Abstract
In the projects Smartblades and Smartblades 2 a full-scale 20 m rotor blade for the NREL CART3 wind turbine was designed, built and tested. The rotor blade was intended to have a strong bending–torsion coupling. By means of the experiments, the proof for the technology in question was supposed to be provided. The experimental work was accompanied by simulations. The aim of the paper was to describe and publish a reference finite element model for the 20 m rotor blade. The validation procedure is presented, as are the modelling strategy and the limitations of the model. The finite element model is created using quadratic finite shell elements and quadratic solid elements. Different data sets were used for the validation. First, the data of static test bench experiments were used. The validation comprised the comparison of global displacement and local strain measurements for various flap and edge bending tests and for torsion unit loading tests. Second, the blades’ eigenfrequencies and eigenvectors in clamped and free–free scenarios were used for validation. Third, the mass distributions of the finite element and real blade were investigated. The paper provides the evaluated experimental data, and all analysed scenarios and the corresponding finite element models in Abaqus, Ansys and Nastran and formats as a reference dataset.
Highlights
The trend in designing larger and larger horizontal axis wind turbines (HAWTs) seems to be still unbroken if one looks into the current developments and announcements in the offshore and onshore markets [1] and at the research [2]
Due to the orientation of the rotor blade and the loading in edgewise direction, it can be expected that the mechanical strains at leading and trailing edge are higher compared to the spar cap strains
The validation was based on mass distribution data and static and modal test data
Summary
The trend in designing larger and larger horizontal axis wind turbines (HAWTs) seems to be still unbroken if one looks into the current developments and announcements in the offshore and onshore markets [1] and at the research [2]. This cost of energy- driven development comes with different challenges, as described in [3]—in particular, the precise prediction of the aeroelastic behaviour and the overall dynamics of a turbine equipped with large and very flexible wind turbine blades. Considering current medium large wind turbine blades of more than 60 m in length, where, e.g., geometrical (sweep) or structural bend–twist coupling is applied, this simplification is not valid. The structural mechanical models that are used in the design process have to be validated for their capabilities to predict static and dynamic responses as well as the strength of the structure in all its details
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