A neutron diffraction investigation of residual stresses in rail ends after severe deformation of rail surfaces
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Date
2013-09-10
Journal Title
Journal ISSN
Volume Title
Publisher
Australian Nuclear Science and Technology Organisation
Abstract
Insulated rail ioints (lRJs) are an integral part of the rail track signalling system lRJs in heavy haul corridors around the iivorld are periodically serviced or replaced due to accumulated damage at the joint, rails are supported by tvvo fishplates which are fastened by bolts and nuts and, with the support of sleepers and track ballast form an integrated assembly. lRJ failure due to track fracture can result from progressive defects, the propagation of vvhich is influenced by residual stresses in the rail, which occur in the as-supplied track and then change significantly changes due to wheel rolling contact stress. lRJ failures can also occur well before the initiation of cracks or surface voids, when metal flow over the insulated rail gap (typically 6-8 mm Width) breaks the electrically isolated section of track and results in malfunction ofthe track signalling system.
ln this investigation, residual stress measurements vi/ere obtained from two rail-ends which had undergone controlled amounts of surface plastic deformation using a full scale wheel-on-track simulation test rig. Results were compared vvith those obtained from similar investigations
performed on rail ends associated vvith ex-service lRJs. Residual stresses vvere measured by neutron diffraction at the Australian Nuclear Science and technology Organisation (ANSTO). Measurements with constant gauge volume 3x3x3 mm3 vvere carried in the central vertical plane on 5mm thick sliced rail samples cut by Electric Discharge machine (EDM). Stress evolution at the rail ends was found to exhibit characteristics similar to those of the ex-service rails, with a compressive zone of 5mm deep that is counterbalanced by a tension zone beneath, extending to a depth of around 15mm. However, in contrast to the ex-service rails, the type of stress distribution in the test-rig deformed samples was apparently different due to the localization of load under the particular test conditions. ln the latter, there vvas no obvious evolution of d0 due to less accumulation of service load.
Description
Physical copy held by ANSTO Library at DDC: 620.1123/20
Keywords
Neutron diffraction, Residual stresses, Railways, Joints, Nuts, Fractures, ANSTO, Measuring instruments
Citation
Rathod, C., D., Luzin, V., & Wexler, D. (2013). A neutron diffraction investigation of residual stresses in rail ends after severe deformation of rail surfaces. Poster presentation to MECA SENS 2013 : 7th International Conference on Mechanical Stress Evaluation by Neutron and Synchrotron Radiation, 10-12 September 2013, Coogee, Menai, New South Wales, Australia, (pp. 159).