Fatigue damage mechanisms and constitutive modeling of C f /SiC ceramic matrix composites: A review

C f /SiC composites combine low density and high specific strength with excellent mechanical performance at elevated temperatures, making them promising materials for load-bearing aerospace hot-section components. Under high-temperature cyclic loading, matrix cracking, interfacial degradation, fiber failure, and oxidation interact in a coupled manner, limiting their in-service reliability. This paper reviews the fatigue-damage mechanisms and corresponding constitutive models of C f /SiC. Unlike previous reviews, this work maps published experimental observations to model state variables and evaluates the availability of data required to identify model parameters and the applicability of these models at elevated temperatures. First, the paper analyzes matrix cracking, interfacial debonding and sliding, and fiber failure behavior during uniaxial tensile testing. Subsequently, tension-tension fatigue results obtained at different temperatures, in different atmospheres, and under different loading conditions are synthesized to identify characteristic features, including oxidation along cracks, interfacial sliding, hysteresis-loop evolution, and fiber-bundle instability. Models of matrix multiple cracking, statistical fiber failure, and interfacial damage are then assessed, and criteria for model selection are provided based on data availability. A comprehensive analysis indicates that effective high-temperature fatigue models require damage variables that can be measured directly or inferred reliably and must distinguish cycle-dependent interfacial wear from time-dependent oxidative degradation. The review provides guidance for C f /SiC high-temperature fatigue-test design, model selection, and reliability assessment of hot-section components.