航空发动机高速滚动轴承力学特性研究

南京航空航天大学博士学位论文航空发动机高速滚动轴承力学特性研究姓名：唐云冰申请学位级别：博士专业：航空宇航推进理论与工程指导教师：高德平20051101I121l34HertzIIIIIABSTRACTWiththedevelopmentofscienceandtechnology,theperformaceofaero-enginesisimprovedconstantly.Theballbearingiswidelyusedinaero-engines.Itsmechanicalpropertiesexertimportantinfluenceonthedynamiccharacteristicsofrotorsystems,especiallyathighspeed.Sotheresearchonthemechanicalcharacteristicofballbearingsisessentialinordertomeetthedevelopmentofthenewtypeaero-engines.Themaincontentsofthispaperarefollowing.(1)Themechanicalmodelsofballbearingsaresetupbyboththequasi-dynamicmethodandthefiniteelementmethodinthispaper,andthentheloaddistributionofballbearingsisstudied.Therulesofthecontactangle,thedeformation,thestiffnessandthelimitrotationalspeedindifferentstructureparametersandloadparametersareanalyzed.Thecalculationresultsarecomparedwiththeresultsthatobtainedbyexperiment.Itisfoundthatthecalculationresultsareclosetotheexperimentvalues.Thefiniteelementmentodhasadvantagesincalculationalprecision.Ontheotherhand,thequasi-dynamicmethodhasadvantagesincalculationalefficiency.(2)Theminimumoilfilmthicknessandoilfilmstiffnesscharacteristicsofballbearingsarestudiedbytheelastohydrodynamiclubricationtheory.Thesyntheticalstiffnessofballbearingsisobtainedbycombinationthecontactstiffnesswiththeoilfilmstiffness.Theconceptandthecalculationmenthodoftheequivalentstiffnessarepresentedinthispaper.Takingtheceramicballbearingusedinmicroturbineenginesasanexample,anexperimentmethodformeasuringtheequivalentstiffnessandthedampingoftheballbearingsisintroduced.Itisfoundthatwhentheratiooffrequencyislessthan1,theequivalentstiffnesswillbeincreasedwiththerisingoftherotationalspeedinthecertainconditions.(3)Consideringtheeffectofballsandtheradialclearance,theformulathatcalculatesthefatiguelifeofballbearingsismodified.Itisfoundthattheeffectofballscann’tbeignored.Otherwisetheresultwillbeonthehighside.TherulesofIVthefatiguelifeindifferentstructureparametersandloadparametersareanalyzed.Themethodsandthemeasurestoincreasethefatiguelifeofballbearingsareputforward.Askiddingmodelofballbearingsissetup.Therulesoftheskiddingspeedarestudiedbyusingthismodel.Themethodsandthemeasurestoavoidtheskiddingareputforwardinthispaper.(4)Hertzelasticcontacttheoryandbearingkinematicstheoryareappliedtocalculatethenon-linearforcecausedbyballbearings.Avibrationmodelofballbearingsissetup.Thevaryingcompliancevibrationandthevibrationcausedbybearingwavinessesarestudied.Itisfoundthatthevaryingcompliancevibrationisexcitedbythenon-linearbearingforce.Thenon-periodicvibrationcanbeavoidedbyselectingtheproperparameters(speed,damping,radialclearanceandradialforce).Thewavinesswhichiscausedduetothegeometricimperfectionofballbearingsisconsideredasoneoftheimportantvibrationsourcesofbearingsystems.Amodelofballbearing-rotorsystemsisestablishedinthispaper.Thestabilityandthevibrationofbearing-rotorsystemsarestudiedbyusingthismodel.Inconclusion,theloaddistribution,thestiffness,thedamping,thefatiguelife,theskiddingandthevibrationofballbearingsarestudiedinthispaper.Theresultscanprovidethetheoreticaldirectionfordesign,manufacture,usingandmaintenanceofballbearings,whichpossessanimportantthroreticalsignificanceandapplicationvalueinengineering.Keywords:ballbearing,loaddistribution,equivalentstiffness,fatiguelife,skidding,varyingcompliancevibration,surfacewaviness,VIII1.1..................................................................................................92.1................................................................................112.2................................................................................132.3........................................................................152.4()Frd*................................................................................163.1............................................................................203.2................................................................................213.3............................................................................233.4............................................................................233.5............................................................................233.6............................................................................233.7............................................................................243.8............................................................................243.9................................................................253.10...........................................................................................273.11...................................283.12...................................................................303.13.......................................................................................................323.14...................................333.15...................................333.16...........................................343.17................................................................