| 25 Jun 2026
Fatigue-constrained gradient-based design optimization of main bearing–shaft systems for floating wind turbine drivetrains
Abstract. Floating offshore wind turbines have significant potential for economical and environmentally-efficient solutions for energy production. However, current state-of-the-art witnesses a lack of integrated analysis and optimization of these large, dynamically-coupled complex engineering machines and their critical sub-systems, such as the drivetrain, with research and experience still in their infancy. The aim of the paper is to facilitate efficient and holistic gradient-based multi-disciplinary constraint optimization of drivetrains by exploiting numerical models with varied fidelity-levels. This is illustrated through a constraint optimization of the main-shaft assembly, which includes critical fatigue-limit constraints of main-bearings, bridging design load case-based load spectra reduction with analytically-differentiable damage equivalent loads in contrast to conventional non-smooth bin-counting. The importance of fatigue as a design driver is shown by comparison to only static structural design. The proposed methodology is implemented as a modular extension within the open-source WISDEM-WEIS framework based on OpenMDAO, enabling efficient integration into existing multidisciplinary system-level wind turbine design workflows.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Wind Energy Science.
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