一方向強化Si-Ti-C-O繊維結合型セラミック複合材料の引張破壊過程の観察とシミュレーション( 実験計測技術の新展開)

The observation of tensile fracture process of unidirectional Si-Ti-C-O fiber-bonded ceramic composite at room temperature revealed the fracture behavior as follows : First breakage of matrix initiated at the strain level of about 0.2%. Then, the number of matrix cracking increased with increase in strain. In spite of the cracking of matrix, the interfacial debonding was suppressed by the compressive residual stress of the matrix. The slope of the stress-strain curve scarcely decreased from the initial one because of high fiber volume fraction (0.9) and redistribution of stress caused by suppression of debonding. Breakage of fibers occurred just before fracture. Once it occurred, large scale debonding was caused owing to the tensile residual stress of fiber. Finally, overall fracture of the composite occurred, accompanied by a large number of fiber breakage. A simulation of the fracture process was performed using the modified shear lag analysis combined with the Monte Carlo method. The characteristics of the fracture process observed in experiments could be reproduced fairly well by this method.