Suppressing localized-rail bending modal vibration by designing high-frequency vibration-absorbing fasteners

Since the view that the localized rail 3rd-order bending mode (B3 mode) can cause high-order polygonization (mainly 18~23) of high-speed train wheels was put forward in 2017, many scholars have attempted to link a connection between the localized rail bending modes and wheel polygonization phenomenon and polygonal wheel passing frequency (PWP frequency). Since most of the reported studies did not consider the multi-component assembly characteristics of the fastener system, the phenomenon of localized rail bending modes could not be accurately reproduced by many theoretical models, which hindered scholars from exploring the solution to the polygonal wheel problem. To advance the research on this scientific issue, this paper first establishes a flexible track model considering the structural and parametric characteristics of fasteners, verifies the model by using vehicle tracking test data, and then investigates the influence of fastener parameter matching on the localized rail bending modes, and obtains the following conclusions: (1) There is nearly 1:1 mapping relationship between the localized rail bending modal frequency and PWP frequency, which supports that the localized rail bending mode is one of the causes of wheel polygonization; (2) The iron plate of the fastener system plays a role of dynamic vibration absorber (DVA) in the vehicle-rail coupled system, and the quality of the iron plate and the stiffness of the upper/lower rubber pads significantly influence the localized rail bending modal frequency. Finally, this paper proposes a design principle of a high-frequency vibration-absorbing fastener, which provides a feasible solution to mitigate the localized rail bending modal vibration and high-order wheel polygonization. Meanwhile, it points out that this measure may induce other high-frequency vibration problems, e.g., aggravating modal vibration above 800 Hz. Further, this paper proposes a concept of differentiated arrangement of fasteners, suggesting that different high-frequency vibration-absorbing fasteners be installed in different sections of the whole line to make the localized rail bending modal frequency of the whole line disordered, thus disrupting and further mitigating the development of the wheel polygonization.