J043023 繊維不連続部を有するCFRP積層板の損傷挙動([J04302]高分子基複合材料の加工と評価(2))

Abstract

In fabricating complicated laminated composite structure by using prepregs, there may be fiber discontinuity in the structure which may influence the mechanical response of the structure. The fiber discontinuity also may act as a source of stress concentration and damage. In this regard, it is very important to understand the effect of fiber discontinuity. In the present study, the effect of fiber discontinuity in CFRP laminate is investigated experimentally. The damage initiation and growth near the fiber discontinuity are also discussed. Laminates which contain fiber discontinuity with different thicknesses are prepared. Tensile tests were conducted to investigate the mechanical response of the laminates. We observed the edge surface of the specimen around the fiber discontinuity. The strain away from fiber discontinuity show almost linear stress-strain relation until a certain stress level. The strain increases rapidly at a stress point, and after that, stress-strain curve shows almost linear stress-strain relation. The strain at the center of the specimens (fiber discontinuity site) shows nonlinear stress-strain relation at relatively low stress range. After the strain away from fiber discontinuity rapidly increased, the stress-strain curves of both points almost agreed with each other. The nonlinear stress-strain relation at the fiber discontinuity site implies that interfacial debonding initiate and progress around the fiber discontinuity in the relatively low stress range. The coincidence of the stress-strain curves from the two points after the sudden increase in the strain implies the delamination development and progress between the continuous and discontinuous layers.