Consistency Assurance between Integrated Load Analysis and a Structural Model in Time-domain Analysis for a Floating Offshore Wind Turbine

Abstract

Floating offshore wind substructures operate predominantly under turbine production conditions, where system dynamics are strongly coupled. Accurate structural stress prediction therefore demands time-domain integrated load analysis (ILA). Fatigue governs the design of key components and must be addressed early through a fast, robust workflow from ILA to local stress evaluation. This paper presents a response-based methodology that ensures consistency between environmental loading and structural modeling, rigorously accounting for wind, wave, current, inertia, mooring, and Morison forces. When geometric and dynamic properties are aligned, the resultant boundary forces theoretically converge to zero, validating the integrated approach. This paper presents a validation for load recovery and its influence on the structural response in the time domain. As an application, structural analysis of a conventional semisubmersible FOW (floating offshore wind) platform supporting a 15 MW turbine is performed using both open-source (OpenFAST) and commercial (OrcaFlex) software for integrated load analyses. Recovered wind, wave, and current loads, as well as other resultant forces, are thoroughly analyzed to ensure load balance and verify whether they have been accurately considered in the structural analysis. The present study shows the importance of load balance to ensure the reliability of response-based time-domain structural analysis. This reliability then feeds into the ability to reach substructure design convergence and optimization in an acceptable time, decreasing risk and improving the chances of project success. As part of increasing chances for success, structural fatigue calculations and design can contribute to the fabrication, assembly duration, and costs, especially when considering serial production.

Keywords

Load balance / Floating offshore wind turbine (FOWT) / Response-based time-domain structural analysis / Local structural stresses / Load amplitudes / Load pattern

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Harbin Engineering University and Springer-Verlag GmbH Germany, part of Springer Nature

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