On the interlaminar fracture behavior of carbon/epoxy laminates interleaved with fiber‐hybrid non‐woven veils

Abstract

AbstractThis study investigates the effect of fiber‐hybrid non‐woven veils on the interlaminar fracture of out‐of‐autoclave carbon/epoxy laminates. The Mode‐I and Mode‐II interlaminar toughening performance and R‐curves behavior of out‐of‐autoclave composite laminates with carbon and thermoplastic fiber‐hybrid veils are investigated. Pure carbon veil (i.e., high‐stiffness fibers), pure polyphenylene sulfide veil (i.e., low‐stiffness fibers), and three variants of fiber‐hybrid carbon/polyphenylene sulfide veil with different fiber contents (i.e., combination of low‐ and high‐ stiffness fibers) are tested and compared for Mode‐I and Mode‐II interlaminar toughening performance. All the pure and fiber‐hybrid non‐woven veils used in this study have a fixed areal density (~20 g/m2). Resin infusion combined with out‐of‐autoclave curing is utilized to manufacture the laminates. The results show that the hybridization of carbon fibers with thermoplastic fibers can address the observed shortcomings of the pure carbon veils (i.e., unstable crack growth) and of the pure thermoplastic veils (i.e., falling R‐curve) in toughening interlaminar regions. Considering both the Mode‐I and Mode‐II interlaminar fracture behavior, it is shown that fiber‐hybrid non‐woven veil toughening offers rising R‐curves, constrained crack paths (inside the veil), and enhanced interlaminar fracture energies, which are desirable for structural applications.Highlights Pure carbon/thermoplastic veils have shortcomings in interlaminar toughening. Hyrid veils constrain crack path and offer rising R‐curve. The weight ratio of hybrid veils affects crack paths and R‐curves.