| As the speed increasing of trains and bridge structure are employed in the high-speed railway, more and more attentions are paid in the study of the dynamic interaction between trains and bridges. Paritcularly, great efforts have been devoted to analysising the vehicle-bridge coupling theory and phenomena when the vehicle crosses bridges for evaluating the built bridge's function and optimizing the design of the newly built bridge. As one of the most effective and economic methods, numerical simulation is used to get precise and validity numerial value by assure the coupling relations between wheel/rail can educe the right wheel/rail force.In this thesis, the coupling thought of vehicle and bridge is applied to setting up the vehicle/bridge vibration model. On basis of characteristic of model, the most attention is pay to establishing the contact geometry relation, vertical and lateral interaction force. The process to conduce the vertical nonlinear elastic Hertz contact force and the horizontal Kalker creepage theory is presented. At the same time, the track random irregularities including vertical profile, cross-level, alignment and gage irregularities is analyzed based on the typical America track irregularities PSD. The bridge motion model is established by dynamic finite element method, In the thesis, the detailed process of mechanics matrices including mass matrices, stiffness matrices and the damp matrices of the spatial beam element is presented.In details, the main research work is as follows:1. Establishment of a more completed dynamic analysis model for vehicle and locomotives. The four-axle rolling stock with two stage suspension is used for the study and a space vibration analysis model constituting of such rigid bodies as carbody, bogie frame and wheelset is built. There are totally 31 degree of freedom, i.e, 5 for the carbody and the front and rear bogie respectively, that is horizontal movement, bounce, roll and yaw. The degree of freedom of the wheelset is 4 in total, including horizontal movement, bounce, roll, and yaw; Based on the Hamilton principle, the motion equations of the bridge was established by finite element method; the element mechanics matrices of spatial beam element with 12 degrees of freedom was also be educed.2. The detailed geometric relation of contact and the contact parameter with the contact states are given. Various of methods for solving the contact point are presented, that is analytic method aiming at the specific profile , the search in space method and trace method aiming at the arbitrary profile. In this paper, the program of iterative and the criterion of constringency is improved, so that it becomes more applicable. At the last section, the conclusion and the drawing of result is given.3. Base on the elasticity mechanic and the contact mechanic theory, the vertical contact force expressions is work out, long and short axes of contact ellipse spot is also given. Then the creep force formula was built according to the suppose that the creep force is considered as linear relations under the small creep ratio conditions suggested by Kalker.4. According to the compatibility condition of the wheel/track contact, a large complex coupling system constituting of vehicle subsystem and bridge subsystem was built, and a lot of conclusion and result for vehicle and bridge dynamic response was obtained using numerical integration method to solve the coupling system of vehicle and bridge; For the track irregularity, the classification and the reason why to produce the irregularity was given in this paper. Then the ordinary PSD graph used by domestic and oversea was presented in order to get the curve of random irregularity of the track in time domain through the method of trigonometric series and periodogram separately. finally, the analog result was work out through programming. During the process of solving, several fast time integration methods to solve the differential equations of motion for such a high degrees of freedom system are employed.
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