Open-hole tensile behavior in 2 × 2 twill woven carbon fiber reinforced composites

Abstract Carbon fiber reinforced polymer (CFRP) composites have become ubiquitous in industry due to their high strength-to-weight ratio, low density, excellent fatigue behavior, and impact strength. An endless combination of CFRP weaves offers tradeoffs between layup workability, isotropic versus anisotropic properties, and strength predictability. While unidirectional fiber laminate composites have been well-studied and predicted open-hole tensile strengths can be modeled with existing strength models, unique weave patterns require validation in their predictive models. In this study, 2 × 2 twill CFRP composites were characterized in terms of physical appearance, morphological, mechanical, and thermal properties. Furthermore, the effects of three different hole diameters and stacking sequences on the ultimate tensile strength of hole-drilled 2 × 2 twill CFRP composites were investigated. Tensile strength values were also predicted by three predictive strength models: “Point Stress Criterion (PSC)”, “Average Stress Criterion (ASC)”, and “Modified Point Stress Criterion (MPSC)”. MPSC was found to be the most adaptable model, as it integrates additional fitting parameters, enabling it to predict strength with high accuracy for different orientations. These models were fitted to experimental data for each laminate having different hole diameters.