State-of-the-art Gaidai hypersurface reliability assessment for semi-submersible wind turbines, accounting for memory effects

Nowadays renewable, sustainable green energy generation gaining momentum, as environmental concerns, e.g., climate change making fossil fuel usage less attractive. Resultingly, offshore wave and wind power are gaining popularity, steadily replacing hydrocarbon energy sources. Floating offshore wind turbines (FOWT), being pivotal for contemporary offshore green wind energy generation.

Accurate structural lifespan prognostics is necessary for safe and resilient technological design, operational safety and economic viability. Non-stationary, multi-modal dynamic environmental wave-wind loads result in accumulated fatigue damage, as well as excessive structural deformations. Presented case study introduces generic, robust multi-modal structural reliability evaluation methodology, based on accurate numerical modelling of in-situ environmental hydro- and aero-dynamic stressors, acting on operating FOWT. Coupled aero-hydro-servo-elastic nonlinear software package OpenFAST was employed for numerical Monte Carlo Simulations (MCS). Investigated 5 MW FOWT is designed to withstand nonlinear, nonstationary, periodically adverse ambient environmental conditions throughout its complete designed service-life. This case study outlines state-of-the-art multi-modal hypersurface risk evaluation and lifetime assessment methodology.

The primary novelty and practical advantage of the proposed multi-modal Gaidai hypersurface structural risk evaluation approach lie within its robust capacity to evaluate structural damage (hazard/failure) risks for complex dynamic structural systems, with no limitation on the structural Number of Degrees Of Freedom (NDOF), i.e., the number of inter-correlated system dimensions/components.