Analysis of Causes for Rail Corrugation on Steel Spring Floating Slab Tracks of Metro Small Radius Curves

In order to explore the causes of corrugation on the steel spring floating slab track with the small radius curves of metro, the formation processes of rail corrugation were explained from the perspective of wheel-rail stick-slip vibrations. Firstly, according to the basic situation of the line, a three-dimensional finite element model of wheelset-floating slab track was established. Then, the wheel-rail contact stick-slip features and rail longitudinal wear characteristics were analyzed using the above model to quantify the occurrence trend of corrugation. Finally, the relationship between the natural vibration properties of wheel-rail system and the formation of corrugation was studied based on the complex modal theory. The results show that the stick-slip distribution of the inside wheel-rail interface changes periodically during the operation of the wheelset, indicating that the inside wheel-rail system has experienced periodic stick-slip vibrations, which may lead to periodic wavy wear on the inner rails, and finally form rail corrugation; the stick-slip distribution of the outside wheel-rail interface has not changed significantly in general, which indicates that there is no stick-slip vibrations in the outside wheel-rail systems, so it is not easy to form rail corrugation. In the longitudinal direction of the rail, the slip of the inner rail is significantly greater than that of the outer rail, illustrating that the longitudinal wear of the inner rail is greater; in the transverse direction of the rail, there is little difference between the slip of inner and outer rails, illustrating that the transverse wear of inner and outer rails is similar. The distribution of longitudinal and transverse slip nephograms of inner and outer rails shows a certain degree of periodicity, especially the longitudinal slip nephogram of the inner rail, with a wavelength of 28 mm close to the measured corrugation wavelength of 25 mm, which is consistent with the periodic characteristics of the contact stick-slip state of the inside wheel-rail interface, and further shows that the inner rail is more prone to serious periodic wear, namely rail corrugation. Combining the analysis results of wheel-rail contact stick-slip and wear features and wheel-rail system vibration characteristics, it may be concluded that the inner rail corrugation on the floating slab track with the small radius curves of metro is caused by the stick-slip vibrations induced by the unstable vibration modes of wheel-rail system corresponding to 664.1 Hz and 665.8 Hz, and the unstable modes arc all presented as the bending vibrations of the inner wheel relative to the track. The sensitivity analysis of parameters indicates that properly increasing the vertical stiffnesses of the fastener and the steel spring may play a positive role in the control of corrugation. © 2023 China Mechanical Engineering Magazine Office. All rights reserved.