Research On Rail Grinding Profile Design And Adaptability Of Curved Section

In recent years,with the continuous increase of railway operation mileage in China,many small radius curve sections have emerged to adapt to the complex and changeable geographical environment conditions.The wheel-rail relationship in the small radius curve section is extremely complex,the rail wear damage is extremely serious,and the rail operation and maintenance situation is the most severe.In recent years,the rail wear problem in the small radius curve section has become one of the urgent problems to be solved.At present,rail grinding is the main means to effectively solve the rail disease,which can prolong the service life of the rail.Although the grinding technology in China is gradually mature,the same target profile is still used in different sections of the curve section,resulting in a large amount of grinding.Whether the grinding target profile is reasonable or not directly affects the rail grinding effect.Therefore,the design of rail grinding profile for different sections of curve section is of great significance to solve the problem of abnormal wear of rail,optimize the wheel-rail relationship and improve the service life of rail.On the basis of summarizing the research of relevant experts and scholars at home and abroad,this thesis investigates the rails in the curve section of an intercity line.Taking the measured worn rail profile as the research object,a multi-objective optimization design method of rail profile based on differential evolution algorithm is constructed.The rail grinding target profile suitable for different sections of the curve section is designed,and the adaptability of the profile is analyzed,which provides a reference for improving the wheel-rail relationship,prolonging the service life of the rail in the curve section and reducing the cost of railway operation and maintenance.The main work and conclusions of this thesis are as follows:(1)The dynamic model of CRH2 vehicle is established,and the evolution law of rail wear and dynamic response in different sections of curve section are systematically analyzed.It mainly includes the rail wear distribution characteristics and wear development law of the inner and outer rails in the transition curve section and the circular curve section,as well as the dynamic evolution law of the worn rails with different throughputs.(2)The cubic NURBS curve description method of rail profile and the bicubic NURBS surface description method of rail are constructed.Combined with this method,an optimization design method of rail profile is proposed,which takes reducing the amount of rail grinding and improving the distribution uniformity of wheel-rail contact points as the optimization goal and takes the upper and lower boundaries of rail profile,profile concavity and convexity,and vehicle dynamic performance as constraints.The differential evolution algorithm is used to solve the rail grinding profile at different positions of the curve segment.At the same time,based on the bicubic NURNS surface theory,the three-dimensional surface fitting of the variable cross-section grinding profile near the slow circle point is carried out.(3)The grinding profile designed and standard grinding profile are compared and analyzed from many aspects,and the rationality of the optimization design method is verified.The advantages and disadvantages of grinding profile designed are evaluated mainly from the aspects of the rail grinding amount,wheel-rail static contact geometry and vehicle dynamic performance.By establishing an elastic-plastic wheel-rail finite element model,the contact mechanical properties of design grinding profile and standard grinding profile under different wheelset lateral displacements are compared and studied.It is found that the rail grinding amount of the grinding profile designed is greatly reduced,the wheel-rail contact geometry is significantly improved,and the dynamic performance is significantly improved,which is beneficial to slow down the rail wear in the curve section and prolong the rail maintenance cycle and service life.(4)The adaptability of the grinding profile designed is analyzed from many aspects.Through the research on the adaptability of running speed,track parameters and worn wheels,it is found that within the scope of the parameters discussed,the dynamic performance of the grinding profile designed is significantly improved under different driving speeds,curve,and rail bottom slopes.When matched with wheels in different wear stages,the dynamic indicators of the grinding profile designed are within the limits.