workbench动力学分析实例.ppt

Workshop2SimulatetheCrushingofanEmptySodaCan,WorkshopGoalandProcedure,Goal:Crushanaluminumbeveragecanandallowitto“springback”Procedure:CreateanExplicitDynamics(ANSYS)AnalysisSystemProjectSelecttheunitssystemanddefinethematerialpropertiesImport,modify,andmeshthesodacangeometryDefineanalysissettings,boundaryconditions,andexternalloadsInitiatethesolution(AUTODYN-STR)andreviewtheresults,Step1CreatetheProjectSchematic,StartANSYSWorkbenchandfollowthesequencedstepsusingtheabbreviationsshownbelow:DC=DoubleClickwithLeftMouseButtonSC=SingleClickwithLeftMouseButtonRMB=RightMouseButtonSelectionD&D=DragandDrop=HoldLeftMouseButtondownonitemwhiledraggingittonewlocationandthenreleaseit(i.e.,CopyorMove),DC,1.CreateanANSYSExplicitDynamicsAnalysisSystemProject,Step2SpecifytheProjectUnits,2.aSelectMKSfortheProjectUnitsfromtheUnitsListprovided2.bRequestthatNativeApplicationsinWorkbenchhavetheirvaluesbeDisplayedintheProjectUnits2.cCheckthoseunitsystemstoSuppressfromappearingintheUnitsList,Note:EngineeringDataisnativeinWorkbench,butMechanicalisNOTatthistime(butwillbeinthefuture).,Step3DefineEngineeringDataMaterial,3.aEdittheEngineeringDatacelltoaddamaterialtothedefaultlibrary.3.bSelectthelastslotunderEngineeringDatatodefineanewmaterialmodel.,SC,3.cEntermaterialmodelname:“My_Aluminum”,Note:AnexistingmaterialmodelintheExplicitMaterialslibrarycouldhavebeenselected,buttherearerestrictionsonelementtypesthatcanbeusedwithcertainmaterialmodels,whichwillbediscussedlater.,DC,DC,DC,DC,Step3DefineEngineeringDataMaterial.,SC,3.eAddthefollowingPhysicalPropertiestothematerialdefinition:DensityIsotropicElasticityBilinearIsotropicHardening,3.dMakesurethenewmaterialisactiveinordertodefineitsproperties,Step3DefineEngineeringDataMaterial.,3.fEnterthefollowingvalues:Density=2710kgm-3YoungsModulus=7e10PaPoissonsRatio=0.30YieldStrength=2.9e8PaTangentModulus=0.0PaSincethematerialissufficientlydefined,thebluequestionmarksandyellowfieldsarenolongerpresentinthedatatable.Note:Theresultingstress-straincurveiselasticperfectlyplastic.Nostrainhardeningcandevelop.,Step3DefineEngineeringDataMaterial.,3.gReturntotheProjectSchematic3.hSavetheProjectbyselectingthe“SaveAs.”iconandBrowsetothedirectoryindicatedbyyourinstructor.Usethename“empty_soda_can”fortheProjectname.,Note:SavingtheProjectsavesalloftheimportantfiles.TheProjectmayalsobeArchived,inwhichallofthesupportingfilesarecompressedandsavedinonefile.,Step4ImportandModifytheGeometry,4.cWorkbenchhasnowidentifiedthegeometryfile(notegreencheckmarkinGeometrycell).ItisnowOKtoDoubleClickon“Geometry”,asthenewdefaultactionistoEditthegeometry.DefaultactionsareshowninboldtypeafterRMBselects.,RMB,SC,4.aImportthegeometrybytheprocedureshown.DoNOTDoubleClickonthe“Geometry”cell.,4.bBrowsetotheDesignModeler11.0SP1geometryfilenamed:“soda_can_filled_110.agdb”,RMB,SC,Step4ImportandModifytheGeometry.,4.dSuppressthesolid“Soda”andthesurfacebody“Hole”.,RMB,SC,4.eGeneratethechangesinthegeometry.Althoughadditionalmodificationscouldbemade,butnoneareneeded.,4.fSavetheentireProjectviatheDM“Save”icon.,Step5EdittheModelinMechanical