Comparative Assessment of Finite Element Modeling Methods for Wind Turbine Blades

Significant growth of the wind energy industry over the last two decades has driven rapid evolution of wind turbine technology leading to dramatic increases in wind turbine rotor size and power ratings which continue to stretch the limits for materials and blade structural design. Historically, wind turbines have been analyzed using cross-sectional analysis with large safety factors. Modern approaches to blade design incorporate 2D layered-shell finite element modeling for structural analysis but rely on simplifying assumptions to represent a turbine blade. More recently, high-fidelity modeling including non-linear analysis, solid elements, and higher order elements has been suggested in the literature, resulting in an extensive array of recommended modeling practices without a clear consensus on the appropriate modeling fidelity to analyze a blade or under what circumstances higher fidelity methods are warranted. Meanwhile, the current certification standards allow a wide range of acceptable modeling methods, with minimal details on what constitutes a suitable analysis approach. The objective of this research is to critically assess modeling techniques for structural analysis of wind turbine blades in order to identify the appropriate level of fidelity and corresponding choice of safety factors for structural analysis of wind turbine blades. Additionally, this work seeks to evaluate the variation in modeling accuracy for the range of component thicknesses along the span of a typical blade in order to identify the conditions under which lower fidelity methods are inadequate. A review of recommended modeling approaches from literature in the wind industry has led to the selection of eighteen modeling approaches considering layered-shell and various solid element types, several element formulations and plate theories, smeared and discrete ply representations, linear and nonlinear solutions, and through thickness discretization of the solid models. The reference modeling method selected to evaluate these eighteen ...