Compressive behaviour of large undamaged and damaged thick laminated panels

Both intact and impact-damaged laminated panels under in-plane compressive loading are investigated with a purpose-built anti-buckling support. The readings of back-to-back strain gauges of selected locations are used to deduce panel behaviour in addition to post-mortem observation. The compression failure of intact panels is found to be close to the potted end. The failure characteristics of impact-damaged panels are dependent slightly on composite systems although they all failed in compression in the impact-damaged region with a kink shear band passing through the mid-section. E-glass/polyester panels with a greater shear angle do not seem to involve global buckling like S-glass/phenolic panels with small shear angles. The fact that the region covered by a kink shear band from impact surface to the distal surface is considerably less than the delamination area suggests that the initiation of overall failure is due to the collective result of flexural stiffness reduction compounded by the local impact damage and the associated change of fibre curvature. As a result, the residual compressive strengths are reduced significantly. Further outward propagation of the existing delamination(s) along the mid-section during loading is visible only for E-glass/polyester panels but is not significant.