Research On High-Speed Emu Wheel Profile Optimization

With the raising of train speed, wheel/rail wear problem becomes more and more serious in the high-speed railway system. The wheel profile has a direct and important impact on wheel/rail wear. Optimized profiles can improve the wheel/rail matching performance to reduce wheel/rail wear and related maintenance costs. In order to improve the wheel-rail matching performance and reduce the wheel/rail wear thus extending the service cycle of wheel, the wheel profile optimization design is studied in this thesis focusing on the wheel profile of a certain EMU running in China. The main work of this thesis and its achievements are summarized as follows.Firstly, the methods employed in this thesis to solve the wheel/rail matching performance parameters, the wheel/rail interaction and vehicle system dynamics are introduced to establish the theoretical basis for wheel profile optimization.Secondly, the measured wheel/rail wear of several high-speed EMU commonly used in China is analyzed, and the main reason of wheel failure for the certain EMU in the thesis is found out, being the serious flange wear. In order to indicate the direction for wheel profile optimization design, the contacting performance and vehicle dynamic performance for the wheel with flange wear are calculated, and the influences of vehicle suspension parameters on the vehicle straight lines performance and cure negotiation performance are analyzed.Finally, an improved parallel inverse design method, in which the goal curve be obtained by automatic search with a numerical optimization algorithm is proposed and applied to optimize the wheel profile by taking the rolling radius differences as the goal curve for the purpose of reducing the wheel flange wear.The results of the numerical analysis show that, compared with the initial wheel profile, the rolling radius difference of the optimized profile is increased when the wheel displacement is within the range of 0-9mm, and this implies that the optimized profile can effectively reduce the wheel flange wear under the condition of sharp curve. At the same time, the good passing performance on straight track and the large radius curve are ensured.Vehicle dynamic analysis in this thesis is completed by means of the software SIMPACK. The calculation of contacting performance is implemented based on the Kalker’s 3-dimensional non Hertz rolling contact theory by using the software MATLAB. The wheel profile optimization design based on the improved parallel inverse design method is completed also by utilizing the software MATLAB.