Three-dimensional Imaging of Subsurface Defect in CFRP using Photoacoustic Microscopy

Nakahata, Kazuyuki; Ehime University; Japan

Nakahata, K.; Ehime University; Japan
Ogi, K.; Ehime University; Japan
Namita, T.; Kyoto University; Japan
Ohira, K.; Japan Probe Co., Ltd; Japan
Maruyama, M.; RIKEN; Japan
Shiina, T.; Kyoto University; Japan

ID: ECNDT-0296-2018
Download: PDF
Session: Composite General 2
Room: G1
Date: 2018-06-11
Time: 15:20 - 15:40

Photoacoustic (PA) imaging utilizes an ultrasonic wave generated by optical excitations with a short-pulse laser. A pulsed laser illuminates the target zone, then a rapid thermo-elastic expansion generates broadband high-frequency ultrasonic waves. In this study, the accurate depth and size of subsurface defects in a carbon fiber reinforced plastic (CFRP) are evaluated using the PA microscope. In the PA imaging, the ultrasonic generation is affected by the optical property of the target material and the wave length of laser. The laser with 532 or1064 nm wavelength is irradiated from the top surface of the CFRP, and the ultrasonic wave is received by an immersion array transducer on the same side. Here, we prepare CFRP specimens with subsurface delaminations and inclusions between layers. The three-dimensional shape of the subsurface defects between the 1st and 2nd plies can be clearly reconstructed. By applying a light-absorption material on the surface, large amplitude of ultrasonic wave generates from the surface of the specimen, and consequently the S/N ratio of scattered wave from the defects can be dramatically improved.