Introduction

Abstract

During the past 25 years, the size of utility scale horizontal axis wind turbines grew uninterrupted, constantly seeking a reduction of the cost of energy, figure 1.1. As the rotor size increases, all wind turbine components, and the blades in particular, have to withstand higher loads. In the past, the higher structural requirements were mainly satisfied by up-scaling the load carrying components and thus increasing the weight of the structure, or by employing compounds with an higher specific strength - and cost. Sieros et al.