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Abnormal

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Abnormal

    Abnormal

    ?174?

    CHINESEJOURNAL0FMECHANICALENGINEERING

    Vo1.23,No.2,2010

    DOI:10.3901/CJME.2010.02.174.availableonlineatwww.cjmenet.com;,^n.cjmenet.com.cn

    AbnormalVerticalDynamicPerformanceofSubwayVehicles

    MAWeihua',LUOShihui,andSONGRongrong

    1TractionPowerStateKeyLaboratory,SouthwestJiaotongUniversity,Chengdu610031,China

    2CSRZiyangLocomotiveCo.,Ltd.,Ziyang641301China

    3CollegeofComputerScienceandTechnology,SouthwestUniversityforNationalities,Chengdu610041,China

    ReceivedMarch2,2009;revisedJanuary7,2010;acceptedFebruary24,2010;publishedelectronicallyApril20,2010

    Abstract:Aseriouswheelout.of-roundphenomenonexistsinacertainsubwayvehicleinChina.Moreseriously.theverticalvibration

    ofcarbodyofthissubwayvehiclewillgobeyondtherestrictionofthestandardcriterionwhenthewhee1oubof-roundexceeds0.2mm

    inradiaIdirection.AndthewheeIout-of,roundproblemcouldnotbesolvedbypolishingtheraiIorre-profilingwheels.Aimedatthis

    problem,afurtheranalysisisconductedonthestructureandthesuspensionsystemsofthesubwayvehicle.Itisthoughtthatthe

    additionalstiffnessfunctionofthetractionbar.causedbytheshortlengthandthebiggerconnectionstiffnessofthetractionbar.1eadsto

    theproblemthatthesubwayvehicleissensitivetotheverticalimpact.Bytakingintoaccountthestiffnessofthetractionbar,dynamic

    simulationmodelsofthesubwayvehiclearesetuptostudytheinfluenceoftheadditionalstiffnessfunctionofthetractionbaronthe

    verticaldynamicperformanceofthesubwayvehiclethroughthesimulationmethod.TheresponseofthesubwayvehicletoverticaI

    impactofatrianglepitchisalsosimulated.Simulationresultsindicatethatthecormectionbetweenthecarbodyandthebogiewill

    becomerigidandthedampingfunctionofthesecondarysuspensionwillbedecreasedduetotheadditionalstiffnessofthetractionbar

    inbrakingconditionorrunningoncurvetrack.Thentheverticalresponseofthecarbodytoverticalimpactwillbestrengthenedandthe

    verticalrideindexdecreased.Theverticaldynamicperformanceofthesubwayvehiclewillbeireprovedthroughthemethodof

    decreasingtheconnectionstiffnessofthetractionbar,whichhasbeenvalidatedbythesimulationresults.Thismethodofimprovement

    caneffectivelysolvetheproblemofabnormaldynamicperformanceofthissubwayvehicle,andprovideafoundationforanewtheory

    aboutthetractionbarsystemdesign.

    Keywords:subway,wheelset,tread,outof-round,dynamic

    lIntrOductiOn

    Wheelout.of-roundisacommoncaseofwheelprofile

    deformation.whichexistswidelyinrai1domainbothat

    homeandabroad.Asearlyasinthe1980s.KREUZEN

    describedindetailthephenomenaofpolygonization

    existinginNetherlands.Similarphenomenaalsoarosein

    GermanyandFrancelJ.Inthepastyears,polygonization

    problemwithfewsinusoida1wavesexistedmainlyon

    high.speedtrainsMORYSstudiedthecausesof

    out.of-roundwhee1andprogressivephenomenabvICE

    dynamicmodel,andpointedoutthatathighspeed

    outof-roundwheelleadedtoacutevariationofnorma1 force.

    Noiseandvibrationproducedbyout-of-roundwhee1wil1 disturbpassengers,particularlyatcertainspeed.Meanwhile, out.of-roundwheelincreasesverticalcontactforcebetween Correspondingauthor.E.mail:maweihua2008@gmail.com ThisProjectissupportedbyNationa1NaturalScienceFoundationof China(GrantNo.5077519l1.NationalBasicResearchProgramof China(973Program.GrantNo.2007CB714701.PhDProgramsNew TeacherFoundationofMinistryofEducationofChinarGrantNo. 20090l84120006).theStateKevLaboratoryFreeResearchFundof China(GrantNo.2008TPLT03),andScienceandTechnology DevelopmentFundofSouthwestJiaotongUniversity,China wheelandtrack.whichwill"fatigue"thecomponentsof trackandvehicles,suchaswheelsetbearing,sleeperand track.andthusshortentheirservicelifeJ.Therefore.it's

    veryimportanttostudytherea1causeofout-of-round wheelandfindoutanappropriatesolution.

