Debonds and Water-Filled Defects Detection in Honeycomb Sandwich Composites Based on Pulse Infrared Thermography NDT Technique

Honeycomb sandwich composites (HSCs) have been extensively used in aerospace, automotive and shipbuilding industries due to their light weight, high temperature resistance, high strength and fatigue resistance. In this study, the infrared thermography was used to detect debonds and water-filled defects in HSCs specimens under pulsed thermal stimulation. To improve the efficiency of defects detection, dynamic thermal tomography (DTT), principal component analysis (PCA) and total harmonic distortion (THD) techniques were applied to the raw infrared image sequences. The results show that, in the inspection of HSCs, the defect identification results can be improved by using the image processing techniques mentioned above, while the signal-to-noise ratio (SNR) can be significantly improved by means of the THD technique. It is confirmed that debonds and water-filled defects in the HSCs can reliably be detected and identified by using the technique of pulse infrared thermography nondestructive testing.