Abstract
Rail foot flaws have the potential to cause broken rails that can lead to derailment. This is not only an extremely costly issue for a rail operator in terms of damage to rolling stock, but has significant flow-on effects for network downtime and a safe working environment. In Australia, heavy haul operators run up to 42.5 t axle loads with trains in excess of 200 wagons and these long trains produce very large cyclic rail stresses. The early detection of foot flaws before a broken rail occurs is of high importance and there are currently no proven techniques for detecting rail foot flaws on trains at normal running speeds. This paper shall focus on the potential use of thermography as a detection technique and begin investigating the components of heat transfer in the rail to determine the viability of thermography for detecting rail foot flaws. The paper commences with an introduction to the sources of heat generation in the rail and modelling approaches for the effects of bending, natural environmental factors and transverse defects. It concludes with two theoretical case studies on heat generated due to these sources and discusses how they may inform the development of a practical thermography detection methodology.
Highlights
The heavy haul rail sector in Australia hauls approximately one billion tonnes of bulk product every year with the majority of that being iron ore
This paper shall focus on the potential use of thermography as a detection technique and begin investigating the components of heat transfer in the rail to determine the viability of thermography for detecting rail foot flaws
Rail foot flaws have been cited by heavy haul rail operators in Australia as a risk to their safe and efficient operation
Summary
The heavy haul rail sector in Australia hauls approximately one billion tonnes of bulk product every year with the majority of that being iron ore. Transverse defects initiate at the edge of the foot caused by a nick or blow due to improper handling or usage of the rail This type of flaw continues to grow transversely and, if left undetected, will result in a broken rail as shown in. Does bending due to rolling stock passage generate significant heat flux in the rail for use as an IRT active excitation technique, and further, does the change in flexural rigidity caused by a defect significantly impact the heat flux due to bending. There is currently very limited research work in the area of rail heating due to rolling stock passage and thermography techniques for detecting rail foot flaws. The paper goes on to establish initial models integrating environmental effects such as convection and radiation and whether the change in flexural rigidity of the beam due to a flaw generates further heat due to bending
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