Strength Analysis And Study On Fatigue Life Of Blade Root Connection Structure Of Large-scale Wind Turbine

With the development of society,people’s demands for ecological environment are getting higher and higher.Therefore,the use of renewable energy and clean energy has attracted the attention of all over the world.As one of the main ways of using new energy,wind power generation has been widely used.Due to the trend of large-scale development of wind turbine,its design requirements are higher,and the requirements of the key parts of the wind turbine are also higher.The bolt connection structure of wind turbine is very important.High strength bolts are used for connecting bolts of wind turbines.High strength bolt,compared to common bolts in the same size,with a large load to bear,better mechanical properties,resistance to fatigue,etc.,was widely used in the wind turbine.In order to ensure the reliable operation of the whole wind turbine,it is necessary to analyze the strength and fatigue life of high strength bolts.Based on the theory of mechanics,reference to standard of VDI2230 high strength bolt system design and Germanischer Lloyd(GL)wind turbine certification standards,combined with the finite element software ANSYS and fatigue analysis software nCode and Miner linear cumulative damage theory,a systematic study of strength of the high strength bolt with blade and root the inner ring of variable pitch bearing connection.The main contents as follows:(1)The design calculation of the high strength bolt with blade and root the inner ring of variable pitch bearing connection of the 2MW wind turbine are analyzed.Considering the eccentric clamping and eccentric loading in the connection,the connection model is simplified,and a local model of single bolt of blade root connection is created.According to the design standard of VDI2230 high strength bolt and the detailed structure size,the calculation and analysis of the blade root bolt are carried out.Mainly include the determination of bolt diameter,nominal tightening coefficient,the minimum clamping force,and flexibility of bolts and connections,and bolt pretightening force,and checking the strength of bolt assembly stress,work stress,alternating stress.(2)Strength analysis of the high strength bolt with blade and root the inner ring of variable pitch bearing connection.The ANSYS software was used to establish the finite element model of the blade root bolt connection of 2MW wind turbine,the blade root bolt in static analysis,including:comparative analysis of stress and strain of bolt between local model and whole model of the blade root connection structure;comparative analysis of the results ofstress and strain of bolts on the 8 typical extreme conditions;comparative analysis of the stress and strain distribution of the dangerous section of bolt group at different bolt positions;check the bolt connection of dangerous bolt.(3)The fatigue life analysis of the high strength bolt with blade and root the inner ring of variable pitch bearing connection.On the basis of static analysis and fatigue cumulative damage theory,the fatigue life analysis and estimation of wind turbine blade root connection bolts are carried out by using nCode fatigue analysis software.