ANSYS130理論參考手冊(cè)

Release13.0-?2010SASIP,Inc.Allrightsreserved.TableofContents1.AnalyzingThermalPhenomena1.1.HowANSYSTreatsThermalModeling.Convection.Radiation.SpecialEffects.Far-FieldElements1.2.TypesofThermalAnalysis1.3.Coupled-FieldAnalyses1.4.AboutGUIPathsandCommandSyntax2.Steady-StateThermalAnalysis2.1.AvailableElementsforThermalAnalysis2.2.CommandsUsedinThermalAnalyses2.3.TasksinaThermalAnalysis2.4.BuildingtheModel.UsingtheSurfaceEffectElements.CreatingModelGeometry2.5.ApplyingLoadsandObtainingtheSolution.DefiningtheAnalysisType.ApplyingLoads.UsingTableandFunctionBoundaryConditions.SpecifyingLoadStepOptions.GeneralOptions.NonlinearOptions.OutputControls.DefiningAnalysisOptions.SavingtheModel.SolvingtheModel2.6.ReviewingAnalysisResults.Primarydata.Deriveddata.ReadingInResults.ReviewingResults2.7.ExampleofaSteady-StateThermalAnalysis(CommandorBatchMethod).TheExampleDescribed.TheAnalysisApproach.CommandsforBuildingandSolvingtheModel2.8.PerformingaSteady-StateThermalAnalysis(GUIMethod)2.9.PerformingaThermalAnalysisUsingTabularBoundaryConditions.RunningtheSampleProblemviaCommands.RunningtheSampleProblemInteractively2.10.WheretoFindOtherExamplesofThermalAnalysis3.TransientThermalAnalysis3.1.ElementsandCommandsUsedinTransientThermalAnalysis3.2.TasksinaTransientThermalAnalysis3.3.BuildingtheModel3.4.ApplyingLoadsandObtainingaSolution.DefiningtheAnalysisType.EstablishingInitialConditionsforYourAnalysis.SpecifyingLoadStepOptions.NonlinearOptions.OutputControls3.5.SavingtheModel.SolvingtheModel3.6.ReviewingAnalysisResults.HowtoReviewResults.ReviewingResultswiththeGeneralPostprocessor.ReviewingResultswiththeTimeHistoryPostprocessor3.7.ReviewingResultsasGraphicsorTables.ReviewingContourDisplays.ReviewingVectorDisplays.ReviewingTableListings3.8.PhaseChange3.9.ExampleofaTransientThermalAnalysis.TheExampleDescribed.ExampleMaterialPropertyValues.ExampleofaTransientThermalAnalysis(GUIMethod).CommandsforBuildingandSolvingtheModel3.10.WheretoFindOtherExamplesofTransientThermalAnalysis4.Radiation4.1.AnalyzingRadiationProblems4.2.Definitions4.3.UsingLINK31,theRadiationLinkElement4.4.ModelingRadiationBetweenaSurfaceandaPoint4.5.UsingtheAUX12RadiationMatrixMethod.Procedure.RecommendationsforUsingSpaceNodes.GeneralGuidelinesfortheAUX12RadiationMatrixMethod4.6.UsingtheRadiositySolverMethod.Procedure.FurtherOptionsforStaticAnalysis4.7.AdvancedRadiosityOptions4.8.Exampleofa2-DRadiationAnalysisUsingtheRadiosityMethod(CommandMethod).TheExampleDescribed.CommandsforBuildingandSolvingtheModel4.9.Exampleofa2-DRadiationAnalysisUsingtheRadiosityMethodwithDecimationandSymmetry(CommandMethod).TheExampleDescribed.CommandsforBuildingandSolvingtheModelRelease13.0-?2010SASIP,Inc.Allrightsreserved.Chapter

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AnalyzingThermalPhenomenaAthermalanalysiscalculatesthetemperaturedistributionandrelatedthermalquantitiesinasystemorcomponent.Typicalthermalquantitiesofinterestare:ThetemperaturedistributionsTheamountofheatlostorgainedThermalgradientsThermalfluxes.Thermalsimulationsplayanimportantroleinthedesignofmanyengineeringapplications,includinginternalcombustionengines,turbines,heatexchangers,pipingsystems,andelectroniccomponents.Inmanycases,engineersfollowathermalanalysiswithastressanalysistocalculatethermalstresses(thatis,stressescausedbythermalexpansionsorcontractions).Thefollowingthermalanalysistopicsareavailable:HowANSYSTreatsThermalModelingTypesofThermalAnalysisCoupled-FieldAnalysesAboutGUIPathsandCommandSyntax1.1.

