Verification and validation of the geometrically exact beam theory with Legendre spectral finite elements for wind turbine blade analysis, A

Abstract

Composite wind turbine blades continue to get larger and have more complex geometry than ever before. Additionally, they are becoming lighter in proportion to their size. Lighter and larger wind turbine blades result in structures that are highly flexible. It is necessary to have computer aided engineering (CAE) tools that are capable of modeling the nonlinear behavior of composite structures with complex geometry in a robust yet computationally efficient manner. The National Renewable Energy Laboratory (NREL) has developed an aeroelastic CAE tool, FAST, which is used for wind turbine analysis. The current wind turbine blade model in FAST is based on linear Euler-Bernoulli beam theory. A new finite element beam model, BeamDyn, which is based on the geometrically exact beam theory (GEBT) has been proposed to replace the incumbent wind turbine blade model in FAST. In the work reported here, GEBT and its spectral finite element implementation in BeamDyn is presented, and a number of numerical and experimental cases show the efficacy of the proposed model.