Predicting tensile behaviour of plain weave CMCs using a nonlinear data-driven constitutive model for fibre tow composites

The paper explores the tensile behaviour of plain weave ceramic matrix composites (CMCs) by employing a nonlinear constitutive model for fibre tow composites, driven by in-situ X-ray computed tomography data. Through the application of a deep-learning-based image segmentation method, the study successfully identified material damage modes, including matrix cracks, fibre pull-out, and interface debonding. Three-dimensional characterisation and quantitative analyses of damage have been conducted. At the mesoscopic level, a theoretically derived nonlinear constitutive model for fibre tow composites, accounting for continuous damage to both fibre and matrix, is established by using damage data. At the macroscopic level, a unit cell model is constructed for the numerical simulation of plain weave CMCs. Material's initial defects are prone to induce crack initiation. External matrix cracks can propagate to tows, and crack deflection may occur during this process. Furthermore, adjacent microcracks have the potential to connect, forming a larger one under high stress. Theoretical results predicted by the nonlinear constitutive model for fibre tow composites under tension exhibit good agreement with test data. The built unit cell model accurately predicts the tensile mechanical behaviour of plaine weave CMCs.