ABSTRACT
This chapter focuses on the rotor blades, which probably present the most challenging materials, design and engineering problems. The early composite materials for rotor blades were glass fibres combined with polyester, a material, as well as a processing method, taken from the boat industry. Wood is a natural material and thus environmentally attractive, but at the same time difficult to obtain in reproducible and high quality, which is a requirement for stable and economical manufacturing of rotor blades and thus economically attractive wind energy. The combined materials performance criteria identify the candidates for rotor blades as woods and composites. The wind turbine blades are designed toward stiffness and fatigue. Hence, the materials required for the blades are materials with a very high performance. Their exceptionally high stiffness-to-weight and high strength-to-weight ratios, together with an excellent fatigue performance, are the reasons for composite materials being the dominant choice.
