ABSTRACT
Material requirements concentrate on stiffness, density, and long time fatigue:
• High material stiffness supports aerodynamic performance • Low-density reduces gravity forces • Long fatigue life reduces material degradation
Design process focuses on the materials and the in—uence that technology has on the stiffness and strength of the materials. Development weightlength correlation is illustrated in Figure 3.1.1
Symbols indicate different manufacturers and processing technologies. Shown in the ¤gure, the blade length of 55 m weighs approximately 20 tons. The lower end of the curve represents the relatively short blades of lengths from 12 to 15 m. These were common in the early years of wind turbine design (1980s).
