Optimizing rail profiles to improve metro vehicle-rail dynamic performance considering worn wheel profiles and curved tracks

The LM wheel profile and profile of Chinese 60 kg/m rail (LM&CHN60) are commonly used in the Chinese metro. However, the poor matching between wheel and rail profiles as well as the instability of the vehicle often occur on some curved sections due to wear. Therefore, it is necessary to design compatible rail profiles for the worn wheel profiles as a replacement for the old rail in these sections. This paper first presents the analysis of using the worn wheel and rail profiles as well as LM&CHN60 with a three-dimensional vehicle-track coupled model. Then, an optimization of the rail profiles for the worn wheel profiles is implemented in terms of both worn and unworn profiles, which is not only to improve the stability of the vehicle but also to minimize the rail wear by taking the curve performance into consideration. An inverse design method is proposed for rail profile design to improve the wheel–rail contact properties. Then, the wear of the optimized rail profiles is calculated with two types of track, which is the basis for selecting the optimal profile of a specific curve. Furthermore, the evaluation of the vehicle-track dynamic behavior with optimum rail profiles is also performed by comparison with the worn rail profiles. The entire design process is completed in a procedure programmed in MATLAB. The application of the optimized rail profiles significantly slows down the growth rate of rail wear. Additionally, the maintenance intervals for rail reprofiling have been doubled.