Corrosion Fatigue Life Analysis Of Offshore Wind Turbine Tower

Offshore wind turbine tower, as the important component of the offshore wind turbine, exposed in the complex ocean corrosion environment for long time and worked under a large number of load cycles caused by wind wave and the process of running. So it is very important to analyze the corrosion fatigue life of the offshore wind turbine tower.Choosing the part of the 2.5MW offshore wind turbine tower in the splash zone as the research object. The corrosion fatigue life of the offshore wind turbine tower is analyzed based on the microscopic mechanism of corrosion fatigue. The main contents of this thesis are as follows:(1) According to the pitting accelerated crack initiation mechanism, it is assumed that the pitting corrosion pit looked like half ball and began from a smooth surface, a new method for determining the critical pitting corrosion fatigue crack initiation depth is proposed. A general model for predicting corrosion fatigue crack initiation life is established. The corrosion fatigue crack initiation life of the part of the offshore wind turbine tower is 1.06 years which is in the splash was analyzed by this model.(2) Based on the analysis of corrosion fatigue crack propagation mechanism of the offshore wind turbine tower, the existed model, which recognized the corrosion fatigue as the result of interaction between mechanical and environmental factors which promotes the crack propagation by anodic dissolution at the crack tip and the reduction of free energy at crack surface, is used to analyze the corrosion fatigue crack extension life of the part of the offshore wind turbine tower in the splash area. the corrosion fatigue crack extension life is 26 years.(3) According to the contact sequence between the corrosive environment and the offshore wind turbine tower, the corrosion fatigue life of the offshore wind turbine tower is classified into three parts: protective system failure time, corrosion fatigue crack initiation life and corrosion fatigue extension life. And the corrosion fatigue life is obtained 30.06 years.The work above analyzed the corrosion fatigue life of the offshore wind turbine tower based on the mechanism of corrosion fatigue, which combined the energy change of corrosion fatigue process with electrochemical corrosion theory. A theoretical basis for analyzing the corrosion fatigue life of the offshore wind turbine tower is provided.