The Fatigue Analysis Of Offshore Wind Turbine Foundation In Service

Offshore wind turbine foundation structures suffer the complicated marine environment and wind turbines loads, which easily produce stress concentration and fatigue failure in the structure connection positions. Corrosion damage is a common form of ocean engineering which can reduce the mechanical properties of the structure, and fatigue failure is more prone to corrosion condition. Therefore, it is of great significance to calculate the fatigue life of the offshore wind turbine foundation structures in service.The paper is based on the practical engineering, and the research object is to caculate the fatigue damage of the key nodes of the tripod foundation throuth fatigue analysis. The primary works in this study are as follows:Firstly, introduce the basic theories of the thesis involved, including the S-N curve, fatigue cumulative damage theory and wave theory. And then ANSYS OFFSHORE-ASAS soft is introduced which is used to calculate the fatigue damage of offshore wind turbine foundation structures.Secondly, given the information is not shared between wind turbine manufacturers and ocean engineering designers. A simplified fatigue damage analysis method is used, namely wave load and wind load impact on infrastructure fatigue analyzed independently with aerodynamic damping linking to each other. And then overlay the fatigue damage due to wind and wave loads.Thirdly, direct superposition of fatigue damage and the equivalent stress method caused by wave and wind independently are used to calculate the total fatigue damage of the foundation. Then compare the results and recommend the appropriate methods to estimate the three pile jacket structure fatigue damage of the key nodes. Finally, calculate the structure of the design fatigue damage, to assess the foundation structure whether fatigue failure happens in service life.Fourthly, according to the specification and research data at home and abroad, the structure corrosion parameters are defined. Then refering to the principle of uniform corrosion, the three pile jacket structure numerical models at 10 years,20 years and 30 years are created, and the influence on structure design fatigue damage induced by structure corrosion is discussed.