Simulation analysis of fatigue behavior of SiC fiber reinforced SiC matrix composites

The continuous carbon fiber reinforced silicon carbide matrix composite (SiC_f/SiC) has become an important thermal structural material for the next generation of aerospace engines due to its advantages of lightweight, high-temperature resistance, and high damage tolerance. However, the long fatigue test cycles and high costs severely limit the in-depth understanding and engineering applications of complex microstructures of SiC_f/SiC. To fully exploit the advantages and tunability of SiC_f/SiC, and to achieve the prediction of structural load response and optimization design, this study analyzed the fatigue life curves of unidirectional, orthogonal, and two-dimensional braiding SiC_f/SiC using fatigue hysteresis models and progressive damage theory. The sensitivity evaluations of SiC_f/SiC fatigue life were achieved by adjusting parameters such as interfacial shear stress (±20%), fiber strength (±5%), fiber Weibull modulus (±1%), and fiber volume fraction (±5%) through bias processing. The resulting upper and lower bounds of the fatigue life curves enveloped the primary experimental results. Based on the above analysis, a method for fitting fatigue life curves was verified, controlling hazard estimation and conservative estimation with damage parameters. The practicality of this method for practical engineering evaluation was demonstrated with simulated structures of SiC_f/SiC turbine blades.