车辆工程汽车离合器的外文文献翻译.docx

车辆工程汽车离合器的外文文献翻译.docx

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车辆工程汽车离合器的外文文献翻译

湖北文理学院

毕业设计（论文）英文翻译

题目

有限元热分析的陶瓷离合器

专业

车辆工程

班级

Xxx

姓名

Xxxx

学号

2010138xx

指导教师

职称

Xxx副教授

2014年2月25日

Fethermalanalysisofaceramicclutch

1.Introduction

Abrasivedryrunningvehicleclutchesareforceclosurecouplings。

Torqueandspeedtransmissionareensuredbythefrictionalforcegeneratedbetweentwopressedsurfaces.Reasonsfortheapplicationofceramicasafrictionmediumincludegoodheatandwearresistanceproperties，whichprovidetheopportunitytodrivehigherpressures,andalowdensity。

Thus,anincreasingpowerdensityisenabledwithaparallelminimizationofconstructionspace。

MeasurementswithafirstprototypeofaclutchdiskusingceramicfacingswereperformedatKarlsruheUniversityinalaboratoryspecializedinpassengercardrivesystemtesting。

Inthecourseofanalysisthefiniteelement（FE）modelwastobeconstructedwiththeknowledgeofmeasurementdataandmeasurementconditions。

Calculationswereintendedtodeterminethetemperaturedistributionoftheclutchdiskanditsenvironmentateachmomentintimecorrespondingtomeasurements。

Itisessentialtobefamiliarwiththetemperaturerangeinordertoexaminethewearcharacteristicsofthesystem.Thus，importantinformationisderivedfrommeasurementdata。

Incriticalloadcases,thehighestexpectedtemperaturesmustbeforecastinspaceandtimeinordertoprotectmeasuringinstrumentsclosetothelocationofheatgeneration。

Thegoalofthisstudyistoanalyzeandmodifytheclutchsystemtoprovidebetteroperatingconditionsbyimprovingtheheatconductionandconvectionofthesystemortoincreasetheamountoftheenergyconvertedintofrictionalheat。

Furthermore,itisdesiredtofindbetterdesignsolutionsformoreefficientclutchsystems.

CalculationswereperformedbytheCosmosDesignStarsoftware。

Duringmodeldevelopment，greatcarehadtobetakenforpropersimplificationofgeometry,theselectionofelementsizes，andthecorrectadjustmentoftimestepsduetothesubstantialhardwarerequirementsfortransientcalculations。

Changesinthermalparameterssuchasthesurfaceheatconvectioncoefficientandthermalloadhadtobetakenintoconsiderationonanon-goingbasisintermsoftimeandlocation.Thetwosidesoftheanalyzedtestclutchsystemcanonlybemanagedbytwoindependentmodelslinkedbyheatpartition,accordingtothehypothesisthatthecontacttemperaturemustbeidenticalonbothsideswhilethereispropercontactbetweenthemanditsvaluemustbeadjustedbyiteration。

Calculationsrevealedthattheheatpartitionchangedbycycleanditdifferedalongtheinnerandoutercontactrings。

Asaresultofthedifferentcoolingcharacteristicsbetweentheceramicandsteelside,aheatflowislaunchedfromtheceramicsidetothesteelside.Thisheatflowwasalsodeterminedbyiteration，itsvaluealsochangesbycycleanddiffersalongtheinnerandoutercontactrings.

2。

Firstprototypeofaclutchusingengineeringceramicsasfrictionmaterial

Theexaminedclutchdiskwasdevelopedaccordingtothe“specificceramic"productdevelopmentprocessestablishedattheInstituteforProductDevelopment（IPEK）attheUniversityofKarlsruhe.Thisdevelopmentprocessalreadyhasthepossibilityforconnectiontoarealtransmissionshaft;further，ithasacushionspringdeviceforthefacingsallowinggoodstartbehaviour.Abrasiveclutchesmustcomplywiththefollowingbasicrequirements:

●hightorquetransmissionaccordingtohighfrictioncoefficients,

●highcomfort（novibrationsthroughself-inducedchattering），

●homogeneoustemperaturedistribution，

●lowwearcharacteristic。

Acriticalelementoftheswitchistheabrasivedisk.Withregardtothedesignutmostcaremustbetakentoselecttherightmaterial.Ahighandconstantfrictioncoefficient,,wearresistanceandthermalresistancearedesiredcharacteristics.Theclutchdiskhasinsteadofthegenerallyappliedring-shapedabrasiveinlettworowsofSSIC（assintered）ceramicpellets.Thesepelletsareplacedon6separatesegments。

Thesegmentsarefixedtothecentralhubbyrivets.Eachsegmentconsistsof4plates，2workingasfacingspringsand2ascarriers。

3。

Measurements

MeasurementswereperformedatthedepartmentofpowertraindevelopmentoftheInstituteforProductDevelopment（IPEK）attheKarlsruheUniversity（TH）ResearchUniversity，whereacategoryIVcomponenttestrigisusedfortestsofnewfrictionalmaterialsandexaminationsofnewmaterialsinrealclutchdisks。

Realconditionsareappliedbythesimulationofdrivingresistance（e.g.startingintheplane,startingatthehill）.Itisacomponenttestrigleveledonthefourthpositionofthetribologicaltestingenvironment.

