ガラス繊維強化ポリカーボネートのアコースティックエミッションと繊維含有率との関係

Abstract

The signals of acoustic emission (AE) which are emitted in the vicinity of notch were detected during the fracture process on the test specimens of glass fiber reinforced polycarbonate (FRPC) in which the fiber weight contents were changed. The AE cumulative event, the AE cumulative energy and the distribution of AE amplitude were discussed with relation to the fractography in order to study the fracture mechanism of these specimens.It was found that the AE signals of these specimens were the burst emission type, and the AE events increased with an increase in displacement and also in fiber content. The relationship between the AE cumulative event or the AE cumulative energy and the stress intensity factor could be represented by the folded line in log-log representation. It is considered that the folded point represents the initiation point of stable crack in the specimen. The fracture pattern for the specimen of lower fiber content differed from that patterns for the specimen of high fiber content. It seems that this difference is reflected in the distribution of AE amplitude. The AE amplitude for the specimen of low fiber content was sharply distributed in a narrow range, while that for the specimen of high fiber content was widely distributed in a wide range. When the emission source of AE is estimated from the observation of fractured surfaces, it is considered that the low AE amplitude represents the debonding between fiber and resin as well as the pulling-out of fiber, while the high one represents the friction between fibers and the rupture of fiber.