Numerical simulation of fatigue damage in offshore wind turbines under wind-ice coupling effects in brash ice regions

Numerical simulation of fatigue damage in offshore wind turbines under wind-ice coupling effects in brash ice regions

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Fatigue failure is a critical concern for offshore wind turbines (OWTs).In cold-region seas, the presence of sea ice necesitates the consideration of ice loads in the design of OWTs.This study focuses on the NREL 5MW monopile wind turbine and proposes a numerical analysis framework for asesing fatigue damage under wind-ice coupling effects.Aerodynamic loads are calculated using the blade element momentum theory (BEMT).

A numerical brash ice tank is developed by integrating the discrete element (DE) model with Eulerian multiphase flow to simulate the interaction forces between the turbine and the brash ice.Finite element analysis (FEA) is used to calculate the stres time history of structural hotspots under wind-ice coupling effects.Fatigue damage mz7lh3t8hmlt of these hotspots is then determined using the Palmgren-Miner linear damage theory and low-temperature indefinitely baby opi S-N curves.The results indicate a positive correlation between wind speed and structural fatigue damage.

This effect is most pronounced at intermediate wind speeds, while little change in fatigue damage occurs near the cut-in and cut-out wind speeds.The sensitivity of fatigue damage to ice drift speed is influenced by ice concentration.A 20 % increase in ice concentration results in approximately a 98 % increase in the sensitivity of fatigue damage to ice drift speed.Wind and ice loads are not independent of each other, the coupling between wind and ice loads further amplifies fatigue damage by approximately 36.

6 % compared to the sum of individual load effects.This study can provide a reference for fatigue asesment of wind turbines in cold regions.