Towards a high-fidelity simulation environment for structural integrity assessment of floating wind energy platforms

Abstract

The present paper presents a preliminary study on the structural integrity analysis of Floating Offshore Wind Turbine (FOWT) platforms, using different methods to compute hydrodynamic loads and determine the deformation and stress levels on the structure via Finite Element Analysis (FEA). Hydrodynamic loads are computed using both a Boundary Element Method (BEM) and a Finite Volume Method considering the Reynolds Average Navier-Stokes (RANS) model. In addition, the structural analysis is divided into two steps, analysing the modal response of the structure on the one hand, and the static structural analysis on the other, where, in turn, two sets of boundary conditions are tested: fixed boundary conditions that totally restrict the motion and spring stiffness boundary conditions that emulate the effect of mooring lines. Overall, the BEM-based is shown to overestimate pressure loads applied on the platform, particularly close to the platform’s natural frequency. Quantitative analysis of the stress and deformation values experienced by the structure is carried out, identifying the critical points of the strucutre. Finally, the setup with fixed boundary conditions in the FEA is shown to unrealistically increase (almost doubling) deformation and stress levels on the structure, suggesting that spring stiffness boundary conditions are more appropriate for floating structures.