HowANSYSTreatsThermalModelingOnlytheANSYSMultiphysics,ANSYSMechanical,ANSYSProfessional,andANSYSFLOTRANprogramssupportthermalanalyses.ThebasisforthermalanalysisinANSYSisaheatbalanceequationobtainedfromtheprincipleofconservationofenergy.(Fordetails,consulttheTheoryReferencefortheMechanicalAPDLandMechanicalApplications.)ThefiniteelementsolutionyouperformviaANSYScalculatesnodaltemperatures,thenusesthenodaltemperaturestoobtainotherthermalquantities.TheANSYSprogramhandlesallthreeprimarymodesofheattransfer:conduction,convection,andradiation..

ConvectionYouspecifyconvectionasasurfaceloadonconductingsolidelementsorshellelements.Youspecifytheconvectionfilmcoefficientandthebulkfluidtemperatureatasurface;ANSYSthencalculatestheappropriateheattransferacrossthatsurface.Ifthefilmcoefficientdependsupontemperature,youspecifyatableoftemperaturesalongwiththecorrespondingvaluesoffilmcoefficientateachtemperature.Foruseinfiniteelementmodelswithconductingbarelements(whichdonotallowaconvectionsurfaceload),orincaseswherethebulkfluidtemperatureisnotknowninadvance,ANSYSoffersaconvectionelementnamedLINK34.Inaddition,youcanusetheFLOTRANCFDelementstosimulatedetailsoftheconvectionprocess,suchasfluidvelocities,localvaluesoffilmcoefficientandheatflux,andtemperaturedistributionsinbothfluidandsolidregions..

RadiationANSYScansolveradiationproblems,whicharenonlinear,infourways:Byusingtheradiationlinkelement,LINK31Byusingsurfaceeffectelementswiththeradiationoption(SURF151in2-DmodelingorSURF152in3-Dmodeling)BygeneratingaradiationmatrixinAUX12andusingitasasuperelementinathermalanalysis.ByusingtheRadiositySolvermethod.Fordetailedinformationonthesemethods,seeRadiation..

SpecialEffectsInadditiontothethreemodesofheattransfer,youcanaccountforspecialeffectssuchaschangeofphase(meltingorfreezing)andinternalheatgeneration(duetoJouleheating,forexample).Forinstance,youcanusethethermalmasselementMASS71tospecifytemperature-dependentheatgenerationrates..

Far-FieldElementsFar-fieldelementsallowyoutomodeltheeffectsoffar-fielddecaywithouthavingtospecifyassumedboundaryconditionsattheexteriorofthemodel.Asinglelayerofelementsisusedtorepresentanexteriorsub-domainofsemi-infiniteextent.Formoreinformation,seeFar-FieldElementsintheLow-FrequencyElectromagneticAnalysisGuide.1.2.

TypesofThermalAnalysisANSYSsupportstwotypesofthermalanalysis:Asteady-statethermalanalysisdeterminesthetemperaturedistributionandotherthermalquantitiesundersteady-stateloadingconditions.Asteady-stateloadingconditionisasituationwhereheatstorageeffectsvaryingoveraperiodoftimecanbeignored.Atransientthermalanalysisdeterminesthetemperaturedistributionandotherthermalquantitiesunderconditionsthatvaryoveraperiodoftime.1.3.

Coupled-FieldAnalysesSometypesofcoupled-fieldanalyses,suchasthermal-structuralandmagnetic-thermalanalyses,canrepresentthermaleffectscoupledwithotherphenomena.Acoupled-fieldanalysiscanusematrix-coupledANSYSelements,orsequentialload-vectorcouplingbetweenseparatesimulationsofeachphenomenon.Formoreinformationoncoupled-fieldanalysis,seetheCoupled-FieldAnalysisGuide.1.4.

