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Creators/Authors contains: "Schafer, Benjamin W."

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  1. Free, publicly-accessible full text available July 1, 2024
  2. Abstract

    This paper provides an efficient and robust numerical solution for the linear buckling analysis of tubular members, such as the supporting tower structures of wind turbines. The method uses Fourier‐series approximations for the displacement functions. Longitudinal discretization can optionally be applied, i.e., the member can be divided into segments. The strain‐displacement relationship directly considers the curved geometry. The implementation allows for arbitrary support conditions. Four pure loading situations are considered, uniform – in each segment – along the length: normal force, bending moment, torque, and shear force; however, they can arbitrarily be combined, as is commonly occurring in wind turbine towers. The applied methodology results in a computational advantage compared to the shell finite element method, while still maintaining much more generality and applicability compared with common analytical solutions. Furthermore, the method is supplemented with features, as spectral analysis and buckling length calculation.

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  3. Abstract

    Wind turbine towers are highly slender and made of thin cylindrical shells with large diameter‐to‐thickness ratios, which means stability is an essential concern. The high diameter‐to‐thickness ratios of these cylinders make them highly imperfection sensitive, meaning their failure loads and failure modes are highly dependent on initial geometries. Combined bending and torsion is commonly a controlling load case in the upper tower segments, but this load case has not seen significant study to date. To address the knowledge gap, an experimental study was conducted on the stability of cylinders under combined bending and torsion. A total of 48 cylinders were tested with varying diameter‐to‐thickness ratios and bending‐to‐torsion combinations seen in wind turbine towers. To better understand how imperfections affect the buckling modes of these thin‐walled cylinders, a 3D laser scanner was used to determine geometric imperfections of each test specimen prior to testing. This paper details the test setup and results of the experiments.

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