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Experimental investigation into the use of thermography for the detection of rail foot flaws
conference contributionposted on 27.06.2018, 00:00 by Christopher BosomworthChristopher Bosomworth, Yan SunYan Sun, Maksym SpiryaginMaksym Spiryagin, Sanath AlahakoonSanath Alahakoon, Colin ColeColin Cole
The improvement in Rail Defect Management practices for the rail head has seen a decrease in incidents caused by this section of the rail. However, due to the lack of reliable detection techniques for the rail foot, incidents resulting from flaws in this region are continuing to occur. The foot of the rail is exposed to large tensile stresses as a wheel traverses the rail and, for the heavy haul network being studied, the axle loads are significant, reaching up to 40t. Any manufacturing irregularity, physical damage or environmental exposure in the foot when subjected to these tensile stresses may result in cracks forming that, if left unchecked, have the potential to result in a broken rail. Broken rails pose significant cost and safety issues for rail operators due to the increased derailment risk. This paper shall present an experimental investigation into the use of thermography for the detection of rail foot flaws. Thermography is a common Non-Destructive Testing (NDT) technique used for measuring the thermal radiation emitted by an object. The thermal radiation is converted to a temperature map and this map, or thermogram, can be studied to identify areas of unexpected temperature fluctuation that may be indicative of a fault. The investigation shall examine a number of different foot flaw types including under the foot, sub-surface cracks and visible cracks. The rail shall be exposed to environmental conditions similar to those of the Pilbara region in the northwest of Australia where ambient temperatures can reach 50°C and a thermography camera used to record the thermogram. Visual analysis of the thermogram will be presented demonstrating the capability of thermography to detect the generated crack types. The results of this experimental investigation shall inform further research by ACRI into foot flaw detection from a moving vehicle.