Vibration Of High Speed Train Overhead Wire Systems

The vast territory of China and the Chinese tradition of family reunion for celebrating New Year provide the space requirement for the large-area and long-time operation of high speed railway. In addition, in the progress of perusing a stable development of china economic, the urbanization policy favored by the government provides vast market demand for the high speed train. Furthermore, leaded by a series of concepts about technology adoption, digestion, absorption and innovation, and also by the national strategies of "the Belt and Road" and "Going Out", the High Speed Train (HST) has put into large-scale application. With the increasing of running speed of HST, the Pantograph and Catenary Interaction (PCI), which is one of the three basic mechanics-interaction relationships of HST, undergoes more complex circumstances and consequently put forward more demands of systematical investigation. As a result, in order to address the application requirements of designing and construction of overhead catenary system, and by using theoretical analysis, computational simulation and experimental test, this paper researches the dynamical behavior of overhead catenary system and the PCI, including the basic dynamical characteristics of catenary under moving load, the experimental researches for catenary vibration and its damping characteristics of catenary, the response behavior of catenary under a real pantograph together with the PCI, the response characteristics of catenary under double pantographs and the mechanism of variation of contact force between pantograph and catenary (PAC).First, regarding the basic dynamical characteristics of catenary under moving load,several key issues are discussed. In particular, an iterative Finite Element Method (FEM) is adopted for the catenary form finding, in which the maximum displacements of Contact Wire (CW) and Messenger Wire (MW) can be decreased to 0.202 mm and 0.024 mm,respectively, while the CW and MW tension discrepancies between the designing and real value can be decreased to 0.0045 % and 0.0625 %, respectively; The relationship between the elasticity spatial distribution and the wires' tension are analyzed too; By adopting the dispersion relation of elastic wave guide to distinguish the different characteristic of two models that usually used to model catenary wire, the group velocity and phase velocity of elastic wave propagated upon catenary are clarified. While for the group velocity, it is identified by using the catenary displacement response contour that spread on the time-space plane, and the precise of identified result is proved by the experimental result to be less than 2 %; By using the theoretical analysis, the wave propagate characteristic around the catenary positionner and dropper are studied; Finally, the resonance of catenary under excitation from the moving load are discussed, and the results show that, when the wave lengths of the excited elastic wave match the wave length of the catenary natural modes that have modal nodes at the positioner, the resonance occur.Second, for the experimental test of catenary vibration and the modal parameters identification, on one hand, based on the displacement response histories of a real catenary and an iterative FEM analysis, a combined approach used to identify the damping characteristic of catenary is proposed, in which the damping ratio and Rayleigh damping coefficients are identified simultaneously. The results show that, the catenary modal damping ratio at 1.19 Hz is approximately 1 %, and the mass and stiffness proportional Rayleigh damping coefficients are approximately 0.02845 and 0.00274, respectively; On the other hand, the beat phenomenon of catenary response is discussed, and the harmonic frequencies together with its source are studied too, in the mean time, the local variation pattern of catenary response that affected by the propagated elastic wave are analyzed by using the catenary displacement response contour that spread on the time-space plane.Concerning the response behavior of catenary under a real pantograph and the PCI, it is found that, when excited by a moving pantograph, the CW and MW of both the simple stitched and elasticity stitched catenary vibrate synchronously, in addition, the results also show that, in the low speed range, the displacement history or spatial deformation wave are symmetrical about the time or spatial position when the pantograph passing by, however,the symmetry is broken down in relative high speed range. Especially in the high speed range, the displacement history or spatial deformation wave of catenary have an obvious boundary between the disturbed and un-disturbed sections, and the stress level at the boundary has a large value because of the uplift effects from the moving pantograph, what's more, seen from the stress level, the risk point of catenary locate at the suspension of MW,when the moving speed of pantograph is 0.8 times the wave speed of catenary, the stress level of MW in simple stitched and elasticity stitched catenary have an incensement of 51.74 % and 47.1 %, respectively, for the CW in both kind of catenary, the stress increment is about 13.12 % and 10.96 %, respectively, while for the elastic dropper in the elasticity stitched catenary, the stress increment is about 16.40%. For the PCI, the variation pattern of current collecting quality is figured out by the spectrum analysis. Under different running speed, when the span passing frequency excess the first modal frequency of the catenary second mode group, the catenary vibration jump into second order, and the current collecting quality will benefit from this phenomenon. While at a specific running speed, by adjusting the catenary structural parameters, and making the dominant frequencies in the contact force being smaller than the dropper passing frequency, the current collecting performance will be increased. Finally, for the elasticity stitched catenary, the effects from the tension or length of stitched dropper on the PCI are analyzed, and the results show that,the tension or length have less influences on the contact force but change the catenary elastic distribution between the positioner and the second dropper, affecting the uplift displacement of the pantograph collector consequently.At last, for the response characteristics of catenary under double pantographs and the mechanism of variation of contact force between PAC, on one hand, it is found that, the vibration behavior under two pantograph excitation can be reconstruct from those catenary response under just one pantograph. On the other hand, the variation mechanism of contact force disturbed by the elastic wave is studied by theoretical analysis and is successfully applied in the two pantograph collecting currency case to interpret the periodically changing of the performance of the rear pantograph. In particular, when the elastic wave meets the moving pantograph and disturbs the contact state between the pantograph and wave guide, because that, in one circle of wave, different part that with different phase can counteract the wave effects by each other, the continuously propagated waves give out a steady disturbence pattern to the contact force. In the two pantograph case, both for the simple stitched and elasticity stitched catenary, the front pantograph performance have nothing to do with the rear one, however, the exited elastic wave by the front pantograph will affect the contact state of the rear one, and the effects will be advantage or disadvantage, depending on the spatial distance between the two pantographs and their running speed. At specific running speed, if the CW has a positive displacement at the contact point between the CW and the rear pantograph, the performance of the rear pantograph will be benefited, and the improvement level is positively correlated to the CW velocity at that contact point.