Prediction of Residual Tensile Strength after Fatigue in Unidirectional Brittle Fiber-Reinforced Ceramic Composites

Abstract

This paper presents models for predicting residual tensile strength after fatigue in unidirectional brittle fiber-reinforced ceramic composites. First, the subcritical crack growth law was employed to predict residual strength of fiber. Next, two models were proposed for residual strength of a composite. The first model, Model I, is established based on Curtin's probabilistic model that describes the relationship between strengths of the fiber and the composite. In the second model, Model II, the composite strength is directly derived from the survival probability of fiber. Thirdly, the relationship between lives of the fiber and the composite was investigated. Finally, a case study was conducted for a ceramic matrix composite (CMC) to obtain the residual strength of the CMC after static fatigue loading. It was proven that the life and the initial strength of the fiber and the composite depend on the shape parameter of fiber strength and the fiber/matrix interfacial shear stress. In contrast, the residual strength ratio of the composite was found to be almost independent of these two parameters.