2925 一方向複合材料のクリープ寿命予測(S27-2 複合材料の動向とその加工技術(2),S27 複合材料の動向とその加工技術)

Abstract

Delayed fractures in carbon-fiber-reinforced polymer matrix composites can be observed even at room temperature due to an accumulation of micromechanical damages, such as time-dependent interfacial debondings or fiber breakage. In this study, the creep-rupture time in unidirectional composites consisting of carbon fiber reinforcement and vinylester resin is predicted under consideration of the progress of interfacial debonding which decreases rupture strain of the composites due to increase of the stress recovery length in time. The decrease of the rupture strain in unidirectional composites is formulated based on the global load sharing, which assumes that lost load distribution involved a fiber break is uniformly redistributed to all the intact residual fiber in the range of the stress recovery length. Time-dependency of the stress recovery length including the interfacial debonding length is analytically and experimentally investigated using carbon/vinylester single-fiber composite as a function of time and specimen strain. The creep rupture prediction is completed by means of putting the increase of stress recovery length into it. The validity of this creep rupture prediction is discussed by investigation of the residual strength after quasi-creep test, which must be derived by the formulated creep rupture prediction.