    UptonoW_theresearchesonthewheelout.of-round problemmainlyfocusedonthesimulationofwheel/rail wearcharacters,whileveryfewquantitativeresearchesto analyzeitsinfluenceonvehicledynamicperformancehave beendone.InRef[7],thecauseofwheelpolygonizationis studied.anditispointedoutthattheexisteneeofimpact loadwilldecreasetheservicelifeofthewhee1.Impact loadscausedbydifferentwheeldefectareresearched throughthemathematicmodelinRef81,whichanalyzes

    thedifierentinfluencesofthehighfrequencyandlow frequencyimpact1oad.andindicatesthattheseimpact 1oadswillbeenlargedwiththeincreaseofthewavelength

    anddepthofthewheeldefect.ThecausesofouVclf-round wheelsaswel1astheirdamagetovehicleandraiJ componentsaredescribedinRef.9].Themathematica1

    modelstopredictthedevelopmentandconsequencesof out.of-roundwheelsaregivenandaseriesofmeasuresto reducethedevelopmentofout-of-roundwheelsare provided.Theproblemonout-clf-roundwheelsintheir CHINESEJOURNALOFMECHANICALENC}INEERING?175? serviceisanalyzedandthewheelou~ofroundnessis categorizedinRef.r10].Anewmathematicalmodelisput forwardnumericallytosimulatethewhee1out-of-round.In thenumericalsimulation.thedynamicmodelofahalf railwayvehiclecoupledwithatangentbackisemployed, inwhichellipticalwheelsareconsideredinthecalculation ofthewheelsandtherailsinrollingcontact.Theeffectof thewhee1out.of-roundonthedynamicbehaviorofthe wheelsetsinthelateraldirectionwasinvestigatedbyusing thenewnumericalmethod.

    0ut.of-roundwheelsexistsnotonlyintraditional railwayvehicles.butalsoinsubwaysvehicles.Some domesticsubwayvehicleshavepresentedseriOUStread damageproblemsinceservicenmning.Statisticallythe averagewearoftreadis1.25mm/10000km.whileusually thisvalueis1.10mm/10000km.Afterashortperiodof running,thissubwayvehiclepresentedspallinginalarge scaleontheintersectionbetweentreadandflange,which leadstothephenomenonofout.of-roundwhee1. Meanwhile,followingthepresentationofouVof-round whee1.verticalvibrationaccelerationofcarbodyis significantandthusseriouslyinfluencesthenormalservice

runningofthesubwayvehicle.

    Aimedatthephenomenonofout-of-roundwheelandthe abnormalverticaldynamicperformanceofthesubway vehicle,thepresentstudy,firstandforemost,attemptsto deducethecausesoftheabove.mentionedabnormal phenomenonthroughtheoryanalysesandthestructure analyses;then,bytakingintoconsiderationthestructure featureoftractionbar,itcomesuDwiththestatementthat theadditionalstiffnessfunctionofthetractionbarhasabig influenceonthevertiealdynamicperformanceofthe subwayvehicle.Thedynamicsimulationmethodis employedtoverifythestatementandcorresponding solutionsareputforwardintheend.

    2ProblemAnalysis

    Thereseemstobearegularpatternfortheout.of roundwheelproblemofthesubwayvehicle.AUnew vehiclesarefacedwithout.of-roundwheelphenomena aftershort.termservicerunning.whichwilloccuragain evenafterpolishingorreprofiling.Whenout-of-round

    wheelexceeds0.2rntninradialdirection.verticaldynamic performanceofthesubwayvehicledegradessignificantly. Investigationindicatesthatthespringoftheprimary suspensionandanti-rollbarjointpresentsomedamage. Thepossiblecausesoftheabovementionedphenomenaare asfollows:

    r11Trackconditionistoobadtorunvehicles;

    (2)Somethingiswrongwiththevehiclebrakingsystem; f31Thedesignofvehicleisdefected.

