| With the rapid development of urban rail transit,the passenger capacity and operation speed of subway vehicles are constantly improving,the wheel-rail interworking force is constantly increasing,and the problems of attrition and fatigue are becoming more and more serious,especially in the sharp curve.Rail wear and rolling contact fatigue lead to stripping and falling blocks,which directly change the position of wheel-rail profile and contact points.On the one hand,this has a certain negative impact on the comfort and safety of train operation,on the other hand,it also greatly reduces the service life of wheel-rail and increases the cost of operation and maintenance.Therefore,on the basis of the existing wheel-rail profile,the evolution of the rail profile and the contact fatigue development law of the two commonly used subway vehicles under different wheel-rail matching conditions are obtained through the simulation calculation of the multi-body dynamics software.It is of practical significance to provide certain reference for the urban rail operation and maintenance department.In this paper,sharp curve is used as the research method to predict the life development law of rail operation and rolling contact fatigue initiation.The main research contents are as follows:1.Based on multi-body dynamics software,two common subway vehicle models are established to analyze the development law of rail wear throughout life as well as the running stability and comfort of the vehicle body under the combination of various wheel tread,standard rail surface and rail surface with a certain degree of wear.Based on the above two factors,the optimal wheel-rail matching combination in the sharp curve is obtained,which provides the corresponding reference scheme for the subway line design and selection.2.Based on multi-body dynamics simulation software,this paper calculates and analyzes two kinds of tread,LM and S1002,which have different wear development rate when combined with type 60 rail,and analyzes the influence of track parameters on the size of rail equivalent stress and the position,depth and size of rolling contact fatigue that is most likely to occur under different wheel-rail combination.Considering the stress and contact fatigue initiation,the optimal wheel-rail combination and the optimum track setting parameters were selected,and the fatigue initiation of rail under the two tread combinations was compared to analyze the relationship between wear rate and contact fatigue initiation.The main conclusions are as follows:(1)Under the same working condition,the development of upper side grinding of outer rail is divided into three stages,and the development of vertical grinding is divided into two stages.The first two development stages of side grinding are relatively slow,and the development period coincides with the first development stage of vertical grinding.The last stage of wear develops very rapidly,which affects the service life of the rail.Among them,LM-60 N has the shortest service time in the sharp curve section of metro.The wheel and rail lateral force,derailment coefficient,wheel load reduction rate,vertical acceleration and lateral acceleration of the train body increase significantly after the 60 N surface is worn.Considering the rail profile under the two conditions of XP55 tread matching from the perspective of running stability,the comprehensive evaluation index of stability is better among the three.Starting from the running comfort of the car body: S1002 tread is matched with the rail profile of the two states.The acceleration of the car body is the smallest among the three and the increase is the lowest.(2)Contact fatigue decreases with the increase of radius under different wheel-rail combinations,but the maximum fatigue on the outer rail is slightly lower than that on the inner rail under the same combination.The rolling contact fatigue value decreases with the increase of the friction coefficient.When μ is less than 0.3,the outer rail fatigue value is greater than that of the inner rail,but the inner rail exceeds the outer rail with the increase of the friction coefficient.The bottom slope of 1:20 and 1:40 rails is more unfavorable to the development of contact fatigue.Under the condition of the same tread combination and curve radius,the fatigue initiation range of 60 D and 60 N profiles is larger than that of CN60 and UIC60.Considering the contact fatigue initiation and equivalent stress,the latter two profiles are more suitable for use in the small curve radius of the subway.(3)The development law of rolling contact fatigue of LM tread is similar to that of S1002 tread under the same working condition,and the fatigue value of S1002 tread under the same working condition is greater than that of LM tread.According to the results in Section 3,it can be seen that faster wear rate has an inhibiting effect on the development of rolling contact fatigue,under the working conditions of simulation calculation,S1002 is better combined with CN60 and UIC60. |
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