Abstract
This paper investigates the fatigue damage of the gears and bearings in a land-based and a spar-type floating wind turbine. The reference 5 MW NOWITECH gearbox is used on a land-based and a floating spar wind turbine. First, the global analysis is carried out in an aero-hydro-servo-elastic code. Next, the forces, moments and motions from the global analysis are applied to the gearbox modelled in a Multi Body Simulation (MBS) and forces on gears and bearings are obtained. The fatigue damage is then calculated based on the SN-curve approach and Palmgren-Miner linear damage hypothesis in an identical wind condition and compared for both turbines.