外文翻译《轮辐柔性变形效果和滚动接触的潜变力追踪》.docx
《外文翻译《轮辐柔性变形效果和滚动接触的潜变力追踪》.docx》由会员分享,可在线阅读,更多相关《外文翻译《轮辐柔性变形效果和滚动接触的潜变力追踪》.docx(15页珍藏版)》请在冰豆网上搜索。
外文翻译《轮辐柔性变形效果和滚动接触的潜变力追踪》
毕业设计(外文翻译)
题目:
轮辐柔性变形效果和滚动接触的潜变力追踪
学院:
专业名称:
机械设计制造及其自动化
班级学号:
学生姓名:
指导教师:
二O年三月
Effectsofstructureelasticdeformationsofandtrackoncreepforcesofwheel/railinrollingcontact
Effectsofstructureelasticdeformationsofwheelsetandtrackoncreepforcesofwheel/railinrollingcontact
XuesongJin,PingboWu,ZefengWen
NationalTractionPowerLaboratory,SouthwestJiaotongUniversity,Chengdu610031,PRChina
Abstract
Inthispaperthemechanismofeffectsofstructureelasticdeformationsofbodiesinrollingcontactonrollingcontactperformanceisbrieflyanalyzed.Effectsofstructuredeformationsofwheelsetandtrackonthecreepforcesofwheelandrailareinvestigatedindetail.Generalstructureelasticdeformationsofwheelsetandtrackarepreviouslyanalyzedwithfiniteelementmethod,andtherelations,whichexpressthestructureelasticdeformationsandthecorrespondingloadsintherollingdirectionandthelateraldirectionofwheelset,respectively,areobtained.Usingtherelations,wecalculatetheinfluencecoefficientsoftangentcontactofwheelandrail.Theinfluencecoefficientsstandfortheoccurringofthestructureelasticdeformationsduetothetractionofunitdensityonasmallrectangularareainthecontactareaofwheel/rail.TheyareusedtorevisesomeoftheinfluencecoefficientsobtainedwiththeformulaofBossinesqandCerrutiinKalker’stheoryofthree-dimensionalelasticbodiesinrollingcontactwithnon-Hertzianform.Intheanalysisofthecreepforces,themodifiedtheoryofKalkerisemployed.Thenumericalresultsobtainedshowagreatinfluenceexertedbystructureelasticdeformationsofwheelsetandtrackuponthecreepforces.
©2002ElsevierScienceB.V.Allrightsreserved.
Keywords:
Wheel/rail;Rollingcontact;Creepforce;Structureelasticdeformation
1.Introduction
Duringrunningofatrainontrackthefierceactionbetweenwheelsetandrailscauseslargeelasticdeformationsofstructureofwheelsetandtrack.Thelargestructuredeformationsgreatlyaffectperformancesofwheelsandrailsinrollingcontact,suchascreepforces,corrugation[1–3],adhesion,rollingcontactfatigue,noise[4,5]andderailment[6].Sofarrollingcontacttheorieswidelyusedintheanalysisofcreepforcesofwheel/railarebasedonanassumptionofelastichalfspace[7–12].Inotherwords,therelationsbetweentheelasticdeformationsandthetractioninacontactpatchofwheel/railcanbeexpressedwiththeformulaofBossinesqandCerrutiinthetheories.Inpractice,whenawheelsetismovingontrack,theelasticdeformationsinthecontactpatcharelargerthanthosecalculatedwiththepresenttheoriesofrollingcontact.Itisbecausetheflexibilityofwheelset/railismuchlargerthanthatofelastichalfspace.Structureelasticdeformations(SED)ofwheelset/railcausedbythecorrespondingloadsareshowninFigs.1and2.ThebendingdeformationofwheelsetshowninFig.1aismainlycausedbyverticaldynamicloadsofvehicleandwheelset/rail.ThetorsionaldeformationofwheelsetdescribedinFig.1bisproducedduetotheactionoflongitudinalcreepforcesbetweenwheelsandrails.TheobliquebendingdeformationofwheelsetshowninFig.1candtheturnoverdeformationofrailshowninFig.2aremainlycausedbylateraldynamicloadsofvehicleandwheelset/rail.Thetorsionaldeformationswiththesamedirectionofrotationaroundtheaxleofwheelset(seeFig.1d),availableforlocomotive,aremainlycausedbytractiononthecontactpatchofwheel/railanddrivingtorqueofmotor.UptonowveryfewpublishedpapershavediscussionsontheeffectsoftheSEDoncreepagesandcreepforcesbetweenwheelsetandtrackinrollingcontact.
Infact,theSEDofwheelset/railmentionedaboverunslowthenormalandtangentialcontactstiffnessofwheel/rail.Thenormalcontactstiffnessofwheel/railismainlylowedbythesubsidenceoftrack.Thenormalcontactstiffnessloweddoesn’taffectthenormalpressureonthecontactareamuch.Thelowedtangentialcontactstiffnessaffectsthestatusofstick/slipareasandthetractioninthecontactareagreatly.IftheeffectsoftheSEDontherollingcontactaretakenintoaccountinanalysisofrollingcontactofwheel/rail,thetotalslipofapairofcontactingparticlesinacontactareaisdifferentfromthatcalculatedwiththepresentrollingcontacttheories.Thetotalslipofallthecontactingparticlesandthefrictionworkaresmallerthanthoseobtainedunder
conditionthattheSEDisignoredintheanalysisofcreepforcesofwheel/rail.Alsotheratioofstick/slipareasinacontactareaislargerthanthatwithoutconsiderationoftheeffectsoftheSED.
