Probability of defect detection in glass fibre reinforced polymers using pulse compression favourable frequency modulated thermal wave imaging

Abstract

Infrared Non-Destructive Evaluation (IRNDE) is an emerging approach among the Non-Destructive Testing (NDT) techniques to evaluate sub-surface defects, due to its non-contact, whole field, fast and quantitative defect detection abilities. Among various recently proposed aperiodic Thermal Non-destructive Testing and Evaluation (TNDT&E) methods, pulse compression favourable thermal wave imaging approaches gained significant importance due to their improved defect detection capability in terms of sensitivity and resolution. The present work attempts to explore the applicability of pulse-compression favourable Frequency Modulated Thermal Wave Imaging (FMTWI) approach for testing and evaluation of Glass Fibre Reinforced Polymer (GFRP) sample by considering the Peak to Side Lobe Ratio (PSLR) as a figure of merit. Results clearly depict that in pulse compression favourable FMTWI exhibits higher probability for detection of sub-surface defects of higher aspect ratio, with the subtraction of background temporal temperature distribution of the test sample in comparison with the presence of background.