Nondestructive analysis of rolling contact fatigue cracks using induced scanning thermography

Rolling contact fatigue (RCF) produced by wheel-rail interaction is now considered to be a critical factor that causes failure. Throughout this work, induced scanning thermography (IST) for detecting RCF defects at different depths is investigated. The original thermal sequences could not utilize the features at the heat dissipation stage; thus, a data reconstruction method, including principal component analysis (PCA) and Tucker factorization, was employed to extract the spatial and time patterns. In addition, detectability was evaluated across a range of speed studies. The Tucker-PCA combination algorithms obtained defects with improved quality, showing a clear boundary over the velocity range of 1-4km/h, which dramatically suppressed background noise. A unique gradient response characteristic in the cooling phase was summarized and utilized through experimental verification in order to recognize defect width.