Observation and analysis of fracture process of fibre, matrix and interface in UD Si-Ti-C-O fibre-bonded composite

The detailed observation of fracture process of unidirectional Si-Ti-C-O fibre-bonded ceramic composites at room temperature revealed the fracture behaviour as follows: first, matrix crack initiated at the strain level of about 0.2%. Then, matrix cracks accumulated with an increasing strain. In these processes the interfacial debonding was suppressed by the thermal compressive residual stress of the matrix. The slope of the stress-strain curve scarcely decreased from the initial one because of the high fibre volume fraction (around 0.9) and of the suppression of debonding. The breakage of fibres, followed by large scale interfacial debonding, occurred just below the ultimate load. Then, overall fracture of the composite occurred, accompanied by a large number of fibre breakage. A simulation of the fracture process was carried out using the modified shear lag analysis combined with the Mote Carlo method. The characteristics of the fracture behavior observed in experiments could be simulated fairly well by this method.