二次元多結晶体における微視破壊過程のシミュレーション

概要

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Microfracture processes of microcracking and crack propagation are simulated for 2-dimensional alumina polycrystals which have thermal anisotropy within a grain. Microcracks are generated by the thermally induced residual stresses at a grain boundary. The stress concentration near the microcrack is calculated numerically by the body force method, and superposed on the pre-existing residual stress. Stress intensity factors at the microcrack tip are also obtained by the method, and the location at which the next microfracture occurs is determined by the competition between the microcracking and the crack propagation in the new stress state. The microfracture stress increases with the progress of the fracture and decreases after maximum indicating a fracture strength. In many cases, the propagation of microcracks induces an unstable fracture. The number of microfractures prior to the unstable state decreases with decreasing grain size and increasing grain boundary toughness. For the alumina of the grain size of 17.5μm, when the fracture toughness of the grain boundary is 0.6 times that of the grain or greater, the unstable fracture occurs prior to microcracking process.
一般社団法人日本機械学会の論文
1996-01-25