Finite element modeling of a 40m space frame wind turbine tower

Abstract

The “20% Wind Energy by 2030” initiative by the U.S. Department of Energy initiated the investigation of taller wind turbines. The highway infrastructure in the U.S. is causing the wind energy industry to investigate alternative designs; the lattice tower design is one such solution. One company designed a lattice tower that utilizes interference between the bolt and the clamped components. To study the dynamics of this tower an intensive model was created using beam, shell, and solid finite elements. Due to experimental results the model was originally modeled using a fixed boundary; however, the resulting frequencies for the first two modes were high. To investigate if the boundary was the cause of this error, the soil surrounding the tower was modeled using a relatively large linear solid continuum. The addition of the solid continuum greatly improved the results; resulting in a maximum difference of −7% and mode shapes for the experiment and model follow the same trend.