Line Scanning Thermography for Rail Base Defect Detection

Rail base defects present significant maintenance challenges within the railway industry, as they are difficult to detect before they lead to failure. While various in-motion nondestructive evaluation (NDE) methods exist for inspecting rail, none of the existing NDE methods can inspect the rail base area reliably and efficiently. This paper presents finite element analysis (FEA) and experimental results applying a line scanning thermography (LST) approach developed for rail base area inspection. This work demonstrates the LST approach for dynamic inspection of thick steel components containing surface and subsurface anomalies. Initially, FEA was used to help design the experimental setup, then to compare trends in surface temperature variations with those from experimental trials. Through motorized testing, test specimens were moved through a region heated by three stationary line heaters, utilizing LST to capture temperature variations on the surface of each sample. The results have shown that subsurface features 6.3 mm in diameter and with aspect ratios greater than 1.5 were detectable in all specimens. This is a promising development that warrants further study.