Structural strength assessment for thin-walled blade root joint of floating offshore wind turbine (FOWT)

Abstract

A framework is proposed for structural strength assessment for thin-walled blade root joint of floating offshore wind turbine (FOWT). In the framework, loading on the blade root is calculated using a time-domain dynamic analysis where the wind, wave and current as well as gravity and inertial loads are taken into account. Stress responses of the blade root joint are calculated using finite element (FE) method and the interaction effects between each component of blade root joint are considered. Strength analysis for metallic components is based on von Mises criterion and the criterion of maximum principal stress. Failure analysis for the blade root laminate is carried out with the use of Tsai–Hill and Tsai–Wu criteria. A study is further performed to investigate the effects of different design and installation factors on the structural strength of blade root joint. Finally, an engineering application is given to demonstrate the practicability of the framework and the influence of joint form, distance between two rows of the T-bolt, load cases and bolt preload on the structural strength of blade root joint of the FOWT is also discussed.