ABSTRACT
In this paper, fatigue assessment for the blade root bolts of T-bolt joint of a 5 MW Spar type FOWT is performed where the preload loss is taken into account. During the fatigue assessment, fatigue lives of the blade root bolts with different preload loss ratios are predicted in terms of S-N curves and Palmgren-Miner’s rule to investigate the impact of preload loss ratios on the fatigue lives of blade root bolts. The results show that when preload loss occurs on bolt, fatigue life of the bolt is increased if the bolt joint remains tight. Once the bolt joint is loosened, the fatigue life of the bolt is significantly decreased. The fatigue lives of the bolts around the preload loss bolt are decreased due to preload loss. Moreover, the influence of the quantity and location of preload loss bolts on fatigue life of the blade root bolts is discussed.
