Mechanism of rail corrugation combined with friction self-excited vibration and wheel-track resonance

Abstract

In the present study on rail corrugation, a field investigation is carried out on a typical section of a Steel-spring Floating Slab Track (SFST) in the Beijing subway for studying the two distinct types of corrugations generated by the left and right rails in the curved sections of the metro line. Further, study is also done on the vibration response of track components when trains pass over the rail corrugations at a typical SFST curve having small radius of curvature (R = 300 m). The study establishes an SFST rail corrugation analysis model by effectively combining SIMPACK and ABAQUS. The proposed model considers the effects of both, friction self-excited vibration and resonance of the wheel-track system, for analyzing the reasons leading to inconsistent corrugation generated by the left and right rails in the small radius curve section of SFST. The results show that when the train load acts on the middle position of the adjacent steel-spring, it causes the rail to produce vertical bending resonance with the floating slab relative to the baseplate. This, in turn will result in increased corrugation which could reach 200 mm wavelength. At similar frequency, the anti-phase resonance of the unsprung mass and the track vibration mass, directly results in the formation of 200 mm corrugation. The wheelset-SFST system occurs near 68.4 Hz due to vertical torsional resonance of the floating slab. This leads to the rapid development of 200 mm corrugation in the curve's inner rail. When the train passes through the small radius curve section of SFST, the creep force between the guiding wheelset's outer wheel and the outer rail of the curve tends to saturate. This results in generation of 31.5 mm corrugation by the outer rail due to friction self-excited vibration. It is recommended to maintain the vertical stiffness of the fastener system above 50 MN/m to either stop or reduce the generation and development of corrugation at 200 mm and 31.5 mm wavelengths.