Influence of fibre misalignment and voids on composite laminate strength

This article studies the effects of manufacturing defects of laminate composite materials on the first ply failure load and ultimate strength of the laminate, which are calculated using finite element modelling with Zinoviev's damage model. The following types of defects are considered for cross-ply and quasi-isotropic layups: in-plane misalignement and out-of-plane waviness of fibres, misorientation of the layers and void content. The list of laminates studied in this article includes cross-ply and quasi-isotropic layups, loaded in tension and compression in 0°, 90°, 45° and 5° directions. The limits of the first ply failure load and strength degradation for a realistic range of the defect intensities are estimated.