Multi-Objective Optimization of Rail Pre-Grinding Profile in Straight Line for High Speed Railway

摘要

In order to modify the rail pre-grinding profile smoothly,non-uniform rational B-spline(NURBS)curve with weight factors is used to establish a parameterized model of the profile.A wheel-rail contact stochastic finite element model(FEM) is constructed by the Latin hypercube sampling method and 3 D elasto-plastic FEM,in which the wheelset's lateral displacement quantity is regarded as a random variable.The maximum values of nodal accumulated contact stress(NACS) and nodal mean contact stress(NMCS) in different pre-grinding profiles with differential weight factors are calculated and taken as the training samples to establish two Kriging models.A multi-objective optimization model of pre-grinding profile is established,in which the objective functions are the NACS and NMCS Kriging models.The optimum weight factors are sought using a non-dominated sorting genetic algorithm II(NSGA-II),and the corresponding optimum pre-grinding profile is obtained.The contact stress calculation before and after optimization indicates that the maximum values of NACS and NMCS decline significantly.