AboutGUIPathsandCommandSyntaxThroughoutthisdocument,youwillseereferencestoANSYScommandsandtheirequivalentGUIpaths.Suchreferencesuseonlythecommandname,becauseyoudonotalwaysneedtospecifyallofacommand'sarguments,andspecificcombinationsofcommandargumentsperformdifferentfunctions.ForcompletesyntaxdescriptionsofANSYScommands,consulttheCommandReference.TheGUIpathsshownareascompleteaspossible.Inmanycases,choosingtheGUIpathasshownwillperformthefunctionyouwant.Inothercases,choosingtheGUIpathgiveninthisdocumenttakesyoutoamenuordialogbox;fromthere,youmustchooseadditionaloptionsthatareappropriateforthespecifictaskbeingperformed.Foralltypesofanalysesdescribedinthisguide,specifythematerialyouwillbesimulatingusinganintuitivematerialmodelinterface.Thisinterfaceusesahierarchicaltreestructureofmaterialcategories,whichisintendedtoassistyouinchoosingtheappropriatemodelforyouranalysis.SeeMaterialModelInterfaceintheBasicAnalysisGuidefordetailsonthematerialmodelinterface.Release13.0-?2010SASIP,Inc.Allrightsreserved.Chapter

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Steady-StateThermalAnalysisTheANSYSMultiphysics,ANSYSMechanical,ANSYSFLOTRAN,andANSYSProfessionalproductssupportsteady-statethermalanalysis.Asteady-statethermalanalysiscalculatestheeffectsofsteadythermalloadsonasystemorcomponent.Engineer/analystsoftenperformasteady-stateanalysisbeforeperformingatransientthermalanalysis,tohelpestablishinitialconditions.Asteady-stateanalysisalsocanbethelaststepofatransientthermalanalysis,performedafteralltransienteffectshavediminished.Youcanusesteady-statethermalanalysistodeterminetemperatures,thermalgradients,heatflowrates,andheatfluxesinanobjectthatarecausedbythermalloadsthatdonotvaryovertime.Suchloadsincludethefollowing:ConvectionsRadiationHeatflowratesHeatfluxes(heatflowperunitarea)Heatgenerationrates(heatflowperunitvolume)ConstanttemperatureboundariesAsteady-statethermalanalysismaybeeitherlinear,withconstantmaterialproperties;ornonlinear,withmaterialpropertiesthatdependontemperature.Thethermalpropertiesofmostmaterialdovarywithtemperature,sotheanalysisusuallyisnonlinear.Includingradiationeffectsalsomakestheanalysisnonlinear.Thefollowingsteady-statethermalanalysistopicsareavailable:AvailableElementsforThermalAnalysisCommandsUsedinThermalAnalysesTasksinaThermalAnalysisBuildingtheModelApplyingLoadsandObtainingtheSolutionReviewingAnalysisResultsExampleofaSteady-StateThermalAnalysis(CommandorBatchMethod)PerformingaSteady-StateThermalAnalysis(GUIMethod)PerformingaThermalAnalysisUsingTabularBoundaryConditionsWheretoFindOtherExamplesofThermalAnalysis2.1.

AvailableElementsforThermalAnalysisTheANSYSandANSYSProfessionalprogramsincludeabout40elements(describedbelow)tohelpyouperformsteady-statethermalanalyses.Fordetailedinformationabouttheelements,seetheElementReference,whichmanualorganizeselementdescriptionsinnumericorder.Elementnamesareshowninuppercase.Allelementsapplytobothsteady-stateandtransientthermalanalyses.SOLID70alsocancompensateformasstransportheatflowfromaconstantvelocityfield.Table

2.1

2-DSolidElementsElementDimens.ShapeorCharacteristicDOFsPLANE352-DTriangle,6-nodeTemperature(ateachnode)PLANE552-DQuadrilateral,4-nodeTemperature(ateachnode)PLANE752-DHarmonic,4-nodeTemperature(ateachnode)PLANE772-DQuadrilateral,8-nodeTemperature(ateachnode)PLANE782-DHarmonic,8-nodeTemperature(ateachnode)Table

2.2

3-DSolidElementsElementDimens.ShapeorCharacteristicDOFsSOLID703-DBrick,8-nodeTemperature(ateachnode)SOLID873-DTetrahedron,10-nodeTemperature(ateachnode)SOLID903-DBrick,20-nodeTemperature(ateachnode)SOLID2783-DBrick,8-nodeTemperature(ateachnode)SOLID2793-DBrick,20-nodeTemperature(ateachnode)Table

