Fiber Matrix Interface Effects in Failure of Ceramic Matrix Fiber Composites

摘要

Macroscopic and microscopic mechanical properties of ceramic composites have been investigated. A general analytical expression was obtained for the steady-state matrix cracking stress in composites that fail noncatastrophically. The solution is expressed in terms of the stress-displacement relation that characterizes stretching of the fibers between the crack surfaces, and is applicable to any reinforcement that forms crack bridging ligaments, including ductile reinforcements. The influence of statistical distributions of fiber strengths on nonsteady-state and steady-state matrix cracking, as well as on transitions in failure mechanism between catastrophic and noncatastrophic modes, has been evaluated. The indentation fiber-pushing technique that was developed previously under this contract for measuring fiber-matrix interfacial properties has been further extended to allow measurement of residual stresses in individual fibers. (JES)