Study On Load Characteristics And Fatigue Load Of Pitch Bearing Ring

A pitch bearing is an important component of a pitch system that connects the blade and the hub and transfers the load from the blade to the hub.Its structure is large,the overall stiffness is low,and the processing and heat treatment process are complex.Bearing the impact load and the rotation range is generally between 0°~90°,it is particularly necessary to study the load transfer and service life of the variable pitch bearing.At present,scholars have done a general research on variable pitch bearing,and have little consideration for the characteristics of bearing itself and the main failure modes of bearing rings.In view of this situation,an equivalent finite element model of integral structure is established and the accuracy of equivalent model is verified.A rapid determination method based on the contact load distribution characteristics of mechanical model is proposed to determine the position of the plug hole based on the fracture of a bearing ring.In view of the fracture of the bolt hole of the bearing ring,the influence of bolt and load on the bearing is studied and a fast calculation method for the dangerous position of fatigue is proposed based on the Miner damage theory.First,the structural characteristics,working characteristics,material and heat treatment methods of the pitch bearing are briefly analyzed.The equivalent model of the contact between the rolling body and the raceway,the equivalent model of the bolt connection,the establishment of the physical model of the “blade-pitch bearing-hub – spindle”,and the sub-model method are introduced in detail.Aimed at the equivalent model of the contact between the roller and the raceway-“Spring + rigid connection”,the parameter setting in the spring is determined according to the relationship between the contact load and the deformation of Hertz,and the sensitivity analysis of the coupling angle in the equivalent model of the contact between the roller and the raceway is carried out.Secondly,the test rig of pitch bearing and the finite element model of the test rig were est ablished.The contact model of the rolling body and the raceway was equivalent to the "Spring+ rigid connection" method.The experimental results were compared with the results of the fi nite element analysis to verify the accuracy of the load transfer of the rolling body and the rac eway contact model.Then,the structure,geometry and loading characteristics of the bearing are analyzed,the static model of the load distribution of the inner ring is established,and the fast determination method of the plugging hole position is put forward that based on the calculation results of the load distribution.The integral model is analyzed by the FEM.The distribution of contact load is compared with the static results and the sub-model method is used to verify the strength of the location of the recommended plugging hole.Finally,the FEM is used to verify the static strength and static load factor of the bearing under the condition of ultimate load.The relationship between the external load and the stress of the bolt hole in the bearing ring is fitted and the S-N curve of the material is determined according to GL2012,and the cumulative damage is solved by the Miner damage theory.The results show that the accuracy of the equivalent model of "Spring + rigid connection" is verified by experiments.The method of determining the position of plugging hole based on the contact load characteristic of mechanical model is established,and the results of the mechanical model are verified by the FEM.The fatigue life research method of variable pitch bearing based on Miner theory and finite element static strength analysis is completed.It provides a useful reference for the design of pitch bearing.