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.
Highlights
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
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
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
Summary
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. The test method held certain limitations: the velocity of the train was relatively low compared to the high-speed railway, and the wheel–rail contact stress could not be directly and accurately measured by instrument For this reason, aiming at the high-frequency wheel–rail impact at broken gap and its influence on running safety, many scholars have used the numerical simulation method for safety analysis. To recognize the secondary fracture of rail and determine the tolerance of rail fracture length, a threedimensional explicit finite element model of rail fracture is established to simulate the process where wheels impact the back rail at the broken gap, and the wheel–rail dynamic high-frequency impact and vehicle running safety as well as the stress mechanism of the rails at the broken gap are investigated; the possibility of secondary fracture to the back rail under the effect of high-frequency impact can be evaluated, which can provide a certain reference for the service and maintenance of steel rails. The frictional rolling contact solutions in contact patch can be validated by comparing the results from CONTACT and Hertz, as shown in Table 1, where the simulation results of the explicit finite element method are consistent with those obtained from CONTACT and Hertz
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