Fatigue Performance Of Offshore Wind Turbine Support Structure Under Wave And Wind Loads In Time Domain

The offshore wind resources are abundant and stable.Furthermore,coastal areas where economically developed have suitable conditions to connect with wind power grid.In recent years,there is a trend that the wind farm is developing from land to offshore.It is important for the support structure in fatigue design.In this paper,the fatigue performance of offshore wind turbine support structure under wind and wave loads is studied.And the method of fatigue evaluation in time domain is compared and analyzed.The main contents are as follows,(1)The environment load theory and the calculation software of environmental load,such as Bladed and AQWA,is introduced.Time series of wind load subject to a certain wind spectrum are calculated by Bladed.And time series of wave load subject to a certain wave spectrum are calculated by Aqwa(2)Establish the structure model by using ANSYS,and use pipe node optimization modeling method,This method can not only improve the efficiency of fatigue check,but also improve the calculation accuracy.And also considering the effect of pile-soil nonlinear factor,after the wind load and the wave load was loaded on the structural model,the time history of hot spot stress is calculated under the combined action of wind load and wave load by the transient dynamic analysis,and also calculated the time history of hot spot stress under the wind load and under the wave load.(3)The fatigue damage values of structures under the combined action of wind and wave are calculated by the method of time domain fatigue assessment.Based on the fatigue damage value under the combined action of wind and wave,the accuracy of four kinds of wind and wave damage combination methods are analyzed and compared.The four methods are damage combination method,the root of square root method of damage method,sum of damage method and equivalent stress superposition.