Abstract
Static tensile test and in-situ observation of unidirectional Si-Ti-C-O/BMAS (barium magnesium aluminosilicate glass) composite materials were carried out at room temperature in order to clarify the fracture behavior in mesoscopic scale. In-situ observation showed the fracture behavior as follows: First breakage of matrix initiated at the place where fiber-spacing was wide at the stress level of about 200MPa. Then, the number of matrix cracking increased with increase in strain. As a result, the slope of the stress-strain curve decreased from the initial one. In spite of cracking of matrix, the interfacial debonding was suppressed by the compressive residual stress of the matrix. Breakage of fibers occurred when the stress of composite reached about 90% of its fracture strength. Once it occurred, large scale debonding was caused due 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 Mote Carlo method. The characteristics of the fracture process observed experimentally could be simulated fairly well by this method.
