Papers by Author: Satoshi Hanawa

Abstract: Due to excellent high temperature resistivity on the strength, carbon fiber reinforced carbon matrix composites are thought to be one of attractive materials in a nuclear engineering field, e.g. the application to control rod sheath and so on in high temperature gas-cooled reactors as well as plasma facing components in fusion reactors. Prevention of the buckling fracture is placed as one of key subjects in the component design of C/C composites. The buckling fracture test was, therefore, carried out using 2-dimensional C/C composite (2D-C/C composite), and fracture surfaces were observed by SEM. From the buckling fracture test, it was found that there are three kinds of fracture modes; i.e. delamination fracture mode of fiber bundles at low aspect-ratio region, shear fracture mode of fiber bundles at middle aspect-ratio region and shear fracture mode of fiber bundles accompanying by fiber buckling at high aspect-ratio region.

Abstract: In the structural design of ceramics components especially for graphite materials, it is important to apply the realistic fracture model in the design method so as to reduce the large safety margin. In this study, we proposed the multiaxial strength model by expanding the microstructure based brittle fracture model applicable to both uniaxial tensile and compressive stress conditions. The advantage of the model is a treatment of the microstructural information such as grain size, pore size and pore size distribution. The proposed model was applied to biaxial strength prediction of near isotropic nuclear graphite using grain/pore related microstructure parameters. Predicted results were compared with biaxial strength data, and it was found that the proposed fracture model showed fairly good strength prediction.