2.3

RadiationLinkElementsElementDimens.ShapeorCharacteristicDOFsLINK312-Dor3-DLine,2-nodeTemperature(ateachnode)Table

2.4

ConductingBarElementsElementDimens.ShapeorCharacteristicDOFsLINK333-DLine,2-nodeTemperature(ateachnode)Table

2.5

ConvectionLinkElementsElementDimens.ShapeorCharacteristicDOFsLINK343-DLine,2-nodeTemperature(ateachnode)Table

2.6

ShellElementsElementDimens.ShapeorCharacteristicDOFsSHELL1313-DQuadrilateral,4-nodeMultipletemperatures(ateachnode)SHELL1323-DQuadrilateral,8-nodeMultipletemperatures(ateachnode)Table

2.7

Coupled-FieldElementsElementDimens.ShapeorCharacteristicDOFsPLANE132-DThermal-structural,4-nodeTemperature,structuraldisplacement,electricpotential,magneticvectorpotentialFLUID1163-DThermal-fluid,2-nodeor4-nodeTemperature,pressureSOLID53-DThermal-structuralandthermal-electric,8-nodeTemperature,structuraldisplacement,electricpotential,andmagneticscalarpotentialSOLID983-DThermal-structuralandthermal-electric,10-nodeTemperature,structuraldisplacement,electricpotential,magneticvectorpotentialLINK683-DThermal-electric,2-nodeTemperature,electricpotentialSHELL1573-DThermal-electric,4-nodeTemperature,electricpotentialTARGE1692-DTargetsegmentelementTemperature,structuraldisplacement,electricpotentialTARGE1703-DTargetsegmentelementTemperature,structuraldisplacement,electricpotentialCONTA1712-DSurface-to-surfacecontactelement,2-nodeTemperature,structuraldisplacement,electricpotentialCONTA1722-DSurface-to-surfacecontactelement,3-nodeTemperature,structuraldisplacement,electricpotentialCONTA1733-DSurface-to-surfacecontactelement,4-nodeTemperature,structuraldisplacement,electricpotentialCONTA1743-DSurface-to-surfacecontactelement,8-nodeTemperature,structuraldisplacement,electricpotentialCONTA1752-D/3-DNode-to-surfacecontactelement,1nodeTemperature,structuraldisplacement,electricpotentialPLANE2232-DThermal-structural,thermal-electric,structural-thermoelectric,andthermal-piezoelectric,8-nodeTemperature,structuraldisplacement,electricpotentialSOLID2263-DThermal-structural,thermal-electric,structural-thermoelectric,andthermal-piezoelectric,20-nodeTemperature,structuraldisplacement,electricpotentialSOLID2273-DThermal-structural,thermal-electric,structural-thermoelectric,andthermal-piezoelectric,10-nodeTemperature,structuraldisplacement,electricpotentialTable

2.8

SpecialtyElementsElementDimens.ShapeorCharacteristicDOFsMASS711-D,2-D,or3-DMass,one-nodeTemperatureCOMBIN371-DControlelement,4-nodeTemperature,structuraldisplacement,rotation,pressureSURF1512-DSurfaceeffectelement,2-nodeto4-nodeTemperatureSURF1523-DSurfaceeffectelement,4-nodeto9-nodeTemperatureMATRIX50[1]Matrixorradiationmatrixelement,nofixedgeometry[1]INFIN9[2]2-DInfiniteboundary,2-nodeTemperature,magneticvectorpotentialINFIN47[2]3-DInfiniteboundary,4-nodeTemperature,magneticvectorpotentialINFIN110[2]2-DInfiniteboundary,4or8nodesTemperature,magneticvectorpotential,electricpotentialINFIN111[2]3-DInfiniteboundary,8or20nodesTemperature,magneticscalarpotential,magneticvectorpotential,electricpotentialCOMBIN141-D,2-D,or3-DCombinationelement,2-nodeTemperature,structuraldisplacement,rotation,pressureCOMBIN391-DCombinationelement,2-nodeTemperature,structuraldisplacement,rotation,pressureCOMBIN401-DCombinationelement,2-nodeTemperature,structuraldisplacement,rotation,pressureAsdeterminedfromtheelementtypesincludedinthissuperelement.Forinformationonmodelingtheeffectsoffar-fielddecay,seeFar-FieldElementsintheLow-FrequencyElectromagneticAnalysisGuide.2.2.

