Computer-aided optimization of an offshore jacket for a wind turbine with a simplified load model

Abstract

In this report the jacket structure of a 5MW reference offshore wind turbine has been explored in terms of structural redundancy and for optimisation of the node locations. This has been done by the creation and utilisation of fully parametric scripts that creates input and post processes results from Abaqus CAE. The dynamic nature of offshore wind turbine forms a basis for complex loading of the jacket structure. This makes the analysis work needed to fully understand such structures substantial. Fatigue may be the limiting factor for structure life time, and this has been the evaluating factor for results for both redundancy and optimisation. Five different load cases are employed to evaluate different weather, and give a fuller picture of what the structure may experience. Differences in the evaluated configurations show a nonlinear performance variation in the load cases, which complicates a clear optimal configuration. A further study of the lifetime expected distribution of load cases could be done to better understand this, but only the findings for the individual load cases has been presented in this report. For structural redundancy, the loss of a structural member shows disparity between members in the legs or braces, where the legs shows greater contribution to the stiffness and strength of the tower.