Research On The Damage Of Single-Column Three-Piles Offshore Wind Turbines Subjected To Ice And Wind Loads

As a non-polluting,resource-rich renewable energy source,offshore wind power has broad development prospects.The support structure of an offshore wind turbine will be directly subjected to wave loads,ice loads and wind loads from the wind turbines.For offshore wind turbines in ice areas,ice loads are the main controlling load and will have a significant impact on the safety and service life of the structure.In addition to this,offshore wind turbines are often susceptible to severe fatigue damage to the support structure when subjected to wind and wave loads and ice loads for long periods of time.Therefore,in this paper,the dynamic response of offshore wind turbines subjected to ice loads and the fatigue damage to the support structure of offshore wind turbines subjected to the combined effects of ice,wind and waves will be investigated using a single column three-pile offshore wind turbine as a model.Firstly,the damage forms of marine ice rafts interacting with different forms of rigid structures are studied and the corresponding ice force curves are calculated to compare and analyse the damage characteristics and ice force values of ice rafts under different damage forms.A numerical model of a single column,three-pile offshore wind turbine support structure is developed to investigate the dynamic response of an ice raft in collision with the support structure of wind turbine.Based on the actual ice conditions,the influence of three factors on the collision of the support structure,namely the thickness of the ice row,the ice row rate and the size of the ice row,is investigated respectively,and the support structure is analysed in terms of unit stress conditions,local deformation and energy absorption.The effect of wave loads on offshore wind turbines subjected to collisions with ice rafts is considered,and a numerical analysis model is developed using the S-ALE based fluid-structure coupling method.The numerical analysis results with and without the flow field are compared and the dynamic response of the offshore wind turbine support structure and the ice rafts in the flow field are investigated separately,and the dynamic response of different ice raft scales in the flow field is studied.The effect of different wave periods and wave heights on the collision of the ice rafts with the support structure is investigated in the light of actual sea conditions.Finally,the fatigue damage of offshore wind turbine support structures under the combined effects of sea ice,wind and wave loads is investigated.The wind speed spectrum was used to simulate the wind speed,calculate the wind load on the wind turbine blade and tower,integrate the effect of wave load and ice load,and calculate the fatigue damage of the offshore wind turbine during the design life by using the time course fatigue analysis method and linear cumulative damage criterion according to the distribution law of each sea ice condition,so as to deduce the fatigue damage of the offshore wind turbine support structure under the combined effect of ice,wind and wave load.The fatigue life of the offshore wind turbine support structure under combined ice,wind and wave loads is thus derived.