The Penetration Characteristics of CF/Epoxy Curved Sheller According to Stacking Sequence

Carbon fiber reinforced plastics, among the advanced composite material watched with keen interests today, is widely used as structural components requiring light weight property because of its high specific strength as well as high specific rigidity. However, this material has a drawback of weakness against a transverse impact loading acting toward the direction of its stacked thickness, which requires different design parameters other than those used for general metal products in actual application. In connection with this point of view, this study utilized specimen of laminated composite material shell having certain radius of curvature considering actual structural component made of laminated CFRP composite material. Penetration experiment was conducted by measuring time of penetration of steel ball between two points where ballistic-screen sensors were attached on front and reverse side of the specimen with the air gun under air pressure that is adjusted by the pressure gauge attached to. Critical penetration energy was found by measuring kinetic energies of the steel ball before and after the penetration. In order to identify crack pattern and penetration mode generated inside the specimen after the experimental penetration, this study used digitalized optical microscope. Through this study, therefore, penetration characteristics by changes in number of layers, by different stacking sequences as well as penetration mode have been observed.