Numerical and experimental investigation on debonding detection in honeycomb sandwich using air-coupled local defect resonance and coda wave analysis.

Non-contact ultrasonic testing of debonding in honeycomb sandwich structure has been a major challenge in industry. In this study, the air-coupled local defect resonance (LDR) technique with coda wave analysis is proposed for nondestructive testing (NDT) of debonding in honeycomb sandwich structure. Numerical simulations have been conducted to visualize the LDR behavior of debonding in honeycomb sandwich structure by air-coupled excitations, and a decorrelation analysis method is proposed for determining the interval of coda wave from received signals.

An Ultrasonic Reverse Time Migration Imaging Method Based on Higher-Order Singular Value Decomposition.

An ultrasonic reverse time migration imaging method, based on high-order singular value decomposition, is proposed in the study to solve the problems of low signal-to-noise ratio (SNR) and excessive artifacts in defect ultrasonic detection imaging results of materials with high noise levels. In this method, based on the 3D structural properties of the ultrasonic full-matrix capture data, higher-order singular value decomposition is directly performed with the 3D data. The method overcomes the difficulty in selecting the number of singular values in the original singular value decomposition noise-reduction algorithm and realizes the one-step noise reduction processing of all the signals.