<p style="text-align: justify">Floating offshore wind turbines (FOWTs) in deep water experience cyclic loading from both environment and mechanical operation. For an FOWT, the turbine’s blades are directly subjected to wind loading; and the floater is subjected to wave forces. It has been widely accepted that there is a strong coupling between the floater motions and the turbine forces. As the tower is placed between the upper wind turbine and the floater, the wind and wave loading lead to multi-axial cyclic forces on the tower. The construction of towers makes use of prefabricated sections. These prefabricated sections are bolted together with flanges at either end. The paper aims to investigate the multi-axial stress on FOWT’s towers and analyze its induced fatigue damage at the welding joints around the flanges. A coupled aero-hydro-servo-elastic analysis is conducted to simulate the motion of FOWTs and obtain the time series of multi-axial forces near the flanges. Then, a local welding joint on the flanges is modeled with the multi-axial forces as the boundary conditions to calculate the multi-axial cyclic stress at the hotspots. At last, the fatigue damage at the welding joints is calculated, and the contribution of wind and wave loading to fatigue damage is evaluated. This study can help improve the fatigue design of FOWTs, and evaluate their sensitivity of fatigue damage to wind and wave loadings.</p>

Fatigue Assessment on Reverseâ€“Balanced Flange Connections In Offshore Floating Wind Turbine Towers

Paper Proceedings: https://asmedigitalcollection.asme.org/OMAE/OMAE2021/volume/85116

OMAE 2021

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