Elastic Field and Frequency Variation in Extendable Wind Turbine Blades

Abstract

The behaviors of tip displacement, maximum stress, and natural frequency of vibration as a function of blade length are investigated for extendable wind turbine blades. A threedimensional linear elasticity finiteelement model of the blade is used along with a typical profile and representative material properties. The quasilinear response and free vibration behavior are investigated for a sequence of blade geometries. These estimates are intended to give approximate measures of expected changes in the elastic and dynamic field as the operating length changes and provide preliminary guidelines for this novel class of structure.