy-load transportation is an inevitable choice for maximizing railway efficiency.Railway locomotives and vehicles have become one of the most important transportation equipment for passengers and freight transports.Since the Da-Qin Line has opened a 10,000-ton heavy-load trains,China has made considerable progress in heavy-load transportation.The development of heavy-load transport is trend of the times,and the performance of draft gear devices are closely related to transport efficiency.As the axle weight of the vehicle increases and the number of formations increases,and the vehicle-to-vehicle coupler force also begins to increase,especially when the vehicle is in transitional condition.The vehicle transits from one state to another in a short period of time.At that time,the coupler force increases dramatically.A series of serious problems will arise in the course of operation,such as excessive longitudinal shock vibration and breakage of the coupler,so as to reduce the transportation efficiency.This has also encouraged a large number of scholars at home and abroad to conduct in-depth studies on the longitudinal dynamics of heavy-load trains.This paper starts with the buffer mechanics model.Based on the impact test data of the HM-1 draft gear,the impedance characteristics of the draft gear are analyzed.Because of the measured data,the sample point have a large capacity and a strong discrete type,so the data should be processed.Firstly,selecting the displacement and the corresponding coupler force data when the draft gear is loaded at the same speed level;Then,adopting a polynomial fitting method,and obtaining the characteristic points on the draft gear impedance characteristic curve;Finally,Piecewise Linearization methods are used to describe the draft gear impedance characteristics at different impact speeds.According to the relationship between the mechanics models of the draft gear,linear data interpolation method and triangle-based linear interpolation method are used to establish the draft gear data grid model.This model contains the coupler force(impedance)relationship of the draft gear at any compression speeds and displacements.According to the test process and mechanics theory of a vehicle impacting a vehicle,the longitudinal dynamic differential equations of one-to-one impacting of freight vehicles are established.The variables such as displacement,velocity and acceleration of the two vehicles during the impacting process are obtained by a simple iterative method.The vehicle impacting test numerical simulation programs are written in Python language,and the impact speeds and displacements of the impacting vehicle are input.When the draft gear data grid model are called,the data grid are interpolated by RBF(radial basis function)interpolation method.The impedance characteristics of the draft gear obtains by the simulation basically agreeing with the test curve.Comparing the simulation results with the test results,the relative errors of the maximum displacements generated by the draft gear are within 5%,and the relative errors of the maximum coupler force that the draft gear absorbs are within 5%,thus verifying the draft gear.The effectiveness of the data grid model.This work has important guiding significance and reference value for the performance,designing or optimization,application and researching and development of HM-1 draft gear.