Air-Coupled Ultrasonic Inspection Method for CFRP

Carbon Fiber Reinforced Plastics (CFRP) helps to lighten components, because it has the advantage of high strength-to-weight ratio. Therefore, it has come to be utilized as parts of aerospace etc. The composite pressure vessel is one of the apparatus of CFRP coated with insulation on the inside. In this study, an investigation of the air-coupled ultrasonic technique, which could be done from one side of a vessel, was carried out in order to detect interface disbondings between CFRP and insulation by non-contacting from the external surface of a vessel. Moreover, focusing probes by means of a lens and phased array probe were manufactured to improve the detectability of the defects. As a result, it was confirmed that the internal defects could be detected by the non-contacting inspection from one side, and the detectability was improved by focusing ultrasonic beam. Furthermore, the display of the disbonding image using probe in which the elements were arranged circularly was investigated and the system for field application was also developed.