EDDY CURRENT THERMOGRAPHY FOR RAIL INSPECTION

Abstract

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.