With the tendency of the railway transportation into heavy haul, more frequent usage of rail tracks and increased axle load, the problem of surface damage and fatigue is dominant on rails. Rolling contact fatigue (RCF), which leads to crack formation in rail track heads, is becoming a growing concern in the transportation industry. It occurs on or very close to the rail head surface, and is a significant cause of rail failure. The detection of cracks in RAILS is a critical requirement in the Railway industry. Cracks, if undetected will lead to rail fractures and consequently may lead to catastrophic accidents. Thus with the development and operation of high speed trains, condition based maintenance and monitoring becomes an important approach for the improvement of reliability and safety of rail transportation. Eddy Current Thermography (ECT) is an emerging NDT method especially for conductive material like rails which combines the advantages of eddy current testing and IR Thermography. Due to electrical conductivity, thermal conductivity and high permeability of rails, ECT is very suitable for its damage detections. This technology describes an inspection methodology which utilizes scanning induction Thermography in which coil is excited by a high frequency alternating current and induced eddy current are generated in sample placed near the coil. The thermographic camera is arranged to capture data indicative of a thermal response resulting from the flow of electrical current through the copper coil which scans the rail track. A computer system is configured to process the data from the thermographic camera to generate an indication of a presence of a discontinuity in the rails.

Scanning Induction Thermography (SIT) combines both Eddy Current Technique (ECT) and Thermographic NonDestructive Techniques (TNDT) [1,2]. This NDT technique has been earlier demonstrated for metallic components for the detection of cracks, corrosion, etc. [3-9] Even though Carbon-Fiber Reinforced Plastics (CFRP) has a relatively less electrical conductivity compared to metals, it was observed that sufficient heat could be generated using induction heating that can be used for nondestructive evaluation using the Induction Thermography technique. Also, measurable temperatures could be achieved using relatively less currents, when compared to metals. In Scanning Induction Thermography (SIT) technique, the induction coil moves over the sample at optimal speeds and the temperature developed in the sample due to Joule heating effects is captured as a function of time and distance using an IR camera in the form of video images. A new algorithm is also presented for the analysis of the video images for improved analysis of the data obtained. Several CFRP components were evaluated for detection of impact damage, location of stiffeners and disbonds using the SIT technique.

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