From motion to moments: conditioning analysis of floating offshore wind turbine tower bending

The relationship between measured tower bending moments and motions of the TetraSpar Demonstrator floating offshore wind turbine is assessed using conditioning analysis techniques for an extreme storm event, and indicates that the motion to moment transfer function is linear, but dependent on turbine state and wind speed. Using measured motions and bending moments, a look-up table of linear transfer functions is generated for different turbine speed and wind speed bins. The look-up table is then used to predict tower bending moment from measured motions for a winter period, and the accuracy of the predictions is assessed. Finally, predicted stress from the linear transfer function method is used to calculate fatigue damage, which compares well to fatigue calculated using measured bending moments.