Theoretical models and influencing factor analysis for the temperature-dependent tensile strength of ceramic fibers and their unidirectional composites

In this paper, two physics-based temperature-dependent strength models for ceramic fibers were presented based on a critical failure energy density theory. These models included the combined effects of temperature, phase composition and oxidation on ceramic fiber strength. Good agreement between the model predictions and the experimental results was obtained. Based on the above models and the Cao and Thouless's theory, a new temperature-dependent strength model for unidirectional ceramic fibers reinforced ceramic-matrix composites was developed. The good agreement between the predicted results and the experimental data fully validates the reasonability of this model. Compared with the Cao and Thouless's model, the model is more practical and convenient to predict the temperature-dependent tensile strengths of the composites. The influencing factor analysis for ceramic fibers and their unidirectional composites were systematically conducted. Some new findings regarding their temperature-dependent tensile strengths were provided for the first time.