| Wheel polygon is a special form of wheel out-of-roundness(OOR)of high-speed train,which shows that the radius of wheel changes periodically along the whole circumference direction.Wheel polygon of high-speed train will deteriorate the dynamic interaction of wheel and rail,intensify the vibration of vehicle-track components,affect the reliability of those components and train safety,which has been widely concerned by manufacturers,application departments and scholars.In order to grasp the present situation of wheel OOR of high-speed train in China,study the influence of wheel polygon on vehicle dynamic performance,further analyze the vibration response of wheel polygon,realize the early diagnosis and identification of high-order polygon,and improve the controllability of wheel polygon problem,the main works in this dissertation about the above problems are as follow:1.Analysing the wheel OOR test data bofore and after wheel reprofiling and wheel polygon tracking data of various types of high-speed trains in China,the distribution of polygonal characteristic parameters and the variation of parameters with operating mileage were analyzed.The results show that the degree of wheel OOR can be effectively reduced by wheel reprofiling,and the degree of wheel OOR deepens with the increase of train mileage.At the same time,the occurrence frequency of wheel polygon of different types of vehicle is different,and it is often difficult to detect and control in time.2.Aiming at a high-speed train with serious wheel polygon problem,the whole vehicle dynamic simulation model of high-speed train is established,using the simple harmonic function of wheel diameter to describle the wheel polygon,and the influence of wheel polygon on the vehicle dynamic performance is studied.The simulation results show that the high-order wheel polygon will reduce the critical speed of the vehicle system,resulting in severe wheelrail interaction and large vertical vibration of axle box.3.In order to better analyze the vibration response and vibration characteristics of axle box in wheel polygon situation,the flexible body model of wheelset is developed,and the vibration response and characteristics of vehicle system considering the flexible deformation of wheelset are analyzed.The simulation results show that the structural deformation of the wheelset in the rigid-flexible coupling model will be stimulated during the vehicle operation,and the random irregularity of the track will intensify the high-frequency vibration of the wheelset,so that the vibration of the axle box is larger and the frequency component is more complex than that of the rigid model.4.In order to preferably monitor and control the wheel polygon problem,an intelligent diagnosis and identification method for high-order wheel polygon is proposed based on the vibration acceleration response of axle box.The vertical vibration data of axle box are processed by CEEMDAN,the effective IMF is selected by K-L divergence,and the existence and order of highe-order wheel polygon are deduced by combining the fault characteristic frequency of polygon.Finally,the validity,accuracy and parameter adaptability of the method are verified by rigid-flexible coupling simulation and line test data,and the feasibility of early warning of high-order wheel polygon is also verified. |
