自己治癒セラミックスの保証試験に関する有限要素解析

抄録

Ceramic materials are superior to metallic materials in variable respects such as lightness, strength, corrosive and thermal resistance and so on. Therefore, they are expected to be used as structural materials. However, internal and surface defects of them generated during manufactural processes could cause rapid crack growth and fracture. Thus, there is significant scatter of fracture strength even if manufactured in the same condition. This is the most serious obstacle for the practical use of ceramics. To resolve such a matter, the method in which “self-healing” and “proof test” are combined is suggested. It is known that Al2O3/SiC composite ceramics shows self-healing behavior using oxidation reaction under high temperature environment. It will be possible to remove the surface defects with this performance. After heat-treating surface defects, components which satisfy the required strength could be picked up with the proof test. In this study, we conducted the finite element analysis of treating surface defects and three-point bending proof test by using the damage-healing constitutive model based on the oxidation kinetics. In addition, we evaluated the scatter of bending strength with the Weibull distribution. In the analysis, we used specimens which have pre-cracks and internal defects to represent the competition between these defects. Finally, we demonstrated that how proof test condition depends on the self-healing conditions and microstructure.