Low-Power Fully Acoustic Non-Destructive Testing of Glass Fiber-Reinforced Composite Plate Utilizing Local Defect Resonance

Abstract

In this paper, a low power fully acoustic non-destructive testing (NDT) of glass fiber reinforced composite plate has been presented. Input acoustic power in microwatt range has been used for local defect resonance (LDR) based delamination activation. Both numerical and experimental results are compared here. Numerical simulation has been carried out in ABAQUS platform. An oblique incident wave interaction with 3D composite plate has been created and the sound radiation pattern over the plate has been studied with an air layer over the plate. In experiment, the sound has been generated by a piezo-speaker and a MEMS microphone has been used for reception over the plate. Moreover, a laser Doppler vibrometer has been used for LDR frequency and corresponding mode shape validation. Frequency spectrum, mode shape at LDR frequency, best wave impinging angle, efficiency and sound directivity patterns are studied. θ, ϕ = 10°, 30° has been found to the best direction for sonic excitation. Moreover, fully acoustic system is found to be more efficient than partial acoustic system, i.e., contacts excitation. This method can be used for inspection of large structures due to long distance non-contact excitation.