A novel reference-free technique for processing one-sided thermal NDT results in the time domain

Abstract

In this study, simple analytical and numerical solutions were used to introduce a novel technique of processing thermal nondestructive testing (TNDT) results using a one-sided test procedure to determine material apparent diffusivity and represent TNDT results in the time domain without identifying non-defect areas. The technique is based on establishing dimensionless levels in the temperature decay functions that describe the cooling profile of a test sample after pulsed heating. The times when such levels cross the front-surface response curves may serve as specific heat transit times and may reduce the temperature-related noise. The corresponding level images are not associated with any reference point and allow determining apparent diffusivity thus providing more contrast representation of defect indications than raw infrared images.