Accurate structural reliability assessment of floating wind turbine (FWT) systems is a desideratum for achieving consistent optimal reliability levels and cost-effective design. Such reliability assessment should consider relevant system uncertainties-a nontrivial task. Formulation of the reliability problem requires structural demand in form of load and load effect. Support structure loads are predicted with time-domain dynamic simulations. This represents a challenge when thousands of such simulations are required to capture the uncertainty associated with design variables. Finite element analysis (FEA) is commonly used to evaluate load effects such as stresses, strains etc. This can be computationally expensive if not prohibitive when such evaluation is carried out for every time step. To tackle these issues, a framework for expeditious load effect computation and robust reliability analysis of FWT support structures under ultimate limit state design is presented. The framework employs linear elastic FEA and Kriging surrogate models. The adequacy of Kriging as applied in this study is investigated using high fidelity simulation data. The results highlight the importance of incorporating the Kriging uncertainty in the formulation of the limit state function. With the framework presented, FWT support structures can be designed at consistent reliability levels leading to cost reductions.
Achieving substantial reductions in Levelized Cost of Energy (LCOE) of floating wind turbines (FWTs) requires robust reliability assessment that accounts for inherent design uncertainties. A key aspect of such reliability assessment is the definition of limit states. In this regard, load effects need to be evaluated accurately. This paper presents a computational framework for evaluating load effects on FWT support structures. The computed load effect is subsequently characterized. A high fidelity finite element model of the National Renewable Energy Laboratory (NREL) 5MW reference turbine mounted on the OC3-Hywind spar buoy was developed and validated for this purpose. The loads from fully coupled time domain aero-hydro-servo-elastic simulations are transferred for detailed finite element (FE) load effect computation in Abaqus. Matlab® and Python are used as the computational tools for automating the whole analysis from start to finish. The initial part of this study addresses the amount of run-in-time to be excluded from response statistics. Based on convergence studies carried out, recommendations are made for run-in-time to be excluded from response statistics. The maximum von Mises stress in the tower as a measure of yielding is the load effect investigated in this study.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.