The influence of the interfaces on the fracture strain of fiber reinforced ceramic composites

In order to improve the fracture strain of fiber reinforced ceramic composites, it is necessary to understand how the fiber/matrix interface affects the fracture strain of the composite. Therefore, in this paper, FEM simulation using a cohesive zone model was applied to the issue. To discuss the realistic situation, we examined the influence of the fiber flaw on the fracture strain at first. Two cases were delt with : the flaw is considered in one case, not considered in the other case. The result shows that if there is the flaw in the fiber, it caused the stress concentration and invoked fiber break. This result suggests that the fracture strain will be overestimated if the flaw is not considered. Secondly, Sigma-fiber-reinforced glass-matrix composite was considered and how the fiber/matrix interface affects the fracture strain and fracture behavior was examined. Of particular note is that the stress concentration at the tip of interfacial deboding may invoke fiber break. As a result, it is necessary for the composite not only to form multiple-crack state but also to have weak interface enough for the stress concentration at the tip not to invoke fiber break.