Optimal Tower Sizing of the IEA-15MW Offshore Wind Turbine Under Site-Specific Loading

Resumo

This study presents the optimal structural redesign of the IEA-15MW offshore wind turbine tower using a single-objective genetic algorithm coupled with a high-fidelity finite element model implemented in PyMAPDL. The optimization aims to minimize the tower mass while satisfying stress, frequency, displacement, geometric, and buckling constraints under site-specific environmental conditions. Four representative Design Load Cases (DLCs) were considered—normal, extreme, and idling sea states—based on wind and wave spectra typical of Northern Europe. Spectral dynamic responses were computed via power spectral density (PSD) analysis and applied in combination with static wind and wave loading. All optimizations converged to a single robust structural configuration, leading to a 9.94\% mass reduction compared to the IEA-15MW reference design and a reduction in first natural frequency from 0.173 Hz to 0.140 Hz, satisfying the dynamic regime. Post-optimization buckling verification was performed based on Eurocode 3 Part 1--6, confirming shell stability under combined axial and shear stresses. The proposed framework demonstrates the potential of customized GA-based workflows for efficient and constraint-aware offshore tower design.