Dynamical Analysis And Fatigue Analysis On Tripod Support Structure Of Offshore Wind Turbine Under Wave Loads

China has abundant offshore wind resources, as an emerging renewable energy, it has a vast future. Meanwhile it’s development is facing enormous difficulties, As the foundation of offshore wind turbine suffer kinds of stochastic loads such as waves and currents, so these loads can lead the foundation to fatigue, and the fatigue will seriously affect the security and stability of the wind turbine. In this paper, we focus on the tripod support structure of offshore wind turbine, research the dynamic response analysis and the fatigue analysis under wave load. The primary works in this study are as follows:(1) Based on the finite element method, using ANSYS to establish a numerical model of Tripod Support Structure of Offshore Wind Turbine, in order to improve accuracy, using eight node hexahedron and tetrahedral units to mesh the structure. Through the modal analysis of the structure, we get the natural frequency and the dynamic response characteristics of the structure.(2) Using the JONSWAP spectrum to simulate the irregular wave spectrum, based on linear wave superposition method, we can get time domain irregular wave. Then we can get the displacement and stress dynamic response of the key point through the transient response analysis of the structure under wave force.(3) Based on Morison equation, using spectral analysis method to calculate the hot spot stress of critical area, and get the stresses response spectrum. By comparing these spectrum, we get the frequency range of the strongest structural vibration(4) The effects of wave loads on the fatigue damage of structures are considered by using the fatigue life analysis methods of hot spot stresses based on the S-N curves and the Palmgren-Miner liner fatigue damage cumulative rules. Also, the effects of wave high on fatigue life of structure are discussed. By calculating the fatigue life of the structure, estimate whether it meets the requirements.