Visualizing Ultrasound Propagation Using a Pulsed Laser and Its Application to Non-Destructive Evaluation of Impact Damage in CFRP Composite Laminates

This study demonstrates the ultrasonic technique that visualizes the wave propagation with the use of a pulsed laser for a nondestructive testing of CFRP composite laminates. In order to verify the technique, we visualized the Lamb-wave propagation in an intact CFRP cross-ply laminate. The S0 mode and the A0 mode were identified in the snapshots of the wave propagation through the calculated dispersion curves. Furthermore, we applied the technique to the damage detection in the CFRP laminate subjected to the impact loading. Although the impact damage was barely visible, the wave scattering due to the delamination was clearly observed in the snapshots as well as the S0 and A0 Lamb-modes. We also addressed the quantitative evaluation of the delamination using the B-scope image and concluded that the reliable detection and evaluation of the impact-induced delamination by the proposed technique are applicable to inspections of composite laminates.