Damage tolerance of fractured rails on continuous welded rail track for high-speed railways
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Damage tolerance of fractured rails on continuous welded rail track for high-speed railways Yuan Gao1,2 • Ping Wang1,2 • Kai Wang1,2 • Jingmang Xu1,2 • Zhiguo Dong1,2
Received: 6 August 2020 / Revised: 1 November 2020 / Accepted: 4 November 2020 Ó The Author(s) 2020
Abstract Broken gap is an extremely dangerous state in the service of high-speed rails, and the violent wheel–rail impact forces will be intensified when a vehicle passes the gap at high speeds, which may cause a secondary fracture to rail and threaten the running safety of the vehicle. To recognize the damage tolerance of rail fracture length, the implicit–explicit sequential approach is adopted to simulate the wheel–rail high-frequency impact, which considers the factors such as the coupling effect between frictional contact and structural vibration, nonlinear material and real geometric profile. The results demonstrate that the plastic deformation and stress are distributed in crescent shape during the impact at the back rail end, increasing with the rail fracture length. The axle box acceleration in the frequency domain displays two characteristic modes with frequencies around 1,637 and 404 Hz. The limit of the rail fracture length is 60 mm for high-speed railway at a speed of 250 km/h. Keywords Rail broken gap Explicit FE method Damage High-frequency impact Stress mechanism
& Jingmang Xu [email protected] 1
MOE Key Laboratory of High-Speed Railway Engineering, Southwest Jiaotong University, Chengdu 610031, China
2
School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China
1 Introduction As an infrastructure for vehicles running on high-speed rails, track is a critical component that directly bears the multi-field coupling effect of vehicle and temperature load. During the long-term service of rails, under the effect of cyclic dynamic wheel load, construction deficiency and temperature effect, the rails are subject to various damages (see Fig. 1). In the section of seamless rails, the changes in temperature can cause enormous temperature force inside rails, thereby causing them to break eventually. To name a few, the rail of the upper line at K489 ? 140 m on Hengyang–Liuzhou railway was broken, the rail of the upper line at K2322 ? 490 m on Guangzhou–Shenzhen–Hong Kong high-speed railway was broken vertically, and the base metal of the rail of the upper line at K359 ? 790 m on Qingdao-Jinan railway line was broken (see Fig. 1). It has been admitted that the rail fracture is an unpredictable and extremely dangerous damage that seriously threatens the running safety of vehicles (Fig. 2). The rail fracture has a great significant influence on wheel–rail interaction and running safety of vehicles. In terms of geometric properties, after rails are broken the geometry and continuity of tracks are destroyed, which is mainly represented by three factors: broken gap, step and bending angle. Moreover in terms of mechanical properties, the geometrical discontinuity of rails caused by the broken gap results in the loss of
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