Ultimate structural and fatigue damage loads of a spar-type floating wind turbine

ABSTRACT

This study addresses the ultimate structural and fatigue damage loads of a spar-type offshore floating wind turbine under joint excitations of wind and wave. Aero-hydro-servo-elastic coupled analysis is performed in time-domain to capture the dynamic responses of the floating wind turbine. Based on the mean up-crossing rate method, the short-term ultimate structural load is estimated. The cumulative fatigue damage load is computed with the S-N method. It is shown that the low-level ultimate load is mostly influenced by wind forces whereas the high-level ultimate load is more closely related to wave forces. The wave excitations dominate the fatigue damage at tower top and tower base, whereas the mooring line fatigue damage is more sensitive to the wind forces.

KEYWORDS:

• Ultimate structural load
• fatigue damage load
• floating wind turbine
• up-crossing rate
• S-N method

ORCID

Liang Li http://orcid.org/0000-0002-8528-3171

Additional information

Funding

This work was supported by China Scholarship Council [grant number 201506230127].