Study On The Dynamic Performance Of A Wide-gauge Six-axle Heavy Locomotive By Considering The Elastic Characteristics Of Wheelsets

At present,the railway transportation is developing towards the directions of heavy duty and high speed.In the whole world,the heavy-duty transportation technology has been regarded as the mainstream development direction of freight railway transportation.With the increase of the freight weight and running speed of heavy-duty locomotives and the great improvement of the design requirements,fully considering the elastic characteristics of the wheelsets plays an important role in the study of the dynamic performance of locomotives;at the same time,the study of the elastic characteristics of wheelsets is one of the effective means to study the characteristics of polygonal wheels.This paper takes a six-axle heavy-duty wide-gauge freight locomotive as the research object.The type of bogie is Co-Co with the axle load of 25 t.The vehicle has the characteristics of soft primary suspension and stiff secondary suspension.Firstly,a multi-rigid body dynamic model is established by using SIMPACK software,which includes a total of 29 bodies,and each bogie includes six springs and shock absorbers in the vertical direction in primary suspension.After that,a rigid-flexible coupling model of the locomotive with flexible wheelsets is established;the wheelset and the large gear are considered as a whole.Pre-processing and meshing are performed in Hyper Mesh.Then the ANSYS software is used and the main nodes are extracted.The finite element sub-structure modal analysis is carried out in ANSYS software.And the main-node finite element model is imported to SIMPACK software to generate the elastic wheelset sub-structure model.Finally,the vehicle rigid-flexible coupling dynamics model is established.By superimposing a short-wave irregularity on the five-level track spectra of the United States as the track spectrum excitations,the vibration response characteristics of the vehicle at different speeds and lines are analyzed.The dynamic performance of the vehicle is mainly studied according to the ГОСТP55495-2013.By comparing the simulation results of multi-rigid body and rigid-flexible coupled vehicle models,it is concluded that the elastic wheelset can alleviate the vibration and impact between the wheel and rail,so that it has the effect of reduction of the wheel-rail force to a certain extent.The elastic wheelset has a greater influence of the lateral vibration response characteristics of the vehicle.The nonlinear critical speed of the rigid-flexible coupled vehicle model is lower.And especially at high speeds or under curvilinear conditions,the influence of elastic wheelsets on vehicle dynamic characteristics and safety is more obvious.Therefore,it is necessary to consider the elastic characteristics of the wheelsets when studying the medium-and high-frequency characteristics and curvilinear conditions of the vehicle.Finally,based on the harmonic function to describe the wheel non-smoothness,a polygonal wheel model is established.The influence of the amplitude and order of the polygonal wheel is analysed on the vehicle dynamic performance at different vehicle speeds.The results show that when the excitation frequency caused by the polygonal wheel is close to the natural frequency of the vehicle structures,resonance will occur and the vehicle vibration will be aggravated.In the design speed range of 120km/h,the influence of the polygonal wheel on the locomotive safety and vehicle dynamic characteristics is closed related to the modal characteristics of the vehicle system.Besides,it has little effect on the running comfort.