Analysis Of Fatigue Loads And Lifetime Of Wind Turbine Blade Root

The rapid development of economy and technology has accelerated the consumption of traditional fossil energy such as oil and natural gas,and has also accelerated the development of clean energy such as wind energy.By the end of 2017,the total installed capacity of wind power in the world has reached 539.58 GW.In order to improve the utilization efficiency of wind energy and the economics of wind energy development,the length of wind turbine blades is constantly increasing.The blade of the wind turbine is mainly connected to the hub through the blade root,and the blade root root portion is subjected to complex alternating effects such as bending moment,shearing and extrusion during the rotation of the blade,Therefore,the blade root of wind turbine is most prone to fatigue damage.This paper takes the blade root of 2.0MW wind turbine as an example.MATLAB software to achieve the rain flow method of programming,The extreme load history and the fatigue load spectrum of 59 kinds of blades were obtained through the analysis of the rain-flow program.Then using ANSYS15.0 finite element analysis and experimental research method to analyze the fatigue performance of blade roots under various loads.In order to calculate the fatigue life of the bolt,this paper studies the calculation of the bolt load ratio by means of finite element simulation and experiment.By comparing and analyzing the bolt load ratio obtained by the finite element model analysis and the load ratio obtained by the experimental analysis,results show that it is feasible to use the finite element simulation to calculate the bolt load ratio.Based on the experimental research results,this paper uses ANSYS finite element software to establish a 1/182 partial model of blade roots for actual fatigue life analysis.The load ratio of the blade root bolt and the relationship between the stress of the blade root FRP ?UD block and the equivalent axial force were calculated and analyzed by using the finite element software.Based on the bolt load ratio and the relationship between FRP and UD block stress and equivalent axial force,the fatigue stress spectrum of the blade root bolt and the fatigue stress spectrum of the FRP layer and the UD block are obtained based on the equivalent load spectrum.Finally,according to the Miner fatigue linear damage accumulation theory,using the S/N fatigue life curve of the blade root bolt and FRP mentioned in GL2010,the fatigue life calculation of the blade root bolt,glass layup and UD block was carried out.The fatigue damage D of the blade root bolt is calculated to be 0.0172,the maximum damage D of the FRP layer is 9.78E-3,and the maximum damage D of the UD block is 2.96E-3.The calculation results show that the blade root structure design meets the requirements.