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Title: Nonlinear Legendre Spectral Finite Elements for Wind Turbine Blade Dynamics: Preprint

This paper presents a numerical implementation and examination of new wind turbine blade finite element model based on Geometrically Exact Beam Theory (GEBT) and a high-order spectral finite element method. The displacement-based GEBT is presented, which includes the coupling effects that exist in composite structures and geometric nonlinearity. Legendre spectral finite elements (LSFEs) are high-order finite elements with nodes located at the Gauss-Legendre-Lobatto points. LSFEs can be an order of magnitude more efficient that low-order finite elements for a given accuracy level. Interpolation of the three-dimensional rotation, a major technical barrier in large-deformation simulation, is discussed in the context of LSFEs. It is shown, by numerical example, that the high-order LSFEs, where weak forms are evaluated with nodal quadrature, do not suffer from a drawback that exists in low-order finite elements where the tangent-stiffness matrix is calculated at the Gauss points. Finally, the new LSFE code is implemented in the new FAST Modularization Framework for dynamic simulation of highly flexible composite-material wind turbine blades. The framework allows for fully interactive simulations of turbine blades in operating conditions. Numerical examples showing validation and LSFE performance will be provided in the final paper.
Authors:
; ; ;
Publication Date:
OSTI Identifier:
1122309
Report Number(s):
NREL/CP-2C00-60759
DOE Contract Number:
AC36-08GO28308
Resource Type:
Conference
Research Org:
National Renewable Energy Laboratory (NREL), Golden, CO.
Sponsoring Org:
NREL Laboratory Directed Research and Development (LDRD)
Country of Publication:
United States
Language:
English
Subject:
17 WIND ENERGY; 97 MATHEMATICS AND COMPUTING NONLINEAR BEAM; FINITE ELEMENTS; WIND TURBINE BLADES; GEOMETRICALLY EXACT BEAM THEORY (GEBT); LEGENDRE; LSFE; BEAMDYN; Wind Energy