Fatigue assessment of mooring system for floating wind turbines under multi-field coupling effects
To investigate the fatigue issues and influencing factors of the mooring system of a floating wind turbine un-der the coupling effects of multiple environmental conditions,a coupled numerical model for floating wind turbines was es-tablished using the OpenFAST-Sesam-Orcaflex software.Time-domain analysis obtained tension-time histories of the moor-ing lines under different operating conditions.Based on the improved four-point rain-flow counting method and linear cumu-lative damage theory,the T-N curve method was employed to calculate the fatigue damage of the mooring cables under vari-ous short-term sea states and operational conditions.The impact of wind field turbulence intensity on the fatigue damage of the mooring cables was investigated.Results indicate that aerodynamic loads significantly increase the fatigue damage of the mooring cables,emphasizing the importance of considering this load in fatigue assessments.In short-term sea states with wind speeds below the rated wind speed,turbulence intensity is positively correlated with mooring cable fatigue damage,with the maximum influence occurring when the wind speed approaches the rated wind speed.However,when the short-term sea state wind speed exceeds the rated wind speed,the impact of wind field turbulence intensity on mooring fatigue damage is relatively small.The obtained conclusions can serve as a reference for the fatigue assessment of mooring systems in simil-ar platforms.
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