Composite materials for wind energy applications

Abstract

Weight and strength of materials are important in design for wind energy and aerospace industries. It is a major advance to design new materials for these kinds of applications to achieve high efficiency reducing weight. Sandwich composites and Fibre Metal Laminates (FMLs) are outstanding materials owing to superior mechanical properties. However, they need to be evaluated under static and dynamic loading to which these kinds of applications are subjected. The purpose of the thesis is the investigation of sandwich composite and FMLs for wind turbine blade and aerospace structure evaluating Digital Image Correlation (DIC) and modelling of sandwich composites and FMLs to provide an insight into the failure processes in these materials. In this thesis, sandwich composites with four different core materials and five different surface finishing options were studied. There are advantages in having a softer core near the outer surface to improve impact and mechanical performance and grooves in the core are used to improve resin infusion and draping for curved structures. For the sandwich composites investigated, PVC and PET foam cored sandwich composites can be a substitute foam core material especially for wind turbine blades instead of using balsa cored sandwich composite. In addition, saw-cut (foam is partially cut) and flexi-cut (with grooves on both sides) are surface finishing options often employed to improve the energy absorption and increase the flexural behaviour in a beneficial way. The behaviour of curved sandwich composites was also assessed. In addition, FMLs with three different metal and three different design configurations have been evaluated. The most important parameter for the FMLs are the thickness when considering flexural and impact response of the FMLs. Both of these studies can be guidelines for designing materials for wind turbine blade and aerospace applications to decrease structure weight and increase the mechanical strength of the structure.