スマートＣＦＲＰ構造開発を目的とした電気ポテンシャル法による層間はく離検出法の適用性検討

Abstract

CFRP composite plate structures have been generally known as that those have high specific mechanical properties. The CFRP composite plate, therefore, has been widely applied to many kinds of aircraft structures. The composite plate structures, however, have a week point at interlamina strength. Since a delamination resistance of its plate is very low, delaminations easily yield by a low velocity impact loading or fatigue loading. For this reason, a smart structure to detect a delamination is desired now. In this study, therefore, an applicability of an electrical potential method to detect a delamination was examined experimentally from a stand point of a sensor for a smart structure. Effects of prepreg thickness, kind of electric current of electrical resistance bridge, loading mode and stacking sequence were all experimentally researched by using T 300/Epoxy. Mode I and II types of tests were conducted and the electrical resistance changes were measured by the electrical resistance bridge circuit. As a result, the followings were obtained. (1) In the case that there are many interlaminae by using thin prepreg sheet, the electrical resistance change is smaller than that of thick one because the electrical resistance to the plate thickness becomes large. (2) The AC is better for an electrical resistance bridge circuit than DC because it gave more stable results than those by DC. (3) Though the delamination crack surfaces contact with each other in the mode II tests. The electrical resistance change could be measured by the AC electrical resistance bridge method. (4) In the actual composite, plates, the nonlinear relations between the delamination crack growth and the electrical resistance of the specimen were obtained due to the delamination crack plane transition.