Study On The Effect Of Structural Elasticity On Load Distribution Of Aeroengine Thin-walled Roller Bearing

Aeronautical bearings are evolving towards thin-walled and components integration.Thin-walled bearings,flexible support bearings will become the main trend in the field of aeroengine bearings and other high-speed equipment.At present,the basic theoretical system of rolling bearings is still the rigid ring hypothesis theory which only considers contact elasticity,and does not consider the elasticity of thin-walled ring structure and its coupling with supporting structure,so it can not meet the needs of the development of rolling bearings.Therefore,taking thin-walled roller bearings of aeroengine as the object,considering the elasticity of thin-walled ring,the coupling effect between housing and ring,and the coupling effect between elastic support structure and thin-walled ring,a quasi-dynamic analysis model is established,the dynamic characteristics of thin-walled roller bearings are analyzed.In order to provide theoretical basis and engineering application value for the development of thin-walled bearing theoretical system,the basic theory of rolling bearing analysis,which is oriented to thin-walled structure and can cover the current traditional structure,has been developed.Firstly,the structural elastic deformation of thin-walled ring roller bearings with single-point constraint is calculated.Based on the pseudo-dynamic method,the dynamic contact effect inside the bearing is analyzed,and the pseudo-dynamic analysis model of thin-walled roller bearings with single-point constraint is established.The analysis results show that the thin-walled ring will undergo significant structural elastic deformation under the action of load,and the internal load distribution state of the bearing will change dramatically.Under single point restraint,the ring will be "flattened",which will lead to more concentrated load distribution in the bearing,the maximum load of the roller/raceway will obviously increase,and the bearing bearing bearing area will obviously change.For thin-walled bearings constrained by rigid housing,the coupling effect between housing and ring is studied.Based on elastic theory,the two-dimensional coordinated surface contact is analyzed.The deformation compatibility equation of thin-walled ring considering the rigid housing is deduced,and the thin-walled roller bearing analysis model considering the assembly relationship between outer ring and housing is established.The influence of housing assembly gap on the deformation of thin-walled outer ring and the variation law of load distribution inside the bearing show that there exists an advantageous interval in the assembly gap.When the outer ring/housing assembly gap is in this interval,the deformation of the ring can optimize the load distribution inside the bearing,reduce the relative sliding of the contact micro-zone inside the bearing,and when the assembly gap is in this interval.When the upper bound of the advantageous interval is larger,the internal load distribution of the bearing is worse.Different material and temperature rise will lead to different expansion of part size,which will also change the assembly gap of outer ring/housing,and then affect the optimization interval.A fatigue life model of thin-walled roller bearings is established.The stress distribution caused by the structural deformation of thin-walled ring in the ring was calculated,and the change of stress state in the secondary surface of the raceway of Thin-walled bearing was analyzed.The analysis results show that when the assembly gap is in a favorable interval,the life of the first correction is prolonged,and the life of the second correction is increased again.When the assembly gap is in favorable interval,the bigger the clearance of bearing,the thinner the wall thickness,the bigger the increase of relative life of bearing.Aiming at the flexible bearing housing with structural elasticity,the finite element model of the squirrel-cage is established,and the structural deformation of the squirrel-cage housing is calculated.Combining with the dynamic model,the coupling of the internal contact elasticity of the bearing,the structural elasticity of the thin-walled ring,the contact of the ring with the housing and the structural elasticity of the housing is studied.The internal contact characteristics of thin-walled squirrel-cage are developed into an analytical model of squirrel-cage integrated bearing.The structural deformation is calculated.The changes of load distribution,bearing stiffness and roller skew are studied.The results show that the squirrel-cage can significantly reduce the overall support stiffness,effectively reduce the maximum contact load inside the bearing,and reduce the slip rate of the bearing.The deformation of squirrel-cage may lead to the inclination of internal rollers of bearings.Therefore,when using squirrel-cage support structure in high-speed shafting,the overall stiffness of support structure and the stability of internal rollers of bearings need to be considered comprehensively.The thin-walled bearing ring deformation test bench is designed.The inner ring is fixed and the flange is loaded at one end.The translation of measuring points on the ring is avoided.The sliding rail restraint and interference assembly are adopted at one end of the flange.The deflection and sliding of the flange are effectively avoided,and the accuracy of measurement results is guaranteed.The squirrel-cage bearing type in practical application is measured and verified.The correctness of the theoretical model in this paper is verified.