Structural damage detection on non-isotropic composite plates with steady-state acoustic wavenumber variations

Abstract

Recently, laser scanning-based full-field ultrasonic imaging techniques have emerged and gained tremendous interest from the structural health monitoring and non-destructive evaluation community. They offer several advantages, including noncontact structural measurement of structural response with high spatial resolution. This work presents an improved damage detection technique for non-isotropic composite structures using a steady-state response based on the use of a laser Doppler vibrometer (LDV). The basic principle behind this technique is to apply high-frequency steady-state excitations through a surface-bonded piezoelectric transducer and measure the subsequent steady-state wavefield using an LDV with a mirror-titling device. A wavenumber filtering process is then applied to determine the variations of the wavenumber components of each measured point. This technique performs directional correction of the wavenumber to minimize the anisotropic characteristic of composite plates for damage detection using local wavenumber variations. To validate this proposed technique, several experiments were performed on composite structures with introduced delamination damage. The results showed that the proposed technique is efficient in detecting and quantifying delamination and debonding damage on anisotropic composite structures.