On the low cycle fatigue failure of insulated rail joints (IRJs)

Mandal, Nirmal Kumar

doi:10.1016/j.engfailanal.2014.02.006

Cited by 26 publications

(8 citation statements)

References 24 publications

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“…There are five material properties listed in Table 1. Of them, the yield strength, σy of 780 MPa is as per AS 15 and the other four hardening material properties were obtained from the literature 2,19 ; Kα is the maximum change in size of the yield surface, b is the rate at which the size of the yield surface changes as plastic straining develops , c is the kinematic hardening modulus and γ is the rate at which the kinematic hardening modulus decreases with the increase of plastic deformation.…”

Section: Fea Modellingmentioning

confidence: 99%

Ratchetting damage of railhead material of gapped rail joints with reference to free rail end effects

Mandal

2016

Proceedings of the Institution of Mechanical Engineers, Part F:

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Free ends of insulated rail joints occur because gaps between the rails and endposts can be created due to pull-apart problems as the rails contract longitudinally in winter and by degradation of railhead material. Dynamic behaviour of gapped rail joints changes adversely compared to that of insulated rail joints. Thus, material degradation and damage of gapped rail joint components such as rail ends, joint bars, etc. are accelerated. Only limited literatures are available addressing the free end of rail effects at rail joints, targeting stress and pressure distributions in the vicinity of the rail joints. To understand clearly the material degradation and delamination process of gapped rail joints, a thorough analysis of failure of both insulated rail joints and gapped rail joints and subsequent damage of the railhead material is necessary to improve the service life of these joints. A new three-dimensional finite element analysis is carried out in this paper to assess damage to railhead material when gapped rail joints form. Both narrow (5 mm) and wide (10 mm) gaps are considered, using a peak vertical pressure load of 2500 MPa applied cyclically at one rail end, forming vertical impacts. Stress distributions and plastic deformations in the vicinity of gapped rail joints are quantified using finite element analysis data and compared with that of the insulated rail joints to show the effects of free rail ends. Residual stress and strain distributions indicate the damage to the railhead material. Equivalent plastic strain (PEEQ) quantifies the progressive damage to the railhead material at the rail ends. The free end of rail effects can be further illustrated by comparing PEEQ for insulated rail joints and gapped rail joints. The railhead material of 5 and 10 mm gapped rail joints is more sensitive to permanent deformation compared to that of the corresponding insulated rail joints. Therefore, free rail end joints pose an increased potential threat to rail operations in relation to crack initiation, damage and premature failure of railhead material.

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Section: Fea Modellingmentioning

confidence: 99%

Ratchetting damage of railhead material of gapped rail joints with reference to free rail end effects

Mandal

2016

Proceedings of the Institution of Mechanical Engineers, Part F:

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“…This type of element is widely used in wheel/rail contact modelling. 16–19 In the job module, the simulation was completed statically in order to obtain the degrees of freedom of the displacement at the nodes of the global model, these were then used to run a sub-model of the rail as discussed in the following section.…”

Section: Finite Element Analysis Modellingmentioning

confidence: 99%

Finite element analysis of the mechanical behaviour of insulated rail joints due to impact loadings

Mandal

2014

Proceedings of the Institution of Mechanical Engineers, Part F:

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Insulated rail joints (IRJs) are safety-critical components in the signalling system of rail corridors. They are subjected to dynamic loads generated by heavy rolling-stock/track- system interactions and degrade faster than the other components of the rail track. Degraded IRJs diminish the reliability of the signalling system, thus posing a serious threat to the safety of rail operations. Therefore, there is a pressing need to closely examine the failure mechanisms of the end posts made of insulated material and inserted into the discontinuity in the rail at IRJs with a view to improving their service life, reliability and efficiency. Only a limited literature is available that examines different materials for IRJ end posts, and these primarily focus on contact pressure and contact stress distributions in the vicinity of the end post, disregarding the damage to the rail ends and end post materials. In this paper, a detailed three-dimensional finite element analysis procedure is carried out to quantify plastic deformation and material damage to the end post and railhead materials of IRJs due to a wheel load above that of the shakedown limit of rail steel. A modified Hertzian contact pressure distribution is considered in this simulation. A 5 mm thickness of an end post is considered at the discontinuity in the rail, which is required to form the six-bolt IRJ. Three popular IRJ end post materials are considered in this study: fibreglass, polyhexamethylene adipamide, and polytetrafluoroethylene. A total of 2000 cycles of a 174 kN dynamic wheel load (in pressure format over the wheel/rail contact patch) are applied on the top of the rail’s surface in the vicinity of the IRJ. Equivalent plastic deformations along with vertical and longitudinal plastic strains for unloaded conditions are presented. The strain plots depict damage of end post materials and ratchetting failure of rail ends. The ratchetting failure modes follow the established trend of decay in ratchetting rate in successive wheel load cycles. Comparisons of strain and stress on the railhead surface and in the railhead sub-surface considering all three different end post materials are put forward. Out of the three end post materials, fibreglass is the optimal material considering the ratchetting mode for the damage of the railhead material.

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“…An et al [12] proposed a grid-based analysis model for the effects of casual factors on rail break risk based on the Cox's proportional hazards regression analysis method and compared the simulation results with the data of broken rails and casual factors, which can provide accurate understanding of the mechanism of rail break. Most research mainly concerns the effect of broken gap on the running safety of vehicles [13][14][15][16][17][18][19], whereas a few consider the wheel-rail contact behavior or even the secondary fracture caused by the wheel-rail impact if the rail fracture is not detected timely [20][21][22][23]. In addition, there is no experiment data of ballastless rail gap in China.…”

Section: Introductionmentioning

confidence: 99%

Damage tolerance of fractured rails on continuous welded rail track for high-speed railways

Gao

Wang

et al. 2020

Rail. Eng. Science

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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.

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On the low cycle fatigue failure of insulated rail joints (IRJs)

Cited by 26 publications

References 24 publications

Ratchetting damage of railhead material of gapped rail joints with reference to free rail end effects

Ratchetting damage of railhead material of gapped rail joints with reference to free rail end effects

Finite element analysis of the mechanical behaviour of insulated rail joints due to impact loadings

Damage tolerance of fractured rails on continuous welded rail track for high-speed railways

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