Fracture Behavior of Si-Ti-C-O Fiber/Munllite Matrix Composites under Anticlastic Bending Test

Tension-compression biaxial strength was measured by anticlastic bending test for the laminated Si-Ti-C-O fabrics (10vol%)/mullite matrix composite. Biaxial strength of composite material was lower than that of monolithic mullite ceramics. According to observation of the fracture patterns and fracture surfaces, we assumed the fracture process of the composites in anticlastic bending test to a as follows. Firstly, microcracks were generated by residual stress due to the difference of thermal contraction between mullite and fibers. Secondly, the microcracks propagated and connected to form macroscopic cracks on the surface of specimen by the shear stress of the anticlastic bending test. Finally, mode II fracture occurred from the macroscopic cracks in the direction perpendicular to the tensile principal stress.