On the critical Speed of High-speed Railway Vehicles | Hans True
| | Abstract | All railway vehicles possess the characteristic that they start to oscillate without any external action when the speed of the vehicle exceeds a certain limit. This speed limit is called the critical speed of the vehicle. In this article we first describe this phenomenon of self-oscillation and show how the self-oscillation presents itself in test rides on railway lines. It is found under the continuous influence of the geometrical track disturbances and is distinguished as a sudden rise in the amplitude of the response of the vehicle to the track irregularities when the critical speed is exceeded. The amplitude of the self-oscillations reduces the comfort level appreciably and may even endanger the safe ride of the vehicle.
Second, the phenomenon will be explained as a result of the inherent nonlinear properties of the dynamic system of railway vehicles. Fundamental concepts from nonlinear dynamics will be introduced, and it is shown that these concepts suffice to explain the occurrence of the self-oscillations and the jump to high amplitude oscillations when the critical speed is exceeded.
Third, we shall demonstrate that theoretical methods from the analysis of nonlinear dynamic systems can be applied to calculate a lower bound for the critical speed of railway vehicles. The concepts also show how the critical speed must be measured in road tests. Then comparisons between the calculated critical speeds and measured critical speeds from road tests on railway lines used in daily operation show very good agreement.
Fourth, we shall briefly describe factors that influence the value of the critical speed. Both simpler and more complicated features will be illustrated. The influence of the alignment of curved track and resonance phenomena such as deterministic periodic variations in the track geometry and car design resonances will be discussed.
In the last section different methods for calculation of the critical speed will be presented. The methods include the recommendations by UIC. The section will end with a comparison of the methods, a recommendation and a conclusion | | Type | Conference paper [Without referee] | | Conference | Workshop: Noise and Vibration on High-Speed Railways, 2. and 3.October 2008, FEUP Porto, Portugal | | Year | 2008 Month October pp. 149-166 | | Publisher | Civil Engineering Department, Faculty of Engineering of the University of Porto | | BibTeX data | [bibtex] | | IMM Group(s) | Mathematical Physics |
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