Nondestructive detection of delamination in carbon-fiber-rein forced plastics using superconducting quantum interference device

The use of carbon-fiber-reinforced plastic (CFRP) in aircraft and space str uctures is recently increasing. We investigated the possibility of nondestr uctively detecting a delamination in CFRP using a low-T-c first-order gradi ometric superconducting quantum interference device (SQUID) loop. A CFRP pl ate including a thin insulator sheet between the central layers was prepare d. The injected current method was adopted. The magnetic field due to the s heet was measured by a SQUID nondestructive evaluation system using the loc k-in detection technique. The position and size of the sheet were successfu lly detected by mapping the measured Held. The result agreed with that by u ltrasonic testing. Future application of this method for detecting deep-lyi ng flaws was discussed.