ANALYTICAL STUDY OF STRESS FIELDS IN WIND TURBINE BLADES

The thesis aims at shedding light on the difference in the stress distribution between prismatic and non-prismatic beams. The approach strategy has being that of drastically simplifying the initial problem in the attempt to identify the relevant governing parameters. The geometry of a real wind turbine blade has been first drastically simplified: from the multi-cellular airfoil to a box girder and to a single web panel. Once solved the simplest problems, the intention has been to gradually reintegrate the complexity of the problem with the aim of applying the obtained results to a real wind turbine blade. The thesis consists of three parts. In the first part some brief information on the technology of wind energy and wind turbines are given. Also, the state of the art of the modeling of non-prismatic beams is discussed, with a particular focus on tapered beams. After some first remarkable results obtained at the beginning of the 20th century, the literature survey shows that only in recent years it has been an increase of interest on the subject. In the second part all the theoretical details that lead to the approach that is subject of the present thesis are deepened. In the third part the results of the application of the strategy proposed to both elementary and more complex geometries are shown, and the final remarks on the 10MW wind turbine blade are discussed.