平織炭素纖維强化複合材料의 원공노치 補强部에 關한 强度評價

Abstract

In recently years, there have been rapid technological developments in the field of application of woven composites. The CFRP(carbon fiber reinforced plastics) composite material has unique properties that offer high strength and stiffness, even though it has light weight. Therefore it can be used in many applications such as ship, transportation, aerospace and electronic fields. As usage composite material is increasing, it is necessary for structure of safety assessment using composite material. Here the circular hole was repaired with the repair element material. And then, failure behaviors were compared by two kinds of cases. The aim of this work is to evaluate fracture behavior and patterns of plain woven CFRP with the repaired circular hole. The employed materials are CF 3327 EPC(t : 0.27mm), plain woven carbon prepreg of Hankuk Carbon Co. The tensile test specimen end tabs adhered to aluminum tabs with the araldite comprised of the epoxy resin prevented to the damage from the tester grips. The specimen plates were repaired by one or both sides. Specimens of the circular diameter (3, 4 and 5mm) were examined. The tests were carried out by means of universal dynamic tester (50kN H. Co.). The test was accomplished with displacement control in 1.0mm/min at the room temperature. The damage in the vicinity of repaired were monitored by using VCD camera (SAMSUNG KENOX V20) and were compared with load-displacement curve. For the plain woven CFRP composite, the strength characteristics according to the repaired circular hole. The following conclusions could be drawn from this study. (1) In case of being repaired one side to composite with a 3mm, 4mm and 5mm of circular hole's diameter results in load rise effect of 13.35%, 17.06%, 19.35% respectively, and both sides 29.06%, 33.75%, 35.65% respectively. (2) In case of being repaired one side to composite with a 4mm of circular hole's diameter which has a width to length of 25mm×35mm, 25mm×45mm results in 30.53kN, 32.97kN respectively, and both sides 34.46kN, 36.54kN respectively. (3)In case of being divide repaired plate's area into a 4mm of circular hole's area results in area ratio of 49.76, 69.67, 89.57 respectively. And this shows that repaired effect is larger as area ratio of repaired plates increase. (4) In case of being repaired circular hole with a mixing of one side and both sides results in the form that it is either separated of repaired part or ruined it with specimen simultaneously.