Non-contact Guided wave Tomographic Imaging in Plate by Laser-based Ultrasonic Techniques

摘要

Guided wave can propagate inaccessible area which cannot be inspected by conventional Ultrasonic Testing method. Contact-guided wave tests are impractical for investigating specimens with hard to access and rough surfaces or geometrically complicated features. A non-contact setup with a laser ultrasonic transmitter and receiver is quite attractive for guided wave inspection. The present work was done to develop a non-contact guided-wave tomography technique by laser ultrasonic technique in a plate-like structure. A method for Lamb wave generation and detection in an aluminum plate with a pulse laser ultrasonic transmitter and a Michelson interferometer receiver has been developed. In the images obtained by laser scanning, the defect shape and area showed good agreement with the actual defect. The proposed approach can be used as a non-contact-based online inspection and monitoring technique.