Experimentally-Parameterized Multiscale Fatigue Modeling of a 3D Woven SiC/SiC Composite at High Temperatures

Abstract

This study presents an experimentally-parameterized multiscale fatigue life prediction framework for a specific three-dimensional (3D) woven silicon carbide fiber-reinforced silicon carbide (SiC/SiC) ceramic matrix composite operating in high-temperature oxygen-free environments. The principal novelty of this work lies in the systematic application of such a framework to this particular material system, wherein most of critical geometric and material parameters at both the fiber yarn (microscale) and woven architecture (mesoscale) levels were quantitatively determined through direct experimental measurement. Key parameters were characterized using high-resolution X-ray computed tomography (X-ray CT) for precise geometric reconstruction of the crimped warp, weft, and stitching yarns. At the yarn level, a periodic micromechanical unit cell incorporating anisotropic continuum damage mechanics and Miner’s cumulative fatigue criterion was formulated to capture progressive stiffness degradation, matrix microcracking, and interfacial debonding under cyclic thermomechanical loading. The evolving yarn-level constitutive properties were then mapped as spatially-dependent inputs into a 3D representative volume element (RVE) that explicitly resolves the experimentally-characterized woven preform architecture. This coupled approach enables direct simulation of damage initiation, trans-yarn propagation, and ultimate fatigue failure. The framework was validated against tension-tension fatigue tests conducted at 1100 °C in a vacuum-nitrogen environment, demonstrating excellent predictive accuracy for fatigue life and damage progression mechanisms.