| The rolling contact fatigue damage is one of the important factors that affect the service life of the wheel and rail.The impact of the rolling contact fatigue damage on the wheel rail contact relationship aggravates the vibration and noise,and also affects the stability and safety of the vehicle operation.The rolling contact fatigue damage of rail is one of the main damage forms in turnout switch components.Based on the wheel rail contact probability distribution of metro,this essay studies the rail rolling contact fatigue damage and its influencing factors in Metro switch area,the main work and conclusions are as follows:(1)Firstly,by referring to the relevant literature of wheel rail rolling contact fatigue theory and experimental research at home and abroad,the purpose of studying rolling contact fatigue is further clarified,and the method of studying rolling contact fatigue damage required in this paper is selected,that is,the rolling contact fatigue damage of rail is studied through material shakedown diagram and damage function based on wear number.(2)The rigid flexible coupling dynamic model of metro vehicle turnout switch area is established.The establishment process of the model is described from three parts: vehicle dynamic model,turnout switch area dynamic model and wheel rail contact relationship.(3)Two methods for analyzing rail fatigue damage due to rolling contact are introduced.The first method is to calculate the fatigue index of the rail surface based on the material stability diagram.This method can analyze the possibility of rolling contact fatigue damage on the rail surface.The second method is based on the wheel-rail contact probability distribution,using the damage function based on the number of wear as an auxiliary method to analyze the location of the rail surface rolling contact fatigue damage.(4)According to the calculation results of rigid flexible coupling dynamic model of metro vehicle turnout switch area,the rail creep force resultant force and its angle distribution in the switch area are analyzed.The normal contact stress of curved switch rail is calculated based on three-dimensional elastic non-Hertz contact theory,and the surface fatigue index distribution of curved base rail and curved switch rail is analyzed based on shakedown diagram.(5)Based on the damage function of wear number and the probability distribution of wheel rail contact,the distribution of rolling contact fatigue damage in switch area is analyzed,and the effects of speed,axle load,internal friction coefficient and curve superelevation on rolling contact fatigue damage are compared.When the damage function based on wear number is located in zone II,the zone with high wheel rail contact probability coincides with the zone with maximum rolling contact fatigue.The cumulative damage of curved rail mainly concentrates on the track distance angle.When the rolling contact fatigue damage is accumulated at the track angle,cracks and peeling off blocks will occur.In the longitudinal direction of the line,the rolling contact fatigue damage of the curved switch rail is more serious in the section of 36mm-42 mm of the top width of the switch rail,and the most serious is at38 mm of the top width of the curved switch rail.The vehicle speed has more significant influence on the rolling contact fatigue damage of curved rail,and the axle load of the vehicle has more significant influence on the rolling contact fatigue damage of curved basic rail.With the increase of wheel rail internal friction coefficient,the wheel rail vertical force,lateral force,creep force,surface fatigue index and rolling contact fatigue damage of curved base rail and curved switch rail increase significantly.Compared with other factors,friction factor is more significant factor that affects rolling contact fatigue damage in turnout switch area. |
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