Analysis And Optimization Of Pitch Bearing Raceways For Large Wind Turbines

Pitch bearing is the key component of the wind turbine pitch system,and its reliability directly affects the normal operation of the wind turbine.This paper is based on the contact strength analysis theory and the fatigue life theory.Firstly,the finite element model for analyzing the contact load of pitch bearing raceways was established to study the distribution of bearing raceway contact load and the bearing actual contact angle.Secondly,The finite element model for analyzing the stress of pitch bearing raceways was established to study the distribution of contact stress,shear stress and equivalent stress.Finally,the structural parameters of pitch bearing were optimized with the goal of minimizing the maximum contact stress and the longest bearing fatigue life.The research method of the paper provides the basis for the design,verification and optimization of wind turbine pitch bearing,and it has a certain engineering application value.The main research content of the paper includes:(1)The theoretical research on pitch bearings of wind turbines.A numerical model for calculating the contact load of pitch bearing raceways with inner ring fixed and outer ring rotation is established.The calculation method of the maximum contact stress,the maximum shear stress and the maximum equivalent stress of the bearing raceway is given.(2)The study on the finite element modeling technology for analyzing the contact load of pitch bearing raceways of wind turbines.A simplified model for analyzing contact load of pitch bearing raceways was established.The influence of the hub on the contact load analysis of the raceways was discussed.(3)The study on the finite element modeling technology for analyzing the stress of pitch bearing raceways of wind turbines.The finite element model for analyzing the stress of bearing raceways was established.The influence of the relative position of the steel ball and bolt hole and the presence or absence of bolts on the stress analysis of raceways was discussed.A new modeling method for finite element analysis of raceway stress of pitch bearings is presented.(4)The study on the relationship between the structural parameters of pitch bearing and the stress of pitch bearing raceways of wind turbines.The finite element model for analyzing the stress of bearing raceways with different structural parameters was established.The influence of the initial contact angle of bearing,the ditch curvature radius coefficient of raceways,the row distance of raceways,the diameter and the number of steel balls on the maximum contact stress,the maximum shear stress and the maximum equivalent stress of raceways were analyzed.(5)The study on the structural parameters optimization of pitch bearings of wind turbines.The structural parameters of bearing were optimized with the goal of minimizing the maximum contact stress and the longest bearing fatigue life based on the genetic algorithm.