Inspection of Sub-surface Defects Using Linear Frequency Modulated Thermal Wave Imaging

InfraRed Thermography (IRT) is an effective tool for Non-Destructive Testing and Evaluation (NDT&E) of structural components consisting of fiber reinforced polymers (FRP). Active thermography is a safe and reliable technique for health monitoring of these materials during in-service applications. The present work focuses on the defect depth resolvability in a carbon fiber reinforced polymer (CFRP) sample using frequency modulated thermal wave imaging (FMTWI) technique. The performance of the FMTWI has been explored using correlation-based pulse compression approach and compared with the conventional data processing approaches. Results shows the high sensitivity and resolution to resolve deeper defects of varying depths and diameters in CFRP sample using correlation approach.