机械毕业设计英文外文翻译317轮和轨道的结构弹性变形对滚动接触的轮轨蠕变力的影响.docx

机械毕业设计英文外文翻译317轮和轨道的结构弹性变形对滚动接触的轮轨蠕变力的影响.docx

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机械毕业设计英文外文翻译317轮和轨道的结构弹性变形对滚动接触的轮轨蠕变力的影响

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外文文献翻译原文及其译文

Effectsofstructureelasticdeformationsofwheelsetandtrackoncreepforcesofwheel/railinrollingcontact

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

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.ThetotalslipofallthecontactingparticlesandthefrictionworkaresmallerthanthoseobtainedunderconditionthattheSEDisignoredintheanalysisofcreepforcesofwheel/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’sfrictionlawthetractionsoftheabovetwoconditionsaresameifthesamefrictionalcoefficientsandthenormalpressuresareassumed.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.SignsandinFig.4bhavethesamemeaningasthoseinFig.4a.FromFig.4bitisknownthatthetangenttractionF1reachesitsmaximumF1maxatw1=w_1withoutconsideringtheeffectofu0andF1reachesitsmaximumF1maxatw1=w_1withconsideringtheeffectofu0,andw_1