ABSTRACT
This chapter discusses a higher-order coupling model is proposed and then incorporated into an in-house program, DARwind, to investigate dynamic stiffening characteristics of the blades and its effects on a spar-type floating offshore wind turbine. It is found that the additional stiffness of slender blades increases with the augment of the rotating speed in the higher-order coupling model. The floating wind turbine is a multi-disciplinary coupling system, and the accurate simulation of rigid-flexible coupling multi-body dynamics is particularly important. A widely accepted view is that neglecting geometric non-linear coupling effects in the conventional hybrid-coordinate dynamical model is the reason for failing to capture the dynamic stiffening phenomenon. The floating frame of reference formulation is one of the most popular kinematic methods to describe the rigid-flexible coupling multi-body system. Since blades of the floating wind turbine are slender and attached to the hub, the blade can be described as an Euler-Bernoulli model of a cantilever beam undergoing large overall motions.
