Influence Of Tread Wear On Vehicle Dynamic Performance And Analysis Of Positioning Node Of Axle Box Rotating Arm With Variable Stiffness

The rapid development of high-speed trains in China has become one of the mainstream travel modes for people.However,with the increase of train speed and operating mileage,wheel-rail wear has also caused a series of dynamic problems.A series of kinetic problems have been solved.Some EMUs(Electric Multiple Units)have different characteristics of snake instability in the operation process,such as car body shaking with small taper(the primary-hunting)and bogie alarm with big taper(secondary-hunting).These instability phenomena can affect the comfort of passengers in the slightest,and it can easily lead to the derailment of the train.Aiming at the hunting instability of current high-speed trains in the tread wear stage,this paper mainly studies the influence of tread wear on the dynamic performance of high-speed trains.The simulation reproduces the hunting instability of the car body and the bogie,and studies the positioning node of axle box rotating arm with variable stiffness to restrain the hunting instability The main research contents of this paper are as follows:(1)Taking a certain type of domestic 380 km EMU train as the object,the dynamic analysis software UM(Universal Mechanism)is used to establish a high-speed train dynamics model.The model considers Hertz-type wheel-rail contact,nonlinear suspension parameters,and China’s high-speed track irregularities.Through numerical simulation,the validity of the model is verified.(2)Research the basic parameters of wheel tread,such as wheel rim height,wheel rim thickness,and the influence of wheel rim comprehensive value.The influence of tread wear under different mileage on vehicle dynamics performance is studied.According to the mechanism of the vehicle’s primary and secondary hunting,the phenomena of abnormal car body shaking and abnormal bogie vibration are simulated and reproduced,and the vehicle response and hunting characteristics of the corresponding working conditions are analyzed.(3)Carry out the sensitivity analysis of the model suspension parameters to the dynamic performance,and determine the key suspension parameters that affect the hunting motion.Based on the PT(Poynting-Thomson)model,the variation range of the longitudinal rigidity of the axle box boom node is taken as the optimization object,and the rms value of the lateral acceleration of the vehicle body when the primaryhunting occurs and the rms value of the lateral acceleration of the frame when the secondary-hunting occurs both reach the minimum as the optimization objective,Using genetic optimization algorithm for multi-objective optimization.Numerical simulation is used to analyze the suppression effect of the optimized variable-stiffness boom joints on the primary and secondary hunting instability.The research results show that: tread wear has a great influence on the running safety,lateral stability and riding comfort of the train.Poor wheel-rail profile matching can easily lead to primary and secondary hunting instability.The variable-rigidity boom node can inhibit the car body and the hunting instability of the frame has a certain effect,and the research results of the thesis have certain theoretical and practical significance for the design and optimization of the positioning node of the axle box rotating arm.