時間・周波数領域超音波映像法による接着層の非破壊評価

抄録

This paper proposes the time-domain and frequency-domain ultrasonic imaging techniques for non-destructive evaluation of adhesive layers between two Al plates. Two 1 mm thick, 20 mm square Al plates were bonded together by an epoxy adhesive. Ultrasound was transmitted into the adhesive layer sample, and the echoes reflected from the back of the sample were recorded by scanning the focused ultrasonic transducer. From the acoustic image (time-domain), the bonding area of the adhesive layer was evaluated. By repeating the frequency analysis of the echoes, two frequency-domain images were obtained. One was the resonant frequency image, which gave two dimensional information of the thickness of the adhesive layer, and the other was the minimum amplitude ratio image, which gave two dimensional information on the density of the adhesive layer. The mass of the adhesive layer determined from the data of the time-domain (bonding area) and the frequency-domain (thickness, density) was in good agreement with that measured by an electronic balance showing the validity of the proposed ultrasonic imaging techniques.