Evaluation of fiber‐matrix interphasial toughness in unidirectional composites

Abstract Interphasial toughness was evaluated for polyester and epoxy unidirectional glass fiber reinforced composites using single edge‐notched specimens. This was accomplished via a calculation of an energy term based on J‐integral which accounted for the energy required to form a longitudinal split crack ahead of the original notch. It was found that the fiber‐matrix interphasial fracture resistance of the epoxy composite is substantially greater than that of the polyester composite. This technique may be an excellent way of evaluating the interphasial quality in unidirectional composite laminates.