| In recent years,with the rapid development of high-speed and heavy-duty railways in China,the contact fatigue between train wheel-rail has grown in intensity.For example,the car body will shake at high speed when a train passes through the region of rail fatigue.If it cannot be discovered and processed in time,it will affect the passenger's riding comfort and even the train's operating safety.Therefore,the study of the wheel-rail contact relationship and contact fatigue of the train is of great significance to the safe operation of the train.Through field investigation,it is found that vehicle axle load and rail corrugation have great influence on rail fatigue.Therefore,by taking the high-speed comprehensive inspection vehicle,the rail section with corrugation wear in a high-speed railway in China is actually tested by rail profile measuring instrument,and the data of geometric parameters of corrugation section are collected.Based on the measured data,the rail finite element model with corrugation is established,the rail stress and strain under different axle loads are calculated,and then the No The influence of the same parameters on rail fatigue life.The specific research work is reflected in the following aspects:(1)Firstly,three-dimensional models of wheel set,rail and track plate are established according to the actual geometric parameters.The type of tread is LMA wearing tread,the rail is 60kg/m,the type of rail plate is CRTS-?,and the ratio of rail bottom slope is 1:40.The key area of wheel rail rolling contact and fatigue studied in this paper is mainly located in the contact area,so the mesh of contact area between wheel set and rail should be refining.The transition mesh is divided from the refined mesh of the wheel-rail contact part to the large mesh of the rim part without affecting the accuracy of the calculation results,which is in order to reduce the number of mesh,and then improve the efficiency.(2)Secondly,a three-dimensional rolling contact model of wheel-rail is established based on finite element method to obtain the rolling contact state.The paper focuses on the influence of the axle weight and the wavy wear(the unilateral rail)on the wheel-rail during the steady rolling contact.The results show that the contact stress and the maximum equivalent plastic strain of the rail are increased with the increase of the axle weight.In addition,the maximum contact stress and strain of the rail are located on the sub-surface about 3mm deep.(3)When the rail is located in the wavy wear section,the contact stress and strain are larger than the normal section.When the wheel passes through the wave-grinding section(one side of the rail),the vibration between the wheel-rail leads to unstable contact,which makes the contact zone wavy,the other side of the rail is excited by vibration shock of high-speed wheel-rail,which finally causes rail wave wear on the other side of the rail.(4)Finally,the fatigue crack initiation life was estimated by damage function,and the influence of axle weight and the unilateral rail wave wear on the fatigue crack initiation life of the rail was studied with the results of the wheel-rail rolling contact model.The results show that the fatigue life of the rail decreases gradually with the increase of axle weight,but the decrease rate slows down gradually.Moreover,the rail wave wear phenomenon will greatly reduce the rail life. |
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