抄録
The application of high-temperature and high-strength ceramic matrix composites (CMCs) to engine components, which is necessary for improving the fuel economy of aircraft, necessitates the enhancement of material properties and accurate predictions of structural strength. A comprehensive understanding of the mechanisms underlying fractures is crucial for accurate strength predictions. This study builds on a static tensile model for unidirectional CMCs, accounting for matrix cracks and fiber breakage, and on energy-based matrix and transverse crack growth models for cross-ply CMCs. Here, a novel periodic crack growth model that represents variations in the matrix and transverse crack growth was devised. In addition, a fiber breakage model was developed to account for the local effects in the vicinity of broken fibers and initial fiber damage. The stress–strain relationships and crack-density growth processes of unidirectional and cross-ply CMCs were compared through experimentation and analysis using the two aforementioned models. The local load-sharing model, which considers the local effects of broken fibers, could accurately represent stress–strain relationship in unidirectional CMCs, and the stress–strain relationship in cross-ply CMCs was accurately represented by adjusting the fiber breakage probability associated with matrix cracks rather than the initial fiber damage. The proposed models could quantitatively express the matrix crack density–strain relationship, and they accurately represent the trends of the transverse crack density–strain relationship.
