Visualization of Structural Defects Based on Ultrasonic Wave Propagation Imaging Technique Using Pulsed Laser System

Abstract

In this study, structural defects are visualized and localized based on a noncontact nondestructive testing (NDT) method which utilizes an ND: YAG pulsed laser system. The ND: YAG pulsed laser is used to generate Lamb waves of a plate-like structure and to scan specific area of the target structure for the visualization of the structure. Wave responses are measured using only single piezoelectric sensor. The measured responses are analyzed using 3 dimensional Fourier transform. The damage-sensitive features are extracted by wave-number filtering based on the 3D FT. Then, flaw imaging technique of a plate-like structure is conducted using the damage-sensitive features. Finally, the plate with a notch is investigated to verify the effectiveness and the robustness of the proposed NDT approach.