The Effect Of The High-speed Train Wheel Polygonal Wear On The Plastic Deformation Of The Rail

With the speed of the high-speed trains in China continues to increase,the force between the wheel and rail is more and more intense,which will not only affect the dynamic performance of the train,but also reduce the safety and comfort of the train and affect the passengers aboard experience,also will shorten the service life of the car body and frame,and increase the maintenance cost and replacement cost later.Firstly,this paper reviewed some common wheel-rail contact theories,then took the CRH3 high-speed train as the reference object,the multi-body dynamics software SIMAPCK was used to establish the vehicle dynamics model.Considering the influence of different depths and orders of the wheel polygon on the dynamic performance of the vehicle,the influence of wheel-rail force in the case of wheel polygon was analyzed.Finally,combined with the finite element ABAQUS software,considering the cyclic plastic ratcheting effect of rail materials,and the obtained loading spectrum under the wheel polygon was introduced into the wheel-rail excitation,the effect of dynamic loading induced by the wheel polygon on the plastic deformation of rails was discussed.The analysis results are as follows:(1)The finite element model was established under different axle loads based on the Hertz and semi-Hertz contanct theories.By coMParing the shapes of the contact spot and maximum contact pressure,it is found a significant difference according to the semi-Hertz contact theory and Hertz contact theories,it is because the curvature based on the semi-Hertz contact theory is not a constant value,which makes the shape of contact spot is not a ellipse and the peak values of contact area and maximum contact pressure is larger than the Hertz contact theory.In addition,the results obtained from contact theory and finite element method were coMPared,there is significant difference between those two methods.Therefore,in order to obtain more accurate results,the elasto-plastic finite element analysis should be carried out to obtain the plastic deformation rules of rail under wheel polygon excitation.(2)A multi-body dynamical simulation software SIMPACK was used to establish the vehicle dynamics model,and the shape of the wheel polygon was described by a harmonic function,the effects of the wave depth and order of the wheel polygon on the lateral and vertical interaction forces were discussed.Results show that,when the driving speed is constant,with the increase of the wave depth and order of the high-order polygon of the wheel,the vertical force of wheel-rail increases significantly.The low-order polygon has little effect on the interaction force when the driving speed increases from 200 km/h to 300 km/h and the wheel polygon depth is constant,the vertical and lateral force of wheel and rail increases with the increasing speed,and when the speed rises to 300 km/h,the influence of high-order polygon on the vertical and lateral forces of wheel and rail is very significant.When the wave depth and driving speed are constant,the maximum value and amplitude of lateral force of wheel and rail increase with the increasing order of wheel polygon,and increases faster when the high-order wheel polygon occurs;when the order of the polygon is located at the range of 1~10,the maximum lateral force and its amplitude decrease with the increasing driving speed;when the polygon order is high,such as 11~20,the maximum contact force of wheel and rail increases with the increasing driving speed.When the driving speed is 200 km/h,only the wheel polygon order at 17 with 0.1 mm wave depth leads to the vertical force of wheel and rail exceeds the limit;when the vehicle speed is 250 km/h,the 18 order wheel polygon with 0.05 mm wave depth,and the 14 order with 0.1 mm wave depth will make the vertical force of wheel and rail reach the critical condition;when the vehicle speed is 300 km/h,the 15 order wheel polygon with 0.05 mm wave depth and the 11 order with 0.1 mm wave depth lead to the vertical force between rail and wheel reaching the limit.In addition,the lateral force of wheel and rail under each working condition does not exceed the limit.(3)The effects of the speed,order of wheel polygon and wave depth on the derailment coefficient were calculated by using SIMPACK software.Results show that derail coefficient increases with increasing vehicle speed,but increases with the increasing order of the wheel polygon,and in a higher order,the coefficient increases faster,as well as the wave depth.But the derail coefficients in all the calculation cases are far below the limit value,which means that the CRH3 has a good performance of derailment prevention.The stability coefficient of the train was obtained by using MATLAB numerical calculation.It can be concluded that the transverse stability coefficient of the train is higher than the vertical stability coefficient,and the wheel polygon has a greater effect than the polygon order.In other words,the effect on the stationarity is more obvious;and the higher order,the more obvious influence.The depth of the polygon has a significant influence on the derailment coefficient of the train,but there is still a large allowance from the derailment coefficient limit of 2.5.(4)A 3-D wheel-rail contact model was established by using the ABAQUS software,the modified Abdel-Karim-Ohno model was selected as the material constitutive model of rails.The effect of the speed,order of wheel polygon and wave depth on the plastic deformation of rails were calculated based on a static analysis.Results show that,with the significant increase of vehicle speed and wheel polygon order,the amplitude and peak value of polygon loading spectrum increase significantly,which leads to an obvious plastic strain accumulation effect during the loading-partial unloading-reloading process,that is to say,the plastic deformation of the rail increases with the increasing speed,order of wheel polygonal wear and wave depth.The plastic deformation of rails caused by the application of the loading spectrum is significantly higher than that obtained by only applying a static axle load,but the depth of maximum plastic strain of rails does not obviously change with the change of working conditions.