[7B1] Non-destructive evaluation of debonding in composites using air-coupled coda wave analysis and local defect resonance techniques
Z Li and J Jiao
Beijing University of Technology, China
An air-coupled local defect resonance (LDR) technique with coda wave analysis is proposed for the non-destructive evaluation of debonding in composites. A sensor consisting of 19 elements was used to simultaneously excite and receive ultrasonic waves. Air-coupled LDR experiments were conducted on two types of composite structure. It was found that the sensor lift-off and the selection of analysed signals have a significant effect on the detection capability of the LDR technique. For composites, the optimal sensor lift-off was found to be between 3.5λ and 5.5λ, where λ is the wavelength. Compared to multiple reflection echoes, the coda wave is more suitable for identifying the LDR frequency of debonding in composites. Air-coupled LDR experiments were conducted on composites with different debonding. The results show that the proposed non-contact ultrasonic technique effectively reduces the required incident acoustic energy and significantly improves the sensitivity and efficiency of debonding detection in composites.
Keywords: Non-destructive evaluation, air-coupled, coda wave interferometry, local defect resonance.
Keywords: Non-destructive evaluation, air-coupled, coda wave interferometry, local defect resonance.
