Effects of Stacking Sequence on Notched Strengths of Cross-Ply CFRP Laminates and Analysis Using a Cohesive Zone Model

Effects of the thickness of plies of the same orientation on the notched strength of symmetric cross-ply CFRP laminates are examined. Three kinds of symmetric cross-ply CFRP laminates with the same total number of plies and the different number and sequence of adjacent laminae of the same orientation are used. Notch sensitivity of those laminates is evaluated for different shapes of notches: double-edge notches (DEN) and a center open hole (CH). Validity of an analytical cohesive zone model (CZM) is evaluated by comparing with experimental results on the three kinds of cross-ply laminates with a center hole. It is clearly observed that the tensile fracture strengths of the DEN and CH specimens significantly reduce as the notch size increases. The sensitivity to notches is highest in the case of alternating cross-ply configuration. The results of this study suggest that additional energy dissipation due to damage around notches should appropriately be considered to estimate the effective fracture toughness used in CZM calculations, especially for a class of cross-ply laminates with lower notch sensitivity.