    Withregardtotheseassumptions.thesubwaycompany performedsometestsrespectively.Toinvestigatethe

impactfromtrack.polishtheackfirstlyanditwasfound

    thatpolishingtrackandre-profilingwheelonlybrought short.termeffect.Soonafter,wheelout-of-round phenomenonaroseagain.Toinvestigatetheimpactfrom trackfurtheLanothervehiclewithsimilarstructurewas introducedtothisline.Therunningresultshowedthatthe wheelwearofthenewlYinoducedsubwayvehiclewas

    notserious.whichprovedobviouslythattrackquality didn'tcausebigproblem.Theinvestigationofvehicle brakingsystemdidn'tshowthatadverseimpactexisted.AU theseresultsindicatethattheproblemexistedinvehicle itselfexceptforthebrakingsystem,andthereforeafurther analysisonthesubwayvehiclestructureisneeded. 3SubwayVehicleStructureAnalyses

    Inrealservice.thewheelofthesubwayvehicleneedsto re.profileaslongastheradialde:formationexceeds O.25mm.whilethestandardis11TUTI.It'Sinevitableto presentellipseonwheelincertainextendduringitsrunning, butit'sabnormalthatwheelout.of-roundwithinstandard valueleadstotoosignificantverticalvibrationofthecar body.

    Smallradialdeformationwillleadtodirectincreaseofthe verticalvibrationofcarbody,andtherelevantrootcause usuallyleadstotheworseningofwheeloutof-round.It

    seemsthatthissubwayvehicledoesn'thavethesecondary suspensionorthesecondarysuspensiondoesn'tfunctionat al1.

    Thebogiestructureofthesubwayvehicleisshownin Fig.1.Theprimarysuspensionconsistsoftapermetal rubberspringwithappropriateverticalandhorizontal

    stiffness.ThesecondarysuspensionismadeuDofair springwithbigflexibility,lateraldamper,verticaldamper andanti.rollbardevice.Obviously,thesubwayvehiclehas goodsuspensionsystemintermsofitsstructure.so dampingfunctionshouldhavebeengood.Thenwhat makesthesecondarysuspensionloseitsdampingfunction? Clearlytheonlysuspectedisthetractionsystem. Fig.1.Bogieofthesubwayvehicle

    ThetractionsystemsketchmapisshowninFig.2.The subwayvehicleadoptsashortsinglepush-pulltractionbar, oneendofwhichisconnectedwithframeandtheotherend ?176?MAWeihua,etal:AbnormalVerticalDynamicPerformanceofSubwayVehicles

    connectedwithcarbody.Bothendsarerubberiointwjth bigstiffness.Theprincipletodesigntractionsystemisto transmittraction/brakingforce.andmeanwhilenotto constrainthemotionofbogieinanydirectionrelativeto carbody.Therefore,shorttractionbarshouldcompensate bogie's1ateraldisplacementrelativetocarbody(oncurve) andverticalbotmcemotion.otherwisetherewil1bean additionalconstraintandthenincreasingthesuspension stiffnessinverticaldirection.whichwillincreasesthe verticalvibrationofthecarbody.Thetractiondeviceofthe subwayvehiclehastwocharacteristics:shorttractionbar and.bigconnectionstifinessfmorethan50MN/m).Soit's quitepossibletointroduceanadditionalconstraint.and thenimpactthesuspensionperformance.

    Tractionbar

    Fig.2.Tractionsystemsketchmap

    AccordingtoRef.[11],ifthereisabigconnection stiffnessofthetractionbar,whenthewhee1setlongitudinal

    vibrationresonanceoccurs.theviolentwheelset longitudinalvibrationresonanceisverylikelytobe transferredtothecarbodvthroughthetractionbar,and thentheabnorma1verticalandlongitudinalvibrationofcar bodywillarise.

