On evaluation of CFRP composite laminates using ultrasonic with polarization direction

This study has been intended for a precise evaluation of the polarity of ultrasonic transducer by a theoretical analysis of the phenomenon found in each internal plies of CFRP laminate when ultrasonic wave from the transducer passes through them. An ultrasonic experimental setup was made with 1 MHz ultrasonic transducer referring to the result of Dokun's experiment. Evaluation of A-scan images by ultrasonic transducer at angles of 0°, 30°, 90° and 150°, respectively, was made using CFRP quasi-isotropic laminate specimen. In addition, where a visual observation is difficult, C-scanning evaluation method was utilized for precise evaluation of polarity of the ultrasonic transducer. Further, based on the results of theoretical analysis, performed a simulation in the form of polar coordinates with increment of 1° from 0° to 360° of peak-to-peak amplitudes. With the transmitter fixed at 0° direction and the receiver changing the direction from 0° to 90°, the polarity of receiving transducer was evaluated by performing scan display three times at each angle. The results were compared with A-scan images. Through these processes, the reliability of experiment for evaluating the polarization direction of ultrasonic transducer could be upgraded.