Interlaminar fracture behavior of quasi-unidirectional and angle-ply E-glass/polyester laminates loaded in model I, mode II and mixed mode were investigated. The layups were (0)_6, (+-30)_5. Special emphasis was put on the details of crack propagation. It was observed that the interlaminar crack front assumed a shape deviating from the ideal straight crack front. A modification of the data reduction scheme for fracture toughness was proposed. The curved crack front retained its shape at the increasing crack length and the corrected fracture toughness is less than that obtained using the traditional characterization. Angle-ply laminates have the higher mode II and mixed-mode toughnesses than unidirectional laminates. But the mode I toughness is approximately independent of the ply angle.
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