アコースティック・エミッションの放射形式計測によるアングルプライCFRP積層板の微視割れモード評価

概要

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A new acoustic emission (AE) analysis method for fiber reinforced composite material was developed. Phase combinations of first arrival quasi-longitudinal wave of AE in plate (Lamb wave) was analyzed based on AE spherical radiation pattern in infinite homogeneous medium, plate wave propagation properties and detection properties of piezoelectric AE sensor. Angle ply carbon fiber/epoxy composites were prepared to the AE and Ultrasonic C-scope tests to evaluate the fracture processes of delamination. Three stages characterized both the compliance and the AE properties were observed during tensile tests. The spherical AE radiation pattern analysis could distinguish into three types of fracture mode for detected AE events, such as tensile fracture, shear fracture and mixture fracture of tensile and shear. By analyzing the AE spherical pattern events, C-scope, surface and fracture surface observation, fracture processes of the angle ply CFRP were proved. At stage I of which is linear load-strain region, debondings occurred at notch tip along the fiber orientation of each layer as shear fracture. At stage II of which is transient region between stage I and III, coalescence of the debonding in each layer occurred as tensile fracture. At stage III of which is heavy increase of the compliance and the AE counts region, the debonding and the coalescence occurred at the same time along the fiber orientation.