Bending Failure Behavior of UD ‐ CF / PEEK Laminates: A Multiscale Analysis Considering Microstructural Imperfections

A multiscale analysis was performed to investigate the bending failure behavior of unidirectional carbon fiber‐reinforced polyetheretherketone (UD‐CF/PEEK) laminates. Representative volume element (RVE) models incorporating different microstructural imperfections, including fiber strength dispersion, initial fiber misalignment, and spatially non‐uniform fiber distribution, were established to obtain homogenized mechanical properties under different loading conditions. An equivalent macroscopic model combining the Hashin failure criterion with displacement‐based stiffness degradation was subsequently developed to predict progressive bending failure at different span‐to‐thickness ratios. The RVE models reproduced the elastic properties, ultimate strengths, and corresponding failure patterns, with an average prediction error of 5%. At the macroscale structural level, the homogenized model accurately reproduced the load–displacement responses and progressive damage evolution under both short‐beam and three‐point bending. The predicted short‐beam strength differed from the experimental value by 4%, while the predicted flexural modulus and strength from three‐point bending showed errors of 3% and 11%, respectively. These results demonstrate that accurate representation of microstructural imperfections and geometry, together with appropriate nonlinear constitutive behavior and stiffness degradation model, is critical for accurately predicting the mechanical response and progressive failure of composites.