Inordertogiveanideaofdimensions：

theequipmentlengthisabout4-5m.Thetwoelectricmotorsandtheaxialforcearecontrolledindependentlybycomputer;therebymanyoperationalstatescanberealized。

Thisenablestheequipmenttocompleteamyriadoftribologicalmeasurementsallwhileproperlymodelingtheoperationofaclutchdiskinapassengercar.ItisalsoequippedwithanautomaticITmeasurementsystem。

Measurablequantitiesincludethefollowing:

●twoheavy—dutyelectricmotors（150KW,BaumullerDS160L—305），

●devicesuitableforexertingaxialforce,

●torquemeter（MannerSensortelemetrieMF100），

●axialforcemeter,

●steeldiskinfriction,

●replaceableheadtoaffixthedevicetobetested，

●temperaturealongtwodifferentradiiat0.4mmbelowtheabrasivesurfaceofthesteeldisk（OmegaHJMTSS—IM100U-150-2000,J—typeiro—constantanthermocouples）,

●revolutionsperminuteforbothsides（PolyteneLSV065）.

Thegreatestchallengeoutoftheseistemperaturemeasurementaswewouldliketoknowthetemperatureoftherevolvingsteeldisk。

Thetwothermoelementsplacedinthesteeldiskforwarddatatothecomputerthroughawirelessbluetoothsystemandareplaced0.4mmbelowtheabrasivesurfaceofthesteeldiskonthetwooppositearcsoftheclutchdisk.

3.2.Measurementprocess

Duetocomponentanalysesandcostreductiononlyonesideoftheclutchdiskismountedwithceramicfacings。

Thus，theclutchdiskanditsfittingwillbereferredtoastheceramicside，andtheabrasivesteeldiskwithitsenvironmentrevolvingtogetherwillbereferredtoasthesteelside.Inthecourseofmeasurements,datawerecollectedatasamplingfrequencyof100and1000HZ。

Measurementswereconductedaccordingtothetimecurves.

Themeasurementstartsbyincreasingtherevolutionsperminuteofthesteelside（thedrivingside）toaspecificvalue（1500rpmhere）.Thentheceramicside（thedrivenside），heldatzerorpm，ispushedtowardsthesteeldiskandtheaxialforceisapplieduntiladesignatedvalueisreached（nominally4200Nhere）。

Uponreachingthedesignatedaxialforcetheceramicsideisreleasedandthetwosidesstarttosynchronize.Afewsecondsaftersynchronization,theaxialloadisdiscontinuedandaftersometimeboththesteelandtheceramicsides—revolvingatthesamespeed—aresloweddown。

Thisisdeemedtobeonemeasurementcycle。

Tencyclesarecompletedinthecourseofasinglemeasurement。

Duringapplicationoftheaxialforcetheceramicsideisheldatzerorpmuntilthedesiredforceisreachedtoensuresynchronizationoccursatnearlythesametimeofeachcycle。

Thisisunfavorablefromtheviewpointofbothmeasurementsandcalculations。

Measurementsareusuallyconductedbychangingonly3parameters:

thespeed，theaxialloadandtheinertia.Thefollowingfiguresareappliedinvariouscombinations:

●speedn：

700，1100and1500（rpm）,

●axialforceF：

4200,6400and8400（N）and

●inertiaI：

1,1。

25and1。

5（kgm2）.

Experimentalmeasurementsarelaunchedwithapprox.10-15minintervals,duringwhichthesystemcoolsdowntoabout30-401C.Thismakescalculationsdifficult，astheexacttemperaturedistributionofthesystemisnotknownatthecommencementofthemeasurement.However,itcanbeassumedthataperiodof10-15minissufficientforanearlyhomogeneoustemperaturedistributiontobeproduced.Theparametersforthefollowingsimulationhavebeenchosenforanintermediatecasewithaspeedn=1500rpm,anaxialforceF=4200NandaninertiaI=1kgm2。

4。

Calculationsofheatgeneration

Themechanicalenergyconsumedduringthefrictionoftwobodiesistransformedintoheat.Thegeneratedheatcanbecalculatedbythefollowingsimpleformula：

Q=μ·ν·F[W］.

wheremisthethefrictionalcoefficient；vistheslidingvelocity；Fistheforceperpendicularlycompressingthesurfaces.Andtheheatfluxdensitypersurfaceunitisq=μ·ν·p[Wm2］。

wherepisthethepressurecalculatedasaratiooftheforceandthecontactingsurface。

Astheceramictabletsareplacedattwodifferentradiialongtheclutchdisk，theheatgeneratedmustbecalculatedseparatelyforeachradii。

Slidingcanbedividedintotwosections。

Inthefirstsection,theceramicsideiskeptinastationarypositionbybraking，meanwhiletheaxialloadisincreased；thereforecompressionchangesinthecourseoftimewhilethespeeddifferencebetweenthetwosidesisconstant。

Inthesecondsection（atsynchronization）thespeeddifferenceisequalizedwhiletheforcevalueisconstant，sovelocitychangesintime.Onthebasisthereof,theheatgeneratedis

.

Thenominalcontactareaistheaggregateofthecontactingsurfacesofthe24and18ceramictabletsonthegivenring.Thediameterofceramictabletsis：

。

Calculationswereperformedfortheloadcasetobecharacterizedbythefollowingparameters:

。

Basedonexperimentalmeasurementsaconstantfrictioncoefficientof0.4wasestablished.

.

Thevelocitycanbecalculat