Multiobjective optimisation of rail profile at high speed

In this paper, a multiobjective optimisation method considering the rail profile at high speed is presented. Based on nonuniform rational B-spline (NURBS) theory, a parameterised model of the rail profile is constructed to determine the variables. The wear index, wheel–rail lateral force and contact stress are selected as the objective function. Based on multibody dynamics theory is applied to establish the vehicle–track coupling dynamic model of the high-speed train CRH380A. An improved NSGA-II algorithm called CN-NSGA-II is proposed in this study. The multi-objective optimisation problem of rail profile is improved by the vehicle–track coupling dynamics model and CN-NSGA-II algorithm. The Pareto front solution is calculated, and the TOPSIS algorithm is used to select the optimal solution and obtain the optimised profile. The analysis of the objective function values of the CN60 profiles and the optimised profile indicate that the maximum wheel–rail lateral force of the left and right wheels of the steering wheelset decreases by 13.3% and 13.71%, the maximum contact stress decreases by 10.35% and 3.21%, and the maximum wear number decreases by 36.09% and 11.4%. The new optimised rail profile can effectively reduce the wheel–rail lateral force, contact stress and wear number in high-speed running conditions.