Analysis Of Dynamic Characteristics And Fatigue Performance Of Wind Turbine Blades

With the rapid development of modern wind power industry and technology,wind turbine blades are showing the development trend of larger size,more flexibility and new shape.In the meanwhile,the structural stability,aeroelasticity and fatigue performance of large blades have gradually attracted extensive attention from scientific researchers.Based on the theoretical and numerical simulation analysis,this paper conducts related research on the critical buckling load,the critical dynamic pressure of flutter and the fatigue performance of wind turbine blades.The main research contents of this paper are as follows:Firstly,the local shear buckling load and axial compression buckling load of wind turbine blades under simply supported and fixed supported boundary conditions are given.Based on the rectangular orthotropic laminated plate model,the buckling load are solved by the variational method and the calculation method of simultaneously solving the shear flow and rotation angle of thin-walled structure.Secondly,by simplifying the wind turbine blade into a two-dimensional plate model,the dynamic equation of blade flutter is established.The critical dynamic pressure and flutter boundary of blade flutter are obtained by trial-and-error solution,while the influence of aerodynamic damping and centrifugal stiffness on flutter are also analyzed.In addition,it is considered that before the overall flutter of the wind turbine blade occurs,the wall flutter may first occur due to local buckling.Through the Galerkin method,the critical dynamic pressures of blade flutter under two boundary conditions of simply supported and fixed supported are obtained.Finally,the load distribution affecting the fatigue life of blades is analyzed based on the strip theory.Through GH Bladed,the steady state operating load of the blade is obtained,and then the equivalent stress value of blade root is determined.According to the Weibull distribution function,combined with the fatigue curve of FRP composite materials,the Palmgren-Miner linear fatigue cumulative damage rule is applied to study the fatigue characteristics of FRP blades.