Numerical investigation of the fatigue performance of elastic rail clips considering rail corrugation and dynamic axle load

Abstract

To analyze the reasons for rail clip fracture, the characteristics of rail corrugation were first measured using a rail corrugation meter. The vibration acceleration of the fastener clips at the sections with/without rail corrugation was measured, and the effects of rail corrugation on the clip vibration were analyzed. After this, a vehicle--track coupling dynamic model and a refined model for the fastener system were established in order to study the effects of rail corrugation on the vibration acceleration and stress on critical points. Finally, the rail grinding limits were determined based on the fatigue analysis method and the damage accumulation theory from the aspect of the fatigue life of the clip. The results of the study showed that the main wavelength of rail corrugation at the rail clip fracture section was approximately 40 mm. The vibration acceleration of the clip caused by rail corrugation was too large. Under normal installation conditions, the maximum clip stress was 1490 MPa at the small circular arc on the rear arch, which was identical to the on-site fracture location. The intrinsic frequency of the clip was approximately 810 Hz. Rail corrugation excited and triggered the forced vibration of the clip, and induced resonance at a speed of 120 km/h and a wavelength of 40 mm. The large cyclic stress amplitude of the clip with rail corrugation increased from 44 MPa to 68 MPa when compared with the clip without rail corrugation. Rail clip fracture was caused by the naturally occurring resonance fatigue arising from rail corrugation. For metro lines designed with a maximum speed of 120 km/h, it was suggested to control the rail corrugation amplitudes with a wavelength of 40 mm, 50 mm, 30 mm, 120 mm and 160 mm to below 0.04, 0.08, 0.16, 0.19 and 0.2 mm, respectively, taking into account the fatigue life of the clip.

Effect of polygon-shaped wheels on fatigue fracture of fastener clips in high-speed railway lines

“…It should be noted that the pass frequency of the 24th-order polygonal wheel at a speed of 237 km/h is close to the first-order modal frequency of the clip. Since previous studies have confirmed that resonance occurs and accelerates the clip failure when the vibration frequency excited by the wheel-rail irregularity is close to the modal frequency of the clip, 12,14,24 the effect of the resonance phenomenon on the clip failure is not discussed in this paper. In addition, comparing the clip vibration in Figure 8 with the axle box vibration in Figure 3(b), there is a significant difference for acceleration PSD.…”

“…On these lines, some special phenomena are found: the railway wheels are often subjected to severe polygonal wear, 23 or the rails suffer from severe corrugation. 24 High-speed trains operate at a higher speed, and the wheel-rail interaction is more violent. The fastener failure in the high-speed lines will seriously threaten the operating safety of trains.…”

Development of a novel continuum damage mechanics‐based machine learning approach for vibration fatigue assessment of fastener clip subjected to high‐frequency vibration

“…Studies by Cui et al 2 and Hasap et al 3 have shown that under stable running conditions of railway trains, railway track components can operate, maintain, and be replaced according to design standards without premature damage. However, under typical wheel-rail coupling conditions such as rail corrugation, 4,5 uneven welding joints, 6,7 or wheel polygonal wear, 8 additional high-frequency excitation responses occur on the rail, leading to premature damage and failure of track components, particularly the clips. High-frequency vibration fatigue differs from conventional fatigue as it is closely associated with factors such as the frequency of load variations, structural resonance modes, and structural damping.…”

Design and parameters influence analysis of dynamic vibration absorber for fastener clips in high-speed railway

“…Through the wheel-rail coupling dynamics method, Ling et al (2014) verified that the static preload of clips and the cyclic wheel rail forces accelerated the fatigue damage of clips. According to the finite element method (FEM) result, Xiao et al (2017) and Wang et al (2021b) believed that the main reason for the fracture of e-shaped clips was the natural resonance fatigue caused by the rail corrugation. Hasap et al (2018) found that the life of the clips under abnormal impact load is greatly reduced, and the fracture position is consistent with the stress concentration position.…”