CommandsUsedinThermalAnalysesExampleofaSteady-StateThermalAnalysis(CommandorBatchMethod)andPerformingaSteady-StateThermalAnalysis(GUIMethod)showyouhowtoperformanexamplesteady-statethermalanalysisviacommandandviaGUI,respectively.Fordetailed,alphabetizeddescriptionsoftheANSYScommands,seetheCommandReference.2.3.

TasksinaThermalAnalysisTheprocedureforperformingathermalanalysisinvolvesthreemaintasks:Buildthemodel.Applyloadsandobtainthesolution.Reviewtheresults.Thenextfewtopicsdiscusswhatyoumustdotoperformthesesteps.First,thetextpresentsageneraldescriptionofthetasksrequiredtocompleteeachstep.Anexamplefollows,basedonanactualsteady-statethermalanalysisofapipejunction.TheexamplewalksyouthroughdoingtheanalysisbychoosingitemsfromANSYSGUImenus,thenshowsyouhowtoperformthesameanalysisusingANSYScommands.2.4.

BuildingtheModelTobuildthemodel,youspecifythejobnameandatitleforyouranalysis.Then,youusetheANSYSpreprocessor(PREP7)todefinetheelementtypes,elementrealconstants,materialproperties,andthemodelgeometry.(Thesetasksarecommontomostanalyses.TheModelingandMeshingGuideexplainsthemindetail.)Forathermalanalysis,youalsoneedtokeepthesepointsinmind:Tospecifyelementtypes,youuseeitherofthefollowing:Command(s):ETGUI:Main

Menu>Preprocessor>ElementType>Add/Edit/DeleteTodefineconstantmaterialproperties,useeitherofthefollowing:Command(s):MPGUI:Main

Menu>Preprocessor>MaterialProps>MaterialModels>ThermalThematerialpropertiescanbeinputasnumericalvaluesorastableinputsforsomeelements.Tabularmaterialpropertiesarecalculatedbeforethefirstiteration(i.e.,usinginitialvalues[IC]).SeetheMPcommandformoreinformationonwhichelementscanusetabularmaterialproperties.Todefinetemperature-dependentproperties,youfirstneedtodefineatableoftemperatures.Then,definecorrespondingmaterialpropertyvalues.Todefinethetemperaturestable,useeitherofthefollowing:Command(s):MPTEMPorMPTGEN,andtodefinecorrespondingmaterialpropertyvalues,useMPDATA.GUI:Main

Menu>Preprocessor>MaterialProps>MaterialModels>ThermalUsethesameGUImenuchoicesorthesamecommandstodefinetemperature-dependentfilmcoefficients(HF)forconvection.Caution:Ifyouspecifytemperature-dependentfilmcoefficients(HF)inpolynomialform,youshouldspecifyatemperaturetablebeforeyoudefineothermaterialshavingconstantproperties..

UsingtheSurfaceEffectElementsYoucanusethesurfaceeffectelements(SURF151,SURF152)toapplyheattransferforconvection/radiationeffectsonafiniteelementmesh.ThesurfaceeffectelementsalsoallowyoutogeneratefilmcoefficientsandbulktemperaturesfromFLUID116elementsandtomodelradiationtoapoint.Youcanalsotransferexternalloads(suchasfromCFX)toANSYSusingtheseelements.Theguidelinesforusingsurfaceeffectelementsfollow:Createandmeshthethermalregionasdescribedabove.UseESURFtogeneratetheSURF151orSURF152elementsonthesurfacesofthefiniteelementmesh.ForSHELL131andSHELL132models,youmustuseSURF152.SetKEYOPT(11)=1forthetoplayerandKEYOPT(11)=2forthebottomlayer.ForFLUID116models,theSURF151andSURF152elementscanusethesingleextranodeoption(KEYOPT(5)=1,KEYOPT(6)=0)togetthebulktemperaturefromaFLUID116element(KEYOPT(2)=1).SURF151andSURF152elementscanalsobeusedtodefinefilmeffectivenessonaconvectionsurface.Formoreinformationonfilmeffectiveness,seeConductionandConvectionintheTheoryReferencefortheMechanicalAPDLandMechanicalApplications.Forgreateraccuracy,theSURF151andSURF152elementscanusetheoptionoftwoextranodes(KEYOPT(5)=2,KEYOPT(6)=0)togetbulktemperaturesfromFLUID116elements(KEYOPT(2)=1).Fortwoextranodes,youmustsetKEYOPT(5)to0beforeissuingtheESURFcommand.AfterissuingESURF,yousetKEYOPT(5)to2andissuetheMSTOLEcommandtoaddthetwoextranodestotheSURF151orSURF152elements.ThefollowingmethodsareavailableformappingtheFLUID116nodestotheSURF151orSURF152elementswithMSTOLE.Minimumcentroiddistancemethod:ThecentroidsoftheFLUID116andSURF151orSURF152elementsaredeterminedandthenodesofeachFLUID116elementaremappedtotheSURF151orSURF152elementthathastheminimumcentroiddistance.Theminimumcentroiddistancemethodwillalwayswork,butitmightnotgivethemostaccurateresults.Figure

