| Rail corrugation is a difficult problem in the railway industry for one century. It not only reduces the service life of vehicles and tracks, but also creates vibrations and noise which affect the passengers’ comfort. In an extreme case, the severe rail corrugation can even lead to derailment accidents. The research work on rail corrugation involves many subjects and fields such as material science, dynamics, rolling contact theory and tribology. There is still not any effective solution so far. The slight corrugation can be eliminated by grinding, but it will recur in a short time after grinding. For the severe corrugation, the rail must be replaced by new ones. Grinding or replacing the rails all costs a lot of money. Therefore, it is of important theoretical and economic significances to investigate into the rail corrugation.Professor Chen et al. put forward a viewpoint that the friction-coupled self-excited vibration between the wheel and rail can lead to rail corrugation. They thought that when a vehicle negotiates a sharp curved track, the creep force between the leading wheelset of the bogie and rail becomes saturated, which is equal to the normal contact force times the friction coefficient. And the saturated creep force can lead to self-excited vibration of the wheelset-track system which can cause rail corrugation. Based on this viewpoint, an investigation into rail corrugation in the transitional section of different track support structures on a sharp curved track is undertaken by using both complex eigenvalue analysis and transient dynamic analysis. The main research work includes:(1) Make a review on rail corrugation studies, and its generation mechanisms can be grouped into two major categories:it is assumed that there is an initial roughness on the rail surface and when the vehicle negotiates the rail repeatedly, the transient dynamic interaction between the wheels and rail leads to friction fluctuating, which can cause rail corrugation. The negative slope of creep force-creepage curve under the full sliding leads to stick-slip vibration of the wheelset-track system, which causes rail corrugation. Finally take an investigation into the effect of the track support structures on rail corrugation. It is found that the stiffness of rail pads and distance of sleepers also have obvious influences on corrugation.(2) Complex eigenvalue analysis by AB AQUS is applied to study the rail corrugation in a transitional section from a Cologne-egg support fastening track to a fix-dual short sleeper support track. The author established five finite element models and made several simulations of these models using the complex eigenvalue method and transient dynamics analysis. The result shows that the dominant frequencies of self-excited vibration of the wheelset-track system are about 290 Hz and 500 Hz in the fix-dual short sleeper support section and rail corrugations with two wavelengths are created. In the Cologne-egg fastening support section, the dominant frequency is about 500 Hz then only one corrugation with a wavelength is created. It can also be found that when the track is supported by only fix-dual short sleeper or Cologne-egg fastening the dominant frequency of unstable vibration of the wheelset-track system is all about 500 Hz, and corresponding corrugation wavelength is about 40～50 mm.(3) The transient dynamic analysis is applied to obtain the dynamic behaviors when the vehicle negotiates from the Cologne-egg fastening support section to the fix-dual short sleeper support section. And the power spectrum density (PSD) analysis is used to achieve the dominant frequency. The result shows that the self-excited vibration only occurs on the inner wheel and the corresponding low rail, the dominant frequencies are about 325 Hz and 480 Hz. In addition, it is found that the vibration occurring in the Cologne-egg fastening support section is severer than that in the fix-dual short sleeper support section. |
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