Interlaminar shear behavior of thick carbon/epoxy composite materials

Abstract

The interlaminar shear behavior of thick carbon/epoxy composite laminates was investigated using the Iosipescu shear test. In order to manufacture thick test specimens, both the conventional autoclave cure cycle recommended by prepreg manufacturer and the modified autoclave cure cycle incorporating cooling and reheating steps were used. A 3-dimensional linear finite element analysis was performed to assess the uniformity of the shear stress field in the test section as well as to predict the failure mode of the specimen. For more accurate analysis of the stress field, contact elements were used between the specimen and the fixture, and the shear stress field in the thickness direction was taken into account. From the analysis, the failure region in the specimen was predicted and the correction factor was calculated to compensate for the non-uniformity of the shear stress field in the gage section. From the shear test, the interlaminar shear strength and shear modulus were obtained, and the interlaminar properties of the specimens manufactured by the conventional autoclave cure cycle were compared with those of the specimens manufactured by the modified autoclave cure cycle.