Inthispaperthemechanismofeffectsofstructureelasticdeformationsofbodiesinrollingcontactonrollingcontactperformanceisbrieflyanalyzed,andKalker’stheoreticalmodelofthree-dimensionalelasticbodiesinrollingcontactwithnon-Hertzianformisemployedtoanalyzethecreepforcesbetweenwheelsetandtrack.Inthenumericalanalysistheselectedwheelsetandrailare,respectively,afreight-carwheelsetofconicalprofile,China“TB”,andsteelrailof60kg/m.FiniteelementmethodisusedtodeterminetheSEDofthem.AccordingtotherelationsoftheSEDandthecorrespondingloadsobtainedwithFEM,theinfluencecoefficientsexpressingelasticdisplacementsofthewheelsetandrailproducedbyunitdensitytractionactingonthecontactareaofwheel/railaredetermined.Theinfluencecoefficientsareusedtoreplacesomeoftheinfluencecoeffi-cientscalculatedwiththeformulaofBossinesqandCerrutiinKalker’stheory.TheeffectofthebendingdeformationofwheelsetshowninFig.1aandthecrossedinfluencesamongthestructureelasticdeformationsofwheelsetandrailareneglectedinthestudy.Thenumericalresultsobtainedshowmarkeddifferencesbetweenthecreepforcesofwheelset/railundertwokindsoftheconditionsthateffectsoftheSEDaretakenintoconsiderationandneglected.
2.Mechanismofreducedcontactstiffnessincreasingthestick/slipratioofcontactarea
InordertomakebetterunderstandingofeffectsoftheSEDofwheelset/trackonrollingcontactofwheel/railitisnecessarythatwebrieflyexplainthemechanismofreducedcontactstiffnessincreasingtheratioofstick/slipareainacontactareaundertheconditionofunsaturatedcreep-force.Generallythetotalslipbetweenapairofcontactparticlesinacontactareacontainstherigidslip,thelocalelasticdeformationinacontactareaandtheSED.Fig.3adescribesthestatusofapairofthecontactparticles,A1andA2,ofrollingcontactbodiesandwithoutelasticdeformation.Thelines,A1A_1andA2A_2inFig.3a,aremarkedinordertomakeagoodunderstandingofthedescription.Afterthedeformationsofthebodiestakeplace,thepositionsanddeformationsoflines,A1A_1andA2A_2,areshowninFig.3b.Thedisplacementdifference,w1,betweenthetwodashlinesinFig.3biscausedbytherigidmotionsofthebodiesand(rollingorshift).Thelocalelasticdeformationsofpoints,A1andA2,areindicatedbyu11andu21,whicharedeterminedwithsomeofthepresenttheoriesofrollingcontactbasedontheassumptionofelastic-halfspace,theymakethedifferenceofelasticdisplacementbetweenpointA1andpointA2,u1=u11−u21.Iftheeffectsofstructureelastic
deformationsofbodiesandareneglectedthetotalslipbetweenpoints,A1andA2,canreadas:
S1=w1−u1=w1−(u11−u21)
(1)Thestructureelasticdeformationsofbodiesandaremainlycausedbytraction,pandp_actingonthecontactpatchandtheotherboundaryconditionsofbodiesand,theymakelines,A1A_1andA2A_2generaterigidmotionsindependentofthelocalcoordinates(ox1x3,seeFig.3a)inthecontactarea.Theu10andu20areusedtoexpressthedisplacementsofpointA1andpointA2,respectively,duetothestructureelasticdeformations.Atanyloadingsteptheycanbetreatedasconstantswithrespecttothelocalcoordinatesforprescribedboundaryconditionsandgeometryofbodiesand.ThedisplacementdifferencebetweenpointA1andpointA2,duetou10andu20,shouldbeu0=u10−u20.Soundertheconditionofconsideringthestructuralelasticdeformationsofbodiesand,thetotalslipbetweenpoints,A1andA2,canbewrittenas:
S∗1=w1−u1−u0
(2)ItisobviousthatS1andS∗1aredifferent.Thetraction(orcreep-force)betweenapairofcontactparticlesdependsonS1(orS∗1)greatly.When|S1|>0(or|S∗1|>0)thepairofcontactparticlesisinslipandthetractiongetsintosaturation.Inthesituation,accordingtoCoulomb’sfrictionlawthetractionsoftheabovetwoconditionsaresameifthe
samefrictionalcoefficientsandthenormalpressuresareassumed.Sothecontributionofthetractiontou1isalsosameunderthetwoconditions.If|S1|=|S∗1|>0,|w1|in
(2)hastobelargerthanthatin
(1).Namelythepairsofcontactparticleswithouttheeffectofu0getintotheslipsituationfasterthanthatwiththeeffectofu0.Correspondinglythewholecontactareawithouttheeffectofu0getsintotheslipsituationfastthanthatwiththeeffectofu0.Therefore,theratiosofstick/slipareasandthetotaltractiononcontactareasfortwokindsoftheconditionsdiscussedabovearedifferent,theyaresimplydescribedwithFig.4aandb.Fig.4ashowsthesituationofstick/slipareas.SigninFig.4aindicatesthecasewithoutconsideringtheeffectofu0andindicatesthatwiththeeffectofu0.Fig.4bexpressesarelationshiplawbetweenthetotaltangenttractionF1ofacontactareaandthecreepagew1ofthebodies.SignsandinFi