Development of a Fiber Bundle Cell Framework for Rapid, Reliability‐Based Analysis and Design of Pseudo‐Ductile Thin‐Ply Hybrid Composites

ABSTRACT In this study, we developed and validated a novel fiber bundle cell (FBC) framework to enable rapid, reliability‐anchored design of pseudo‐ductile thin‐ply carbon/glass hybrid composites. The objectives were to formulate a stochastic, yet computationally efficient, model that reproduces pseudo‐ductile tensile behavior and its scatter, and to derive probability‐based design criteria that guarantee monotonic, plateau‐like responses at prescribed confidence levels. In addition, we demonstrated the applicability of the model by reevaluating published results to show how much extra information can be obtained by FBC‐based decomposing. The methodology adapts a linear E‐bundle FBC representation composed of parallel elastic bundles with statistically distributed stiffnesses and breaking strains, which are calibrated directly from mean and standard deviation data. Closed‐form expressions for expected stress and its standard deviation were derived, and classical strength ratio and mode‐II toughness criteria were recast in probabilistic form. We validated the model predictions against reevaluated thin‐ply tensile tests published earlier: the FBC accurately reconstructed the mean pseudo‐ductile plateau (error < 5%), achieved RMSE = 3.06% and R 2 = 0.9894 for curve fits, reproduced the non‐monotonic evolution of scatter (including observed negative correlations due to fiber pull‐out and confined delamination), and delivered lower‐tail quantiles for ductility and interfacial toughness. The findings establish the FBC as a physically interpretable tool for strain‐resolved design and reliability assessment, demonstrating how it can provide additional and more profound knowledge about pseudo‐ductile behavior compared to the original evaluation. Potential applications include damage‐tolerant primary structures in any safety‐critical composite application requiring predictable, non‐catastrophic failure margins.