Stress Analyses of the Offshore Wind Turbine Structures Subjected to Ocean Waves
- Yu-Yun Lin (National Cheng Kung University) | Ssu-Yu Peng (National Cheng Kung University)
- Document ID
- International Society of Offshore and Polar Engineers
- The 27th International Ocean and Polar Engineering Conference, 25-30 June, San Francisco, California, USA
- Publication Date
- Document Type
- Conference Paper
- 2017. International Society of Offshore and Polar Engineers
- Jacket structure, ocean wave, Monopile structure, Finite element analysis
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- 19 since 2007
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Two common offshore wind turbine structures, the monopile type and the jacket type, subjected to ocean wave load were analyzed using finite element simulations. The FEM models were built in ABAQUS, and applied the load combinations consisting of the structural weight, the weight of wind turbine, the wind force, and the ocean wave force. In the analyses, we especially focused on the connection between the tower and the supporting structures, because wind force and ocean wave force may cause the damage to occur at the connections. In the model of the monopile structure, the grout connection to tie the upper steel tower and the lower steel pile is modeled by 3D cohesive elements. In the model of the jacket structure, the connection is a joint welded inclined members to tie the upper tower and the lower sleeves. Ocean wave forces acting on the structures are calculated based on Morison's equation, using the wave velocity and acceleration estimated by linear wave theorem and the site conditions of the wind farm in Taiwan. Both static and dynamic analyses with the distributed ocean wave force were carried out. Its effects on the stresses and deformation of two wind turbine structures were then investigated. We also discussed the possibility of using duplex stainless steel instead of mild carbon steel in the connection part of the jacket structure, because duplex steel has high yielding strength and excellent corrosion resistivity.
Due to growing demands of clean energy, wind energy has become an important source of sustainable energy. Wind turbines have been installed offshore to accommodate even more wind power during the past decade in Europe. The first offshore wind farm in the world is located in Vindeby, Denmark in 1991 and the foundation of wind structures is the gravity base type. Currently, Taiwan Power Company is tentatively scheduling to build the first wind farm in the offshore region of Fangyuan, Changhua, which has the largest wind energy brought by the north-east monsoon in Taiwan.
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