抄録
The purpose of this paper is to examine the crack extension behavior in the brittle material under the compression mixed mode loadings. We here employ a cement paste as the brittle materials. An initial crack was inserted in the center of the disc-type test-piece. The compressive loads were obliquely applied to the initial crack. The extension phenomena of the crack were photographed by a high-speed video camera, and the image analysis was carried out. Using the result of the image analysis, we observed the crack extension behavior in the experiment in detail. It was confirmed that the cracks first occurred from the tips of the initial crack and the secondary cracks were observed after the first cracks. The experimental results were examined using the energy release rate criterion. As a result, the relations between the fracture load in the experiment and the loading angle were found to agree well with the relations between the energy release rate by the E-integral and the loading angle.
