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Lookup NU author(s): Professor Zhiqiang Hu, Dr Xiangyin Meng
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).
Due to integrated stochastic wind and wave loads, the supporting platform of a floating offshore wind turbine (FOWT) has to bear six degrees of freedom (DOF) motion, which makes the random cyclic loads acting on the structural components, for instance the tower base, more complicated than those on bottom-fixed or land-based wind turbines. These cyclic loads may cause unexpected fatigue damages on a FOWT. This paper presents a study on short-term fatigue damage at the tower base of a 5MW FOWT with a spar-type platform. Fully coupled time-domain simulations code FAST is used and realistic environment conditions are considered to obtain the loads and structural stresses at the tower base. Then the cumulative fatigue damage is calculated based on rainflow counting method and Miner’s rule. Moreover, the effects of the simulation length, the wind-wave misalignment, the wind-only condition and the wave-only condition on the fatigue damage are investigated. It is found that the wind and wave induced loads affect the tower base’s axial stress separately and in a decoupled way, and the wave-induced fatigue damage is greater than that induced by the wind loads. Under the environment conditions with rated wind speed, the tower base experiences the highest fatigue damage when the joint probability of the wind and wave is included in the calculation. Moreover, it is also found that one hour simulation length is sufficient to give an appropriate fatigue damage estimated life for FOWT.
Author(s): Li H, Hu Z, Wang J, Meng X
Publication type: Article
Publication status: Published
Journal: International Journal of Naval Architecture and Ocean Engineering
Year: 2018
Volume: 10
Issue: 1
Pages: 9-20
Print publication date: 01/01/2018
Online publication date: 12/06/2017
Acceptance date: 09/05/2017
Date deposited: 20/06/2017
ISSN (print): 2092-6782
ISSN (electronic): 2092-6790
Publisher: Society of Naval Architects of Korea
URL: https://doi.org/10.1016/j.ijnaoe.2017.05.003
DOI: 10.1016/j.ijnaoe.2017.05.003
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