Study On Fatigue Life Influence Factors Of Blade Bearings Used In Wind Turbines

Pitch bearings are core major components of wind turbine.The fatigue life of pitch bearings affects the property and reliability of wind turbine.In order to deeply research the fatigue life of the pitch bearing,according to GL standard,the work analyzes the fatigue life influence factors in detail,based on bearing analysis theory,multi body dynamic modeling theory,finite element method and fatigue theory.The research contents and methods have important practical and theory meaning,and provide a new way for design and fatigue life checking of the pitch system core component.The main research contents of this paper are as follows:(1)Research some relevant theories of pitch bearing fatigue analysis.The theories of load co-simulation model of pitch bearing are analyzed firstly.The correlation between the pitch angles?tip speed ratio and wind-power utilization coefficient is researched while wind turbine pitching.Then the work research the mechanics theory and fatigue theory of pitch bearing modeling,and the static analysis model of pitch bearing is established.(2)The analysis of blade bearing load,based on GL standards and some relevant theories,the load co-simulation model of pitch system core components is established.According to IEC standards,the simulation wind models are built.The load of pitch system core components under the extreme wind and the effects of the load of the pitch bearing under the differences between the pitch angles are analyzed by the load co-simulation model.(3)The blade bearings life is calculated.Based on Herz contact theory,the analysis model of pitch bearings is established by finite element method.According to ISO281,The design formula of bearing life is provided.And compared with the calculation result of theoretical model,the reliability of simplified model is verified through.(4)The fatigue life of the pitch bearing is analyzed.Based on the FE simplified model of pitch bearings built and the formula of bearing life provided,the effects of the hub stiffness,mounting surface flatness and differences between the pitch angles on blade bearing are analyzed.The results show that the hub stiffness,mounting surface flatness and differences between the pitch angles have effects on fatigue life of blade bearings.