Wheel-Rail Adhesion And Dynamic Interaction Of Heavy-Haul Locomotive Under Traction Condition By Wheelset Rigid And Elastic Modeling

With the continuous development of heavy haul railway transportation in China to improve the running speed and increase the carrying capacity,the safety and stability of vehicle operation have become the focus of public attention.Harmony high-power electric locomotive is the main traction equipment on the heavy haul transportation line in China.As the locomotive runs faster and longer,it will also be affected by bad weather such as wind and sand,rain and snow during operation,so that the safety of locomotive operation can not be effectively guaranteed,and it will also affect the abnormal vibration,wheel-rail damage and wheel-rail wear of various parts of the locomotive.In view of this,based on the dynamics of locomotive and vehicle system,this thesis takes the harmonious six-axle heavy-duty electric locomotive as the main research object,and studies the dynamic characteristics of rigid-flexible coupling locomotive considering flexible wheelset,as well as the dynamic behavior analysis of wheel-rail contact creep limit and the matching relationship between wheel wear evolution law and friction coefficient of rail top and rail side.Firstly,according to the three-dimensional structure of the locomotive wheel set,the flexible wheel model is established by using Hypermesh and Ansys finite element analysis software through the modal superposition method,and then the rigid-flexible coupling locomotive dynamics model and multi-rigid body model are established by using the multi-body dynamics simulation analysis software UM.And the wheel-rail lateral force is compared with the measured data,which verifies the correctness of the model.At the same time,due to the elastic effect of the wheelset,the nonlinear critical speed of the locomotive can be reduced by more than 10 % compared with the rigid wheelset.Then,considering the influence of the flexible structure of the wheelset on the dynamic performance of the locomotive,the dynamic indexes such as derailment coefficient,wheel load reduction rate and wheel-rail force are compared and analyzed.It is found that the trend of the dynamic indexes corresponding to the rigid and flexible modeling is basically the same,but due to the deformation and elastic vibration of the flexible body structure,the amplitude of the dynamic indexes of the flexible wheelset is slightly smaller than that of the rigid wheelset.The flexible wheelset has elastic deformation inside and can reduce the impact of the rail on the vehicle.Therefore,the amplitude of the vibration acceleration of the flexible wheelset is about 20 % smaller than that of the rigid wheelset.Because the suspension system of the locomotive vehicle has a good vibration isolation effect,the vibration acceleration at the body and frame is also smaller than that at the axle box of the wheelset.Further,the dynamic behavior of wheel-rail contact creep under locomotive traction is analyzed.The results show that the locomotive is basically in an adhesive state when running on a straight line.When passing through a small radius curve of 300 m and 600 m,the wheel-rail force is easy to reach the creep limit state and the full sliding phenomenon occurs.At this time,the synthetic creep force is equal to the limit friction force,but it is difficult to reach the full sliding state when the locomotive passes through a curve with a larger radius of 1200 m.The wheel is also between the two states of adhesion and sliding.As the traction force increases,the area of the contact spot in the adhesion zone also increases,but the change is not obvious for the rigid wheelset.The contact spot area amplitude of the flexible wheelset is larger than that of the rigid wheelset,and can even exceed more than 30 % of the rigid wheelset.Because the volume wear can be calculated by the wear power,the wear power of the rigid and flexible wheelset is compared.It can be inferred that the wheel wear is about 20 % smaller than that of the rigid wheelset when considering the flexibility of the wheelset.Finally,the influence of constant friction coefficient on the evolution law of wheel wear is analyzed,and different friction coefficients of rail top and rail side are selected to summarize its influence on wheel wear depth.When the rail top friction coefficient is constant,the greater the rail side friction coefficient,the greater the wheel wear;when the friction coefficient of the rail side is constant,the wear depth of the wheel increases with the increase of the friction coefficient of the rail top.In order to minimize the wheel wear,considering the traction demand of the locomotive,the more appropriate matching relationship of the friction coefficient of the rail top is : the friction coefficient of the rail top is 0.2,and the friction coefficient of the rail side is 0.05.