UG刚柔耦合仿真分析

1・lnthislessonAftercompletingthislesson,youwillbeableto:CreateanSEMODES103-FlexibleBodysolutioninAdvancedSimulation.Connecttheflexiblebodyfiniteelementmodeltothedegreesoffreedominthemotionmechanism.SolvethefiniteelementmodelandgeneratetheRecurDynRflexinputfile・DefinetheflexiblebodyinMotionSimulationandsolvethemotionmechanism・Animatethemotionmechanismandobservetheflexiblebodydeformation・✓✓OverviewTypicalmotionsimulationsrepresentmechanismsusingrigidbodiesthatmoveinprescribeddegreesoffreedomaccordingtoconstraints.Theserigid-bodymotionsimulationscannotrepresentcertaindynamiccharacteristics,especiallythoseresultingfromconditionssuchassharpimpacts,suddenchangesinmotion,orwhenthecomponentisflexibleenoughtoaffectthemotionofthemechanism.Forthesesituations,youcanuseaflexiblebodyanalysistocombinebothelasticdeformationandrigidbodymotion.ThistypeofanalysisrequiresNXMotionSimulationwiththeRecurDynsolverandNXAdvancedSimulationwiththeNXNastransolver.Tosetupaflexiblebodyanalysisforacomponentinyourmechanism,youcreateafiniteelementmodelonthecomponentanddefinestiffnessatthepointswhereitisconnectedtothemechanism(typicallyatjointlocations).TheNXNastranSEMODES103-FlexibleBodysolutionreducesthedynamicbehavioroftheflexiblebodytoasetofmodeshapes,whicharestoredinanoutputfile.Afteryousolvethismodalsolution,youassociatetheflexiblebodyoutputfile(.rfifile)withthelinkonwhichthecomponentisdefinedinthemotionsimulation.Whenyousolvethemotionsimulation,theRecurDynsolvercommunicateswithNXNastranandrecoverstheFEresults.Whenyouanimatethemechanism,thecontourplotfortheflexiblecomponentisanimatedalongwiththerigidbodyanimation.3.WorkflowAdvancedSimulationstepsCreateafiniteelementmodelandNXNastranSEMODES103-FlexibleBodysolution.Createafiniteelementmeshontheflexiblecomponentandassignmaterialproperties.Usea1DConnection(spiderelement)orotherconstraintelementstodefinethecomponent'sconnectionpointstothemechanism.AddFixedBoundaryDegreesofFreedomconstraintstodefineconnectiondegreesoffreedom.AddFreeBoundaryDegreesofFreedomconstraintstodefineloaddegreesoffreedom.Solvethemodalsolution.ARecurDynRflexinput(.rfi)fileisgeneratedfortheflexiblelink.Repeatsteps16foreachadditionalflexiblecomponentinthemechanism.MotionSimulationstepsCreateaFlexibleBodyDynamicsmotionsimulation.Createflexiblelinksontheflexiblecomponents.Associateeach.rfifilewitheachflexiblelink.CreateaFlexibleBodysolutionandaddtheflexiblelinkstothesolution.Solvethemechanism.

RunAnimationtoviewthecombinedrigidbodyandflexiblebodymotion.Plotthemodaldegreesoffreedomvs.timetodeterminethecontributionofselectedmodestotheflexiblebodyresults.Youcanselectoneormoremodesoftheflexiblebodyandthenplotthemodaldisplacement,acceleration,orvelocity.4.Activity:Flexiblebodyanalysis—IntroductionEstimatedtimetocomplete:12-16minutesYouwilllearnhowto:DefinetheflexiblebodyinMotionSimulationandsolvethemotionmechanism.Animatethemotionmechanismandobservetheflexiblebodydeformation.NoteTocompletethisactivity,youmusthavethenx_motion_rflexlicense,inadditiontoMotionSimulation,AdvancedSimulation,andNXNastran.LaunchtheFlexiblebodyanalysis一Introductionactivity.5.AbouttheflexiblebodymodalsolutionYouwillusetheAdvancedSimulationapplicationtocreateafiniteelementmodeloftheflexiblebodyandperformamodalanalysis.Amodalanalysissolvesforthenaturalfrequenciesandmodeshapesofflexiblebodies.TheNXNastranSEMODES103-FlexibleBodymodalsolutionreducestheflexiblebody'smassandstiffnesstomodalspacetorepresentitsdynamicbehavior.ThesereducedmatricesaresavedintheRecurDynRflexinputfile(.rfi).Then,inMotionSimulation,youassociatethe.rfifilewithalinktocreatetheflexiblelink.

Examplemodeshapes6.AboutthefiniteelementmeshThefiniteelementmodelofagivenbodyconsistsofafiniteelementmesh,materialproperties,andconstraints.Whenyoucreateameshonthebody,thesoftwaredividesthebodyintodiscreteregionscalledelementsthatarejoinedtogetheratpointscallednodes.Agroupofelementsiscalledamesh.Themeshfollowstheshapeofthebody.Whenthemodelissolved,asthenodesinthemesharedisplacedduetotheanalysisconditionssuchasloads,thebehaviorofeachelementisdescribedbymathematicalequations.Thesoftwarefindstheanalysissolutionbysummingtheindividualelementsolutions.

ExamplemeshoftetrahedralelementsInAdvancedSimulation,youcreatethemeshintheFEMfile.Whenyouuseasmallerelementsize(resultinginmoreelementsinamesh),theaccuracyofthesolutionisimproved.However,asyourefinethemesh,thesolutiontimeandcomputerresourcesneededtosolvearealsoincreased.7.AssigningamaterialtothemeshInMotionSimulation,materialpropertiesforacomponentareinheritedfromthemastermodelonwhichyoucreatethesimulation.InAdvancedSimulation,youmustassignthesamematerialtotheflexiblebodyfiniteelementmeshasthematerialusedfortheflexiblelinkinMotionSimulation.Toassignamaterialtothemesh,editthemeshcollectorthatcontainsthemesh.Then,modifythephysicalpropertytableforthecollectorandopentheMaterialListdialogbox,whereyoucanselectthematerialtouse.

ConnectingtheflexiblebodyFEMtothemechanismInAdvancedSimulation,intheFEMfile,youmustdefinethepointswheretheflexiblebodyisconnectedtothemotionmechanism.Theseconnectionpointsmustbedefinedattheoriginpointofeveryjoint,bushing,force,torque,spring,ordampermotionobjectontheflexiblebody.Althoughyoucanuseanyelementtypetodefinetheseconnectionpoints,typicallyyouwillusea1DConnection(spiderelement).Foraccuracyinyourflexiblebodysolution,asingleindependentnode(suchasthecorenodeofthespiderelement)inthisconnectionelementshouldbecoincidentwiththemotionobject'soriginpoint.Youwilldefinestiffnessatthisconnectionnodeusingspecialconstraintsdescribedinthenextsection.

SpiderelementsdefinedatrevolutejointlocationsMakesuretheconnectionnodeisatalocationthatcreatesbalancedloading.Forexample,supposeyouareconnectingtheflexiblebodytoarevolutejointthatisdefinedonahole.Definetheconnectionnodeintheborecenterofthehole,ratherthanattheedgeofthehole.Exampleofpinnedconnection(Revolutejointdefinedatborecenterofhole)

ConnectionnodeimproperlydefinedatedgeofholeConnectionnodeproperlydefinedatborecenterofholeDefiningconnectionandloaddegreesoffreedomInAdvancedSimulation,intheSimulationfile,youmustaddspecialconstraintstodefinetheconnectionandloaddegreesoffreedomfortheflexiblebody.AteachconnectionnodewheretheflexiblebodywillbeconnectedtothemechanismthroughajointorbushinginMotionSimulation,createaFixedBoundaryDegreesofFreedomconstrainttodefinetheconnectiondegreesoffreedom.Ateachconnectionnodewhereaforce,torque,spring,ordamperwillbeappliedtotheflexiblebodyinMotionSimulation,createaFreeBoundaryDegreesofFreedomconstrainttodefinetheloaddegreesoffreedom.

SolvingtheNXNastranmodalsolutionIntheSolutiondialogboxfortheSEMODES103-FlexibleBodysolution,youmustspecifythenumberofmodesforwhichtosolveandtheresulttypestorecover.Bydefault,stressanddisplacementresultsareselected.Afteryouhavedefinedthefiniteelementmesh,connectionandloaddegreesoffreedom,andsolutionattributes(suchasthenