Fatigue Analysis Of Bolt Connection In Large Wind Turbine Pitch Bearing

Pitch bearing bolt of Wind turbines bear long-term dynamic load,result in it is vulnerable to fatigue damage.In order to improve security,to evaluate bolt connection's service life through fatigue analysis is significant.Based on GL guideline and VDI2230 standard,the work chooses MW-level wind turbine pitch bearing bolt connection for research,finishes fatigue analysis of bolt hole and bolt.In the FE modeling,some simplifications are used to deal with limitation of calculation,which is difficult in calculation convergence.The method of fatigue analysis for bolt joint is helpful to future work with theoretical and engineering application value.The main contents of this work are as follow:1.The theory of fatigue analysis and process of load spectrum are studied,and cycle spectrum is obtained through compress process,digital sampling,range filter and rainflow counting,the work to establish pitch bearing spectrum is finished.2.The ball's elastic deformation is simulated by nonlinear spring element using the Hertzian contact analysis theory,established the ball-raceway contact finite element model,calculated contact load by theory force model,Through comparing the result with theoretical method,the validity of FE model is verified.3.The FE modeling of bolt connection is finished by link and beam equivalent method,The accuracy of FE model is verified with VDI2230,through comparing the results with theory result,the consequence is link and beam equivalent method is fast and has good accuracy.4.Load-stress relationship can be calculated in term of above FE models.S-N curve of bolt hole and bolt are obtained based on GL guideline and VDI2330 standard,finally,the fatigue damage is calculated based on above information and Miner theory.