ABSTRACT Carbon fiber fabric‐reinforced polyetheretherketone (CFF/PEEK) composites are promising for lightweight applications, yet their damage tolerance remains difficult to predict because of microstructural heterogeneities introduced during manufacturing. To address this, a process‐oriented multiscale modeling framework is developed. Experimentally measured through‐thickness mesostructural gradients are incorporated into layer‐specific representative volume elements (RVEs). Yarn properties are homogenized from microscale RVEs that account for porosity and interfacial effects. A modified Linde failure criterion, enhanced with a shear contribution coefficient, is introduced to capture shear‐tension coupled damage in yarns. The framework is validated through an integrated experimental‐numerical approach using digital image correlation (DIC) and scanning electron microscopy (SEM). Results show that the layered RVE model predicts damage initiation and progression with significantly higher accuracy than homogeneous models. Under 0° tension, simulations reveal that damage initiates in near‐surface plies and propagates inward, with the corresponding damage modes corroborated by SEM fractography. Under 45° off‐axis loading, the evolution of strain fields from DIC and fracture morphology from SEM jointly validate a three‐stage damage competition mechanism governed by shear‐tension coupling and matrix‐interface interaction. Furthermore, the analysis quantifies that porosity severely degrades matrix‐dominated properties, while interfacial strength critically governs off‐axis performance.
Li et al. (Sat,) studied this question.