    4FunctionofShortTractionBar

    Duetothefactthatthetractionbarisshort.whenthereis abigrelativemotionin1ateralandverticaldirection betweencarbodyandbogie(mainlyhappensoncurve, switch,up/downslopeorrai1ioint,etc),withsame displacement,theswingangleofshorttractionbarisbigger thanthatoflongone.TheprincipleisshowninFig.3. Fig.3.Constrainttovehiclemotionfromtractionbar Whenthereisabigdisplacementdifferenceinverticalor lateraldirectionoftractionbar,sincethetwoconnection pointsonthecarbodycannotmoverelatively,theresultof shorteningtractionbarhastobecompensatedbythe approachofthefrontandrearbogies.Whensubway vehicleisrunningwithconstantspeed.it'seasytorealize thiscompensation.becausetherollingresistanceofwhee1 isverysmal1.Yet.whenvehicleisintraction/braking condition.thewheelsetsisinfactconstrainedbythetrack. andit'shardtochangetherelativepositionofthefrontand rearbogies,orcarbodycan'teasilyhavebounceorlateral motionrelativetobogies.Eventhoughthestiffnessofair springissmall,thiseffectisequivalentwiththatthe longitudinalandverticalstiffnessofsecondarysuspension isbigger.

    Therefore.theresultoftheadditionalstiffnessfromshort tractionbarisequivalenttoanincreaseofthestifinessof

    verticalsupportoftheairspring,whichwillleadtothe followingphenomena.

    (1)Increasedloadofprimarysuspension--thesubway vehicleverticalvibrationisnotdampedsufficientlybyair spring,whichincreasestheloadoftheprimarysuspension, andleadstoitsdamage.

    (2)Increasedloadofthejointofanti.rollbarthe

    instabilityofthelongitudinalpositionbetweenbogieand carbodvresultsinthefactthatapartofverticalforceis transmittedtoantirollbarioint,andtheverticalloadis increasedduringrunning,whichcanbeseeninFig.4.Then theanti.rollbariointdamageiseasilyinduced. NormalconditionAbnorma1condition

    Fig.4.Sketchmapofthepositionofanti?rollbar f31Serioustreadwear--tractionbarsystemresultsin shortconnectioninlongitudina1directionbetweencarbody andbogie,decreasingthelongitudinaldampofcarbody systernandthereismutualjmpactofthelongitudinal vibrationbetweencarbodvandwheelset.Sothewheelset longitudinalvibrationresonancemaybeinducod.which increasesthewearofwheeltreadJ.

    5SimulationofShortTractionBarFunction

    5.1Simulationmodel

    Themodeliscomposedbv1carbody,2bogies.4wheel sets8ioumalboxes,etc.Theprimarysuspensionconsists ofmetalrubberspringwithcone.shaped.Thesecondary suspensioniscomposedbyairspring,lateralandvertical dampers.Constrainedbythevehicleenvelope,the secondarysuspensionairspnngcanonlyhaveverysmall latera1gaD.Inordertopreventtherollingmovementofcar

    body,anti-rol1barandlatera1stopareequipped.Thewheel settreadisGMCtype.matchedwith60kg/msteelrail,and therailcantis1/40.Whenbuildingthemode1.thetraction CHINESEJOURNALOFMECHANICALENGINEERNG?177?

    barisconsideredasanindependentbody,whoselengthis only580mm.Oneendofthetractionbarisconstraintwith thecal"bodNandtheotherendofthetractionbaris connectedwithbogie.

    5.2Verticalfrequencyresponseofcarbody

    Theadditionalstiffnesseffectoftheshorttractionbaris reflectedbytheincreaseofverticalstiffnessofsecondary suspensionairspring.Comparingthecaseofnormal secondarysuspensionstatuewiththecaseofadditional stiffnessofshorttractionbar,thefrequencyresponseresult ofverticalvibrationofcarbodyisshowninFig.5.Itcan beseenthattheresponseofverticalvibrationofcarbodv increasessharplyduetotheadditionalstiffnessefrectof shortactionbar,whichisthemainreasonthatthe

    secondarysuspensionlosetheefficientdampingfunction andtheverticaldynamicperformanceofcarbodV deteriorates.

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    100

    5.3Responseofverticalimpact

    Inordertosimulatethesubwayvehicle'sresponseof verticalimpactundertheefrectofadditionalstiffnessof shorttractionbar,simulationcalculationsagemadeinthe casethatsubwayvehiclerunsoverakindoftrianglepitch duringbrakingcondition.Generallyspeaking,thebraking decelerationofsubwayvehicleisabout0.8-1.0m/s.

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