| Offshore wind turbine structures work under the wind and wave loads during service life,which will have an important influence on the dynamic characteristics and fatigue damage characteristics of wind turbine foundation structures. So the dynamic analysis and fatigue analysis carried out on the wind turbine foundation can offer significative information for the wind turbine majorization. In this paper,the dynamic characteristics and fatigue damage characteristics of monopile foundation under the action of wind and wave are analyzed,taking the NREL5 MW monopile wind turbine as the study object. The primary researches are as follows:First,calculate wind loads of different conditions on the offshore wind turbine impeller and tower structure. Simulate fluctuating wind by using the harmonic superposition method,and further calculate the random wind loads on the tower and calculate the random aerodynamic loads on the rotor using blade element momentum theory.Second, calculate wave loads of different working conditions on the pile foundation by the linear wave superposition method and the Morison formula.Third,build supporting structure model of offshore wind turbine in ABAQUS. And proceed the modal analysis based on the model to obtain the natural vibration characteristics of the supporting structure.Load the wind and wave loads calculated earlier on the model and carry out the transient dynamic analysis under different load cases to get response of strategically locations.Fourth, according to the specific structure and environment, choose the appropriate S-N curve,and combining the rain flow counting method with the Miner liner fatigue damage cumulative rules,fatigue damage under wind loads and wave loads is calculated respectively.Finally,calculate the total structure fatigue damage under the combinated wind and wave loads by using different methods and draw a reasonable fatigue life estimation value by comparison and analysis. |
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