Multi-Objective Optimization Of Wheel Profile Of CRH1 EMU Oriented To Flang Wear Control

Wheel wear is one of the main problems that affect the safety and stability of high speed trains and it also affects the service budget in China. Wheel wear will degrade the dynamic performance of the vehicle, and influence the comfort level of the train. In order to improve the wheel/rail matching performance and reduce the wheel flange/rail wear to extend wheel running mileage and drop the operating costs, the thesis focuses on the wheel profile optimization design aiming at severe wheel flange wear with CRH1 EMU after changing the wheel profile. The major works of this thesis are summarized as follows.1. Based on the theory of vehicle system dynamics, the dynamic simulation model of CRH1 EMU is established with SIMPACK software. The dynamic performance indexes and evaluation criteria of the vehicle system are given to verify the correctness of the dynamic model. And the foundation for follow-up study is laid.2. To solve the severe wheel flange wear problem with CRH1 after changing the wheel profile which could be found from test data of the wheels, the contact performance for LMA and LMD wheel profiles on CRH1 EMU is analyzed respectively with CONTACT program, based on the Kalker’s 3-dimensional non Hertz rolling contact theory. The dynamic performance of the vehicle is also calculated. The main factor causing the flange wear is found, which provides significant basis for the optimization design of wheel profile.3. The multi-objective optimization of wheel profile of CRH1 EMU orienting to flange wear control is studied. An optimization model is established with MATLAB software. In the optimized model, the lateral force and attack angle that reflect the performance through small radius curve along with the lateral acceleration of car body that reflect the performance on straight track, are taken as the objective functions. The wheel geometric constraints and the dynamic performance parameters such as safety, serving as constraint condition. An improved particle swarm optimization algorithm, in which the dynamic adjustment of the accelerating factor enhances the convergence speed, is proposed to solve the optimization model problem. At the meantime, to avoid the appearance of irregular wheel profile, a wheel profile curve base is established. The optimization results show that, the optimized wheel profile reduces the wheel flange wear effectively by decreasing lateral displacement, attack angle and lateral force; the critical speed on straight track and the ability of going back to track central position of wheel set were improved. The optimized wheel profile enhances the capacity upon small radius curve and relieves the wheel flange wear, in the process of ensuring the vehicle performance on straight track and large radius curve.