ＡＥによるチョップドストランド型ＣＦＲＰの破壊機構の解明

Abstract

In this paper, the acoustic emission method was used for clarifying the fracture mechanism of carbon fiber chopped strand reinforced plastics with a center crack through the thinkness in tensile deformation. It was observed that the load vs. displacement curve could be divied into five regions, and the fracture mechanism was made clear by combining the behaviour of acoustic signals in each region with SEM observation. The generation of initial stable cracks was clearly shown in the relationship between stress intensity factor and acoustic cumulative energy and that between stress intensity factor and acoustic cumulative events. The development of stable cracks was noticed by the change in acoustic event count rate. There existed two peaks in amplitude distribution. A three dimensional amplitude distribution was made, which gave the detailed relationship between the acoustic amplitude and the failure process. From this distribution, the acoustic event count rate can be classified into two types with low and high amplitude events which have different characteristics of microfracture mechanisms. Furthermore, a model was proposed to explain the pulled-out failure of chopped strand tapes.