Non-contact characterization of debonding in lead-alloy steel bonding structure with laser ultrasound

This paper presents the non-contact characterization of debonding defects in lead-alloy steel bonding structure with ultrasonic waves generated and detected by lasers. Using the 3D finite element (FE) method, the thermoelastic excitation and propagation of ultrasonic waves are simulated. The effect of debonding defects on wave field distribution are clarified. Combining experiment method, the feature signal for characterizing the debonding defects are extracted, the appropriate wave frequency and probe position are obtained. The characterization of debonding defects in different sizes are analyzed, and the laser ultrasonic C-scan imaging of the specimen with simulated debonding defects is realized. The results prove that the noncontact characterization of debonding defects in lead-alloy steel bonding structure can be realized with laser ultrasound, and the circular debonding defects greater than 4 mm in diameter are characterized through C-scan method.