Rupture simulations for unidirectional ceramic matrix fiber composites

A model for the behavior of unidirectional fiber reinforced ceramic matrix materials with weak interfaces is used to simulate the stochastic failure process leading to ultimate stress and the transition to pullout controlled extension. Brittle cracking of the matrix is assumed to limit the axial load sustained by the matrix, does not damage the fibers, but allows the matrix to retain shear stiffness. Fiber element fracture nuclei consistent with a Weibull distribution of strengths fail stochastically with increasing load. Fiber-matrix load transfer at fiber failure sites is governed by uniform shear strength representing frictional constraint at unbonded interfaces. The results prior to peak load ale shown to be consistent with sparse fiber damage with modest stress concentrations on neighboring fibers. Localization is shown to dominate the post peak pullout.