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One-Sided Nondestructive Evaluation of CFRP Composites By Using Ultrasonic Sound
Kwang-Hee Im(임광희),Gui-Lin Zhang(장계림),Sung-Rok Choi(최성록),Chang-Hee Ye(예창희),Je-Sung Ryu(류제성),Soo-Hwan Lim(임수환),Min-Gui Han(한민규),David K. Hsu 한국생산제조학회 2011 한국생산제조학회지 Vol.20 No.1
It is well known that stiffness of composites depends on layup sequence of CFRP(carbon fiber reinforced plastics) laminates because the layup of composite laminates influences their properties. Ultrasonic NDE of composite laminates is often based on the backwall echoes of the sample. A pair of such transducers was mounted in a holder in a nose-to-nose fashion to be used as a scanning probe on composites. Miniature potted angle beam transducers were used ( Rayleigh waves in steel) on solid laminates of composites. Experiments were performed to understand the behavior of the transducers and the nature of the waves generated in the composite (mode, wave speed, angle of refraction). C-scan images of flaws and impact damage were then produced by combining the pitch-catch probe with a portable manual scanner known as the Generic Scanner (”GenScan”). The pitch-catch signal was found to be more sensitive than normal incidence backwall echo of longitudinal wave to fiber orientation of the CFRP composites, including low level porosity, ply waviness, and cracks. Therefore, it is found that the experimentally Rayleigh wave variation of pitch-catch ultrasonic signal was consistent with numerical results and one-side ultrasonic measurement might be very useful to detect the defects.