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.
Finite element analysis of the mechanical behaviour of insulated rail joints due to impact loadings
2016-03-01
15 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Finite element analysis of the mechanical behaviour of insulated rail joints due to impact loadings
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