The wheel/rail interaction and response due to the parametric excitation by the varying dynamic stiffness of a discretely supported track have been studied using a spatially quasi-static method, based on the fact that the structural wave propagation speed in the rail is much greater than the train speed in the audible frequency range. The point receptances of a track at different positions in a sleeper bay are calculated. Then an equivalent time-varying model is developed for the track in accordance with the space-varying receptances. Using this track model combined with a mass wheel model, the wheel/rail interaction and response to the parametric excitation are simulated. The results are compared with those from a moving irregularity model and the differences between the moving wheel and moving irregularity models are examined from various aspects of wheel/rail dynamics. The wheel/rail interaction force due to the parametric excitation increases with the running speed of a train. Although the contact force spectra comprise many harmonics with a fundamental frequency at the sleeper-passing frequency, the components around the pinned-pinned resonance frequency also show a high level. This is because a discretely supported track displays the greatest differences in the receptance at the pinned-pinned resonance. It is therefore expected that the higher level of contact force generated around the pinned-pinned resonance may be responsible for short pitch corrugation and a wheel/rail interaction model excluding the parametric excitation might not be appropriate for the prediction of corrugation growth. For railway rolling noise predictions, using a moving irregularity model to calculate wheel/rail interaction could under-estimate the noise emission level to some extent, particularly at low frequencies, because the components due to the parametric excitation are omitted from such a model. On the other hand, for the wheel/rail impact simulations due to the wheel or rail discontinuities, use of a moving irregularity model will not cause significant errors as the impact components are greater than those due to the parametric excitation. Since the model used for the predictions is idealised and some effects present in practice are neglected, the results presented in this work should be seen as an upper bound.
On the parametric excitation of the wheel/track system
Zur parametrischen Anregung des Rad/Schiene-Systems
Journal of Sound and Vibration ; 278 , 4/5 ; 725-747
2004
23 Seiten, 16 Bilder, 28 Quellen
Article (Journal)
English
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