Fatigue analysis of jacket support structure for offshore wind turbines

In the past few decades and up to now, the fossil energy has exerted tremendous impacts on human environments and gives rise to greenhouse effects while the wind power, especially in offshore region, is an attractive renewable energy resource. For offshore fixed wind turbine, stronger foundation like jacket structure has a good applicability for deeper water depth. Once water depth increases, dynamic responses of offshore wind turbine (OWT) support structures become an important issue. The primary factor will be the total height of support structure increases when wind turbine is installed at offshore locations with deeper water depth, in other words the fatigue life of each components of support structure decrease. The other one will experience more wind forces due to its large blades, apart from wave, current forces, when makes a comparison with offshore oil and gas platforms. Summing up two above reasons, fatigue analysis, in this research, is a crucial aspect for design of offshore wind turbine structures which are subjected to time series wind, wave loads and carried out by aiding of SACS software for model simulation (P-M rules and S-N curves) and Matlab code. Results show that the fatigue life of OWT is decreased accordingly by increasing the wind speed acting on the blades, especially with the simultaneous interaction between wind and wind-induced wave. Hence, this should be considered in wind turbine design. Keywords: offshore wind turbine; Jacket structure; fatigue analysis; P-M rules; S-N curves. Received 01 October 2018, Revised 19 November 2018, Accepted 31 January 2019