2.1

MinimumCentroidDistanceMethodProjectionmethod:ThenodesofaFLUID116elementaremappedtoaSURF151orSURF152elementiftheprojectionfromthecentroidoftheSURF151orSURF152elementtotheFLUID116elementintersectstheFLUID116elementperpendicularly.AerrormessageisissuedIfaprojectionfromaSURF151orSURF152elementdoesnotintersectanyFLUID116elementperpendicularly.Figure

2.2

ProjectionMethodHybridmethod:Thehybridmethodisacombinationoftheprojectionandminimumcentroiddistancemethods.Inthismethod,theprojectionmethodistriedfirst.Iftheprojectionmethodfailstomapcorrectly,aswitchismadetotheminimumcentroiddistancemethod.Anynecessaryswitchingisdoneonaper-elementbasis.IftheFLUID116elementlengthsvarysignificantlyasshowninthefollowingtwofigures,theprojectionmethodisbetterthantheminimumcentroiddistancemethod.TheminimumcentroiddistancemethodwouldmapthenodesoftheshorterFLUID116elementtotheSURF151orSURF152element,buttheprojectionmethodwouldmapthenodesofthelongerFLUID116elementtotheSURF151orSURF152element.Figure

2.3

VaryingFLUID116ElementLength-MinimumCentroidDistanceMethodFigure

2.4

VaryingFLUID116ElementLength-ProjectionMethodTheprojectionmethodwillnotmapanyFLUID116nodestotheSURF151orSURF152elementsthatarecircledinthefollowingfigure.However,thehybridmethodwillworkbecauseaswitchwillbemadetotheminimumcentroiddistancemethodonthesecondpass.Figure

2.5

ProjectionMethodFailsforCertainElementsSolvetheanalysis.ForexampleproblemsusingSURF152withaFLUID116model,seeVM271intheVerificationManualandThermal-StressAnalysisofaCooledTurbineBladeintheTechnologyDemonstrationGuide.Forinformationinusingsurfaceeffectelementstomodelradiationtoapoint,seeModelingRadiationBetweenaSurfaceandaPoint.ForinformationontransferringexternalloadsfromCFXtoANSYS,seetheANSYSCFX-Posthelp,ortheCoupled-FieldAnalysisGuide..

CreatingModelGeometryThereisnosingleprocedureforbuildingmodelgeometry;thetasksyoumustperformtocreateitvarygreatly,dependingonthesizeandshapeofthestructureyouwishtomodel.Therefore,thenextfewparagraphsprovideonlyagenericoverviewofthetaskstypicallyrequiredtobuildmodelgeometry.Formoredetailedinformationaboutmodelingandmeshingproceduresandtechniques,seetheModelingandMeshingGuide.Thefirststepincreatinggeometryistobuildasolidmodeloftheitemyouareanalyzing.Youcanuseeitherpredefinedgeometricshapessuchascirclesandrectangles(knownwithinANSYSasprimitives),oryoucanmanuallydefinenodesandelementsforyourmodel.The2-Dprimitivesarecalledareas,and3-Dprimitivesarecalledvolumes.Modeldimensionsarebasedonaglobalcoordinatesystem.Bydefault,theglobalcoordinatesystemisCartesian,withX,Y,andZaxes;however,youcanchooseadifferentcoordinatesystemifyouwish.Modelingalsousesaworkingplane-amovablereferenceplaneusedtolocateandorientmodelingentities.Youcanturnontheworkingplanegridtoserveasa"drawingtablet"foryourmodel.Youcantietogether,orsculpt,themodelingentitiesyoucreateviaBooleanoperations,Forexample,youcanaddtwoareastogethertocreateanew,singleareathatincludesallpartsoftheoriginalareas.Similarly,youcanoverlayanareawithasecondarea,thensubtractthesecondareafromthefirst;doingsocreatesanew,singleareawiththeoverlappingportionofarea2removedfromarea1.Onceyoufinishbuildingyoursolidmodel,youusemeshingto"fill"themodelwithnodesandelements.Formoreinformationaboutmeshing,seetheModelingandMeshingGuide.2.5.

ApplyingLoadsandObtainingtheSolutionYoumustdefinetheanalysistypeandoptions,applyloadstothemodel,specifyloadstepoptions,andinitiatethefiniteelementsolution..

DefiningtheAnalysisTypeDuringthisphaseoftheanalysis,youmustfirstdefinetheanalysistype:IntheGUI,choosemenupathMain

MenuSolution>AnalysisType>NewAnalysis>Steady-state(static).Ifthisisanewanalysis,issuethecommandANTYPE,STATIC,NEW.Ifyouwanttorestartapreviousanalysis(forexample,tospecifyadditionalloads),issuethecommandANTYPE,STATIC,REST.YoucanrestartananalysisonlyifthefilesJobname.ESAVandJobname.DBfromthepreviousrunareavailable.IfyourpriorrunwassolvedwithVTAccelerator(STAOPT,VT),youwillalsoneedtheJobname.RSXfile.Youcanalsodoamultiframerestart..

ApplyingLoadsYoucanapplyloadseitheronthesolidmodel(keypoints,lines,andareas)oronthefiniteelementmodel(nodesandelements).Youcanspecifyloadsusingtheconventionalmethodofapplyingasingleloadindividuallytotheappropriateentity,oryoucanapplycomplexboundaryconditionsastabularboundaryconditions(seeApplyingLoadsUsingTABLETypeArrayParametersintheBasicAnalysisGuide)orasfunctionboundaryconditions(see"UsingtheFunctionTool").Youcanspecifyfivetypesofthermalloads:.1.

ConstantTemperatures(TEMP)TheseareDOFconstraintsusuallyspecifiedatmodelboundariestoimposeaknown,fixedtemperature.ForSHELL131andSHELL132elementswithKEYOPT(3)=0or1,usethelabelsTBOT,TE2,TE3,...,TTOPinsteadofTEMPwhendefiningDOFconstraints..2.

HeatFlowRate(HEAT)Theseareconcentratednodalloads.Usethemmainlyinline-elementmodels(conductingbars,convectionlinks,etc.)whereyoucannotspecifyconvectionsandheatfluxes.Apositivevalueofheatflowrateindicatesheatflowingintothenode(thatis,theelementgainsheat).IfbothTEMPandHEATarespecifiedatanode,thetemperatureconstraintprevails.ForSHELL131andSHELL132elementswithKEYOPT(3)=0or1,usethelabelsHBOT,HE2,HE3,...,HTOPinsteadofHEATwhendefiningnodalloads.Note:Ifyouusenodalheatflowrateforsolidelements,youshouldrefinethemesharoundthepointwhereyouapplytheheatflowrateasaload,especiallyiftheelementscontainingthenodewheretheloadisappliedhavewidelydifferentthermalconductivities.Otherwise,youmaygetannon-physicalrangeoftemperature.Wheneverpossible,usethealternativeoptionofusingtheheatgenerationrateloadortheheatfluxrateload.Theseoptionsaremoreaccurate,evenforareasonablycoarsemesh..3.

Convections(CONV)Convectionsaresurfaceloadsappliedonexteriorsurfacesofthemodeltoaccountforheatlostto(orgainedfrom)asurroundingfluidmedium.Theyareavailableonlyforsolidsandshells.Inline-elementmodels,youcanspecifyconvectionsthroughtheconvectionlinkelement(LINK34).Youcanusethesurfaceeffectelements(SURF151,SURF152)toanalyzeheattransferforconvection/radiationeffects.Thesurfaceeffecteleme