| With the development of high speed railway, the interaction of wheel/rail system is more intense. The influence of wheelset’s rotating and its structure elastic on dynamic performance such as safety, vibration, contact and curve passing can not be ignored. In this paper, the vehicle-track system dynamic model which considered rotating and elastic of wheelset was established based on high-speed EMU. Further studies are carried out about the variation rule of wheel/rail contact, interaction, additional power with the rotating and elastic deformation of wheelset, the vibration of vehicle system,curve passing and wear, the operation safety of vehicle and the fatigue performance of wheel/axle fitting area with the impact of wheel defects. The main contents of this thesis are as follows:(1)The elastic-rigid coupling dynamic model of vehicle-track system was established with the elastic processing of wheelset based on the rotating Timoshenko beam, and the elastic dynamic model which considered modals of all components was also established by using finite element software and multi-body dynamic software. The tangent operation performance of vehicle system is analyzed by using these models. The results show that, the models can accurately reflect the dynamic performance of vehicle system and vibration characteristics of rotating wheelset compared with the test results.Using the elastic model can obtain more accurate results vibration transmission of vehicle system.(2)With the dynamic model considered elastic and rotating walking of wheelset,the bending deformation of wheelset, the influence of wheelset rotating on wheel/rail contact characteristics, wheel/rail forces and wheel vibration performance are analyzed when the vehicle operates in a tangent line and curve track respectively. The rotating frequency occurred in vertical acceleration of wheelset, the value and the power of which are both increased with the increasing of operation speed. The frequency domain of bogie and carbody vertical acceleration can also find the rotating vibration frequency as it transmit up to the vehicle system. The critical speed of vehicle system, the lateral position of contact points, safety index, and wheel/rail creep and wear are all affected by the different modals of wheelset. The lateral dynamics performance of vehicle system in tangent is mainly affected by the 2nd and 4th bending modal of axle and umbrella of wheel, and it is mainly affected by the axle torsion, 1st and 2nd bending modals in curve passing.(3)The deformation characteristics, the lateral displacement, the creep performance of wheelset in curve track are analyzed by using the dynamic model which considered the elastic and rotation of wheelset. The wheelset moves to the outside of curve track with the effect of Coriolis acceleration cause by eccentric and rotation. The variation of wheel/rai contact characteristics, passing safety and wheel/rail wear are obtained by the influence of passing speed, track irregularity excitation, superelevation value and radius of curve.(4)The 3D models of wheel flat defect and polygonal wear considered tread concave are established, which have truly reflected wheel tread shape in practical applications. The periodic impact of wheel tread defect on wheel/rail system are obtained by updating the wheel tread in the process of wheelset rotating. Variation of vehicle vibration and the wheel/rail force are obtained with the impact effects of different types and different geometric dimensions of the wheel tread defects. With the increase of train speed, the maximum value of wheel/rail vertical contact force increases first and then decreases influenced of wheel flat impacts, and the vibration and force are increased obviously under the impact of wheel polygonal wear. The safety limit values of wheel flat defect and the first three orders of wheel polygonal wear are obtained with the operation safety index of the high-speed train.(5)The finite element model of wheelset was built which has considered the interference fitting of wheel/axle contact area. The magnitude of interference, static load of vertical force, rotate speed of wheelset and impact of wheel defect all affect the contact stress of wheel/axle fitting area. The contact stress of wheel/axle fitting area has been reduced by the rotation of wheelset. It shouldn’t be neglected that the influence of mid-high frequency impact of wheel flats on contact stress. The Findley stress corresponding to the impact of wheel flat defect and polygonal wear is less than the fatigue limit requirement under the premise of ensuring operation safety. |
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