| Wheel out of roundness will have a bad impact on vehicle dynamic performance,deteriorating wheel-rail force and causing severe vibration of vehicle-track system.High-frequency vibration will occur in the running process of high-speed train under wheel high-order polygon,which will cause fatigue damage to rail and wheel tread,fatigue cracks and uneven wear and so on,resulting in great noise pollution.When studying the influence of wheel polygon on the vibration of the wheel-rail system,the rigid body model can not accurately reflect the vibration of the wheel-rail system.Even considering the elastic deformation of a single component,it is still difficult to accurately describe the overall vibration characteristics of the wheel-rail system.Thus,it is necessary to establish a rigid-flexible coupled vehicle-track dynamic model to analyze the elastic vibration characteristics of each part of the wheel-rail system.Based on the dynamics theory of rigid-flexible coupling system,the rigid-flexible coupling dynamic model of the whole vehicle-track system is constructed by using the multi-body dynamics software SIMPACK.The vibration caused by high-order polygonal wheels is analyzed.The main research contents include:(1)A rigid-flexible coupling dynamic model of vehicle-track system is constructed,including rigid bogie frame and car body,and flexible wheel-rail system composed of flexible track,wheelset(including brake disc),bearing and axle box.The track excitation uses the measured Wuhan-Guangzhou track spectrum.(2)The effects of different speed,polygon order and wave depth on the wheel-rail force,bearing force and vibration characteristics of rail,track slab,wheelset,brake disc and axle box are analyzed.The effects of polygon excitation frequency on excited modal of various parts of wheel-rail system are studied.(3)The vibration transmission relationship between rail and track slab,axle and brake disc is studied.The results show that the frequency components similar to the structural modes,coupled modes and combined modes of the track plate are amplified when the vibration is transferred from rail to track slab,and the frequency components similar to the structural modes of the brake disc are amplified when the vibration is transferred from axle to brake disc.(4)Comparing the simulation results with the test data,it is found that there are polygonal excitation frequencies in the vertical acceleration of axle box.And there are also structural modes of wheelset and track slab and polygonal excitation frequencies in the lateral vibration of brake disc,which verify the correctness of the model.(5)Axle disc braking unit is added to simulate the emergency braking and maximum common braking conditions.The influence of braking conditions on lateral vibration of brake discs is analyzed and the vibration characteristics of brake discs at different parts are compared.The results show that the lateral vibration decreases when braking is applied,and the excited mode on the brake disc disappears basically,but the brake disc bears a large lateral restraint force and tangential force. |
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