AbstractsEngineering

The requirement for lightweight structures with high stiffness has seen the use of composite sandwich panels in many engineering applications. In recent years, foam cores have increasingly been used in composite sandwich constructions due to their ease of manufacture and low cost. However, their performances are often limited by their vulnerability to skin-core debonding. The shear-key methodology proposed in this thesis is a simple and cost-effective way of improving the shear resistance of foam-core composite panels and reducing the probability of their failure at the skin-core interface. This research is aimed at investigating improvements that can be achieved using shear keys and the influence of geometric parameters on the shear resistance of foam-core sandwich panels. The panels employed have glass fibre-reinforced polymer skins and polyvinylchloride and polyurethane foam-core materials while the shear keys are made from chopped strand glass fibres impregnated with epoxy resin. The effect of a shear key’s diameter, pitch and orientation in a sandwich panel subjected to shear loading is first investigated numerically using finite element modelling. Then, the model with the most promising shear-key geometry is fabricated and tested experimentally under shear loading and shows good agreement with the numerical results. In general, the panels with shear keys show stronger and more stable responses than those without them. Improvements in the flexural responses of sandwich panels through the introduction of shear keys are investigated both numerically and experimentally. Also, a theoretical model for the analyses, which takes into account the appreciable shear deformation in the core, is developed and found to provide predictions in good agreement with the numerical and experimental results. These theoretical, numerical and experimental studies confirm that foam-core sandwich panels with shear keys exhibit better flexural performances than ordinary panels without shear keys. From this study, it is concluded that incorporating shear keys with appropriate geometry in foam-core sandwich panels provides significant improvements in both shear and flexural performances.