Damage Detection On Composite Structures With A Single Frequency Excitation And Directional Wavenumber Spectroscopy

This work presents an improved damage-detection technique for nonisotropic composite structures using steady-state excitation-based laser Doppler vibration (LDV). Using a single fixed-frequency excitation from a mounted piezoelectric transducer, the full steady-state wavefield can be obtained using an LDV with a mirror-tilting device. After high-speed scanning, wavenumber filtering is applied to determine the dominant wavenumber components of the measured wavefield, which can be used for damage-sensitive features. In this process, the directional correction of the wavenumber is performed to minimize the anisotropic characteristic in damage detection using local wavenumber estimation. To validate this technique, several experiments were performed on nonisotropic composite structures containing delamination. The results showed that the proposed technique is very efficient in detecting and quantifying delamination and debonding damage on nonisotropic structures at high speeds.