ABSTRACT
This chapter deals with the structural design of the rotor and tower for a horizontal axis wind turbine. This naturally follows from the aerodynamic design from which the aerodynamic loads are derived. As often happens in the design of aerodynamic systems, there needs to be a compromise between the aerodynamic optimum and the structural optimum. The latter seeks to optimize strength, weight and cost. There are four primary sources of loads that are relevant to horizontal axis wind turbines. These are aerodynamic loads, gravitational loads, dynamic loads, and control loads. Rotor vibration is an important aspect of horizontal axis wind turbines because the long blades are partially elastic structures that are continually subjected to unsteady and cyclic loads that can excite a natural vibratory response. The chapter shows that the wind turbines are designed to operate for a minimum of 20 year. Over this amount of time, wind turbines are exposed to a broad range of wind conditions.