,5.aEditthemodelinWorkbenchMechanical.,SinceEditisthedefaultaction,double-clickingontheModelcellisalsoacceptablehere.,RMB,SC,5.bSelecttheMKSUnitssystemRecallthatMechanicalisnotnativeinWorkbench,sotheUnitsheremaynotmatchtheProjectUnitsNote:Althoughtheunitsystemusedfordataentryandpost-processingistheMKSsystem,theactualunitsystemusedbytheAUTODYNsolveristhemm-mg-mssystem,becauseitprovideshigheraccuracy.ThiswillbeshownlaterwhentheAnalysisSettingsarediscussed.,Step5EdittheModelinMechanical.,RigidSteelPunch(moveddownwards),FlexibleAluminumSodaCan(crushed),RigidSteelDie(fixed),5.cDefinetheAluminumCanproperties:StiffnessBehavior=FlexibleThickness=0.00025metersMaterialAssignment=My_Aluminum,5.dDefinethePunchandDieproperties:StiffnessBehavior=RigidMaterialAssignment=StructuralSteel,Step5EdittheModelinMechanical.,5.eReviewtheContactspecifications,Keepcontactdefinitiondefaults,5.fSavetheProject,Note:ThereisnoSaveiconinMechanical,Step6SetSizingControlsandMeshModel,6.dOrientthemodeltoselectthe8edgesthatdefinethecancircumferences(withtheLeftMouseButton).UsetheCtrlkeyformultipleselections,asneeded.,6.aSelecttheMeshbranch6.bSpecifytheMeshDetails:PhysicsPreference=ExplicitElementSize=0.010meters6.cChoosetheEdgeselectionfilter,RMB(anywhere),6.eWiththe8edgesstillhighlighted,Insert(RMBanywhereongraphicsscreen)anEdgeSizing,SC,SC,Step6SetSizingControlsandMeshModel.,6.fSpecifytheEdgeSizingDetails:Type=NumberofDivisionsNumberofDivisions=36Behavior=Hard6.gGeneratetheMesh(RMBoneitherMeshbranchorEdgeSizingbranch),RMB,SC,Meshview,Step7DefinetheAnalysisSettings,7.aSpecifytheAnalysisSettings:EndTime=6.0e-4secondsAutomaticMassScaling=YesMinimumCFLTimeStep=1.0e-7sec,SC,7.bSettheSolveUnits=mm,mg,msNote:Themm,mg,msunitsystemisthemostaccurateinmostsimulations,soitistheonlyonecurrentlyavailable.Althoughmoresolverunitsystemswillbeavailableinthefuture,anyunitsysteminthedrop-downlistmaybeusedtoenterdataand/ordisplaytheresults.,Step7DefinetheAnalysisSettings.,7.cKeeptheremainingdefaultsNote:Therearemultiplewaystocontroltheerosionofanelement.Inthiscase,theelementwillonlyfailwhenthegeometricstrainreaches150%.7.dUsethedefaultnumberofdatasetstosaveduringthesolution.Dependingontheanalysis,thisnumbermayneedtobeincreased,butthatrequiresadditionaldiskspace,sobejudicioushere.,Step8ApplyBCsandExternalLoads,8.aFixtheSteelDie(base):SelecttheBodyfilterInsertaFixedSupportunderExplicitDynamicsSelectthesteeldieApplytheselection,RMB,SC,SC,Step8ApplyBCsandExternalLoads.,8.bDisplacetheSteelPunchInsertaDisplacementunderExplicitDynamicsSelectthesteeldieApplytheselection,RMB,SC,SC,Step8ApplyBCsandExternalLoads.,Note:Thepunchspeedandabruptchangeindirectionareunrealistic,butsufficientfordemonstrationpurposes.Normally,themovementwouldbeprescribedaccordingtoaSINEwavefunction.,8.cSpecifythevertical(Y)displacementtobeaTabularloadandsetboththeXandZdisplacementstobezero.8.dRamptheYdisplacementasfollows:Time=0.0secY=0.0metersTime=5e-4secY=-0.060metersTime=6e-4secY=-0.030meters,Step9InsertResultItemstoPostprocess,9.aInsertaTotalDeformationplotrequestundertheSolutionbranch.9.bInsertanEquivalent(von-Mises)StressplotrequestundertheSolutionbranch.Therigidbodies(i.e.,thepunchanddie)willnotshowstress.,RMB,RMB,SC,SC,SC,SC,SC,SC,Step9InsertResultItemstoPostprocess.,9.cInsertanEquivalentPlasticStrainplotrequestundertheSolutionbranch.,RMB,SC,SC,SC,Note:Eventhoughasingletimepoint(attheendoftherun)isspecified,thecompletesetofresultscanbeviewed,includinganimations.Recallthatthedefaultoutputcontrols(20equallyspacedtimepoints)wasretainedundertheAnalysisSettingsbranch.,9.dSavetheProjectagain.,Step10RuntheAUTODYNSimulation,10.aSelectSolverOutputunderSolutionInformationandSolvethesimulation.,TheSolverOutputshowstherunstatistics,includingtheestimatedclocktimetocompletion.Anyerrorsorwarningsarealsonoted.Terminationdueto“wrapuptimereached”isexpectedhere.,SC,Step10RuntheAUTODYNSimulation.,10.bSelectEnergySummaryunderSolutionInformationtoreviewtheglobalstatistics.Notetheabruptchangesinkineticenergyduetotheunrealisticloadingscenario.,TIME=5.0e-4secondsoccursaround3200cyclesintorun,Constantvelocityafterstartingfromrest,Step11ReviewtheResults,11.aSelectTotalDeformationandShowtheElementsunderTrueScale.Themaximumdeformation(-0.060m)exceedsthepunchvalueduetothemomentuminvolved(i.e.,anexcessivepunchspeedwasusedtoreducetherequiredcomputerruntime).,SC,Step11ReviewtheResults.,11.bAnimatetheresultsbysettingthecontrolsasshownbelowandthenpressingtheAnimationbutton.Fortransientdynamics,thedefaultDistributedmodeisinadequate,asitlinearlyinterpolatesbetweensavedresults.TheResultSetsmodeisoptimal,asitusestheactualsaveddata.Toreviewastaticresult,justclickonthedesiredTimeorValuefromtheTabularDataandusetheRMBtopickRetrieveThisResult.Thegivenstatewillthenbeshown.,RMB,Pickthese2first,Thenpickthis,Pickthistosavetheanimation,Toretrieveagivenresult.,Step11ReviewtheResults.,11.cRepeattheprocedure,ifdesired,forthevon-Misesequivalentstressresults.Note:Nostresscandevelopinarigidbody.ThepunchanddieareeachcondensedouttoamassattheirrespectivecentersofgravitywithsixDOFsactive.,Contactisbasedontheexteriorsurface,soasixDOFbodycanhaveacomplicatedcontactsurface.,SC,Step11ReviewtheResults.,11.dRepeattheprocedureonelasttimefortheequivalentplasticstrainresults.11.e.HidethePunchandDieforabetterviewoftheresults.PertheAnalysisSettings,erosiondoesnotoccuruntilthegeometricstrainis1.50,SC,SC,RMB,Step12ReviewtheOutputFiles,12.aPickFilesundertheViewmenutoaccesstheProjectfiles,12.bSelectOpenContainingFolderviatheRMBoptionfortheAUTODYNprintfile(admodel.prt).,RMB,Step12ReviewtheOutputFiles.,12.cDoubleclickonthefileadmodel.prt,12.dAsnotedearlier,thesolverunitssystemwasmm-mg-msinordertomaximizetheaccuracy.AftertheSimulationisdone,theresultsareconvertedbackintothecurrentMechanicalunitssystem.,Step12ReviewtheOutputFiles.,12.eTheAUTODYNprintfilealsocontainstheMaterialSummaryinformationandrunstatistics.TheEnergyandMomentumareshownonbothamaterialbasisandaPartbasis(shownhere).,Step12ReviewtheOutputFiles.,12.fTheEnergyandMomentumBalance,MassScaling,andRunTimesarealsoincludedintheadmodel.prtfile.,12.gNomasswasaddedtothemodel,sincethetimestepswereallabovetheMinimumCFLTimeStepof1.0e-7secs