Failure prediction in a non-crimp basalt fibre reinforced epoxy composite

Failure analysis in non-crimp fabric (NCF) based fibre reinforced composite materials is challenging due to the complexity associated with multiaxial fabric architectures and the interaction of different failure modes. In this study an in-situ 3-point bend test under scanning electron microscopy (SEM) has been performed to analyse the failure behaviour of a NCF basalt epoxy composite manufactured by vacuum assisted resin transfer moulding (VaRTM) technique. The failure mechanisms observed during the in-situ 3-point bend test are compared to those from standard (ex-situ) flexure and interlaminar shear strength (ILSS) tests on the same material. Finite element analysis of each test configuration is also conducted to analyse the in-ply stress distributions and to predict the damage initiating stresses. The study reveals that fibre/matrix debonding leading to matrix cracking in the 90° sub-ply is the damage initiating failure mode, with final failure occurring due to fibre buckling in neighbouring 0° sub-plies. The finite element analysis reveals that matrix cracking in the 90° sub-ply is controlled by shear stresses ranging between 35 and 45 MPa.