Characterization of Rolling Contact Fatigue Cracks in Rails by Eddy Current Pulsed Thermography

Locating and characterizing rolling contact fatigue (RCF) cracks in rails is gaining attention in the railway industry. Eddy current pulsed thermography (ECPT) can detect such cracks by combining the benefits of electromagnetic excitation and thermal diffusion. To date, most studies focus on investigating specific features based on artificial defects, and verification on real cracks is lacking. In this article, to establish the best means of characterizing cracks of different inclination angles, eight spatial and temporal ECPT features are evaluated on idealized and real RCF cracks. Results show that longer time slots and pulse durations make the relations clearer. For the evaluation of real RCF cracks, the area-based and the kurtosis-based features are the most suitable and robust measures for characterizing inclination angles.