Research On The Optimization Of Railhead Profiles On Curve Tracks Of Metro

Wheel-rail wear is one of the important sources of causing rail transit diseases,which seriously affects the safety of vehicle operation,shortens wheel-rail maintenance interval and the service life of wheels and rails,and increases the operation and maintenance cost of rail transit system.Wheel-rail wear is closely related to the wheel-rail contact geometry and the dynamic characteristics of vehicle operation,and one of the effective methods to reduce the wheel-rail wear is to optimize the rail profile.In this paper,a rail profile optimization method with the objective of minimizing wear by using measured profile is established,which includes vehicletrack system dynamics sub-model,optimization target sub-model,profile parameterized submodel and profiles optimization iterative sub-model.Then,vehicle parameters and rail profiles(high and low rail)measured on field are selected as input parameters,and the optimization design method is applied to optimize profile and a set of optimal profiles is obtained.In the process of rail profile optimization,the iterative evolution process of rail-wheel wear,contact geometry and vehicle operation indexes are studied.And the matching analysis of the optimized rail profile with the running speed,track structure and vehicle parameters are carried out.The main work and conclusions of this paper are as follows:1.The wear state of the wheel-rail profiles measured on the field in a metro are analyzed,and the characteristics and rules of wheel-rail profile wear on curved track of this metro line are mastered.It is found that the lateral and vertical wear of curved rail are serious,and there is asymmetry between the high and low rail.At the same time,the field measurement also provides basic data for rail profile optimization.2.The optimization design method of curved rail profile is established,which includes the vehicle-rail system dynamic sub-model,the optimization target sub-model,the profile parameterization sub-model and profile optimization process.Among them,the optimization objective sub-model takes minimization of wheel-rail wear as the optimization objective,and takes the vehicle running safety index as the constraint condition.The profile parameterized sub-model is to construct rail profiles using the improved NURBS method.The profile optimization process firstly describes the curve rail profile with chromosomes,firstly calculates the individual fitness,then geometrically describes and updates the profile,and finally,according to the termination condition of genetic iteration,the optimized design profile is obtained.3.By using the curve rail profile optimization design method and taking the measured vehicle parameters and rail profiles as the input parameters,the curve rail profile was optimized and iterated under specific conditions,and the optimal rail profile meeting the objective function was obtained.The iterative evolution process of wheel-rail wear,contact geometry and other vehicle operation indexes in the optimization process are studied.The results show that the optimized profile can significantly reduce the wheel-rail wear and contact stress,ensure the safety and stability of vehicle operation,and improve the wheel-rail contact geometry.4.The matching of optimal profile with running speed,track structure and vehicle parameters are analyzed.The results show that the matching result of the optimal profile is better than that of the standard profile within the parameters studied in this paper.