Study on the Application of Duplex Stainless Steel in Offshore Wind Turbine Structures

• Main Authors: Ssu-YuPeng, 彭思瑜
• Other Authors: Yu-Yun Lin
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/w5qja2

碩士 === 國立成功大學 === 土木工程學系 === 104 === SUMMARY Two offshore wind turbine structures, which are the monopile type and the jacket type, subjected to different load combinations were analyzed. The possibility of using duplex stainless steel in the wind turbine structure for its strength and excellent corrosion resistivity was considered. Our analyses were carried out using finite element model in ABAQUS. Load combination consists of the structural weight, the weight of wind turbine, the wind force, and the ocean wave force. The natural vibration frequencies of wind turbine structures and the corresponding deformation modes were also analyzed. The results show that the bending moment and the stress caused by the wind force are much larger than by the ocean wave force. For the monopile structure, the maximum normal stress occurs on the level of seabed and exceeds the yield strength of mild carbon steel, when load combination consists of the structural weight, the weight of wind turbine and the wind force above 2MN. For the jacket structure, the maximum normal stress occurs at the welded joints in the connection part, and causes local buckling when the wind force is above 3MN. The first natural frequency of the monopile structure is higher than that of the jacket structure, and is also higher than the first excitation frequency of the wind turbine rotor. For the jacket structure, the sleeve parts were selected to use duplex stainless steel instead of mild carbon steel, because they are partially immersed in seawater and partially exposed to a seawater splash and their corrosion rate is much higher the other parts. The stresses and the natural vibration frequencies of the jacket structure with duplex stainless steel sleeve are almost the same as those of the jacket structure with mild carbon steel sleeve. It is feasible to apply duplex stainless steel in offshore wind turbine structures, because of its high yielding strength and very low corrosion rate. Key words: Finite element analysis, Monopile structure, Jacket structure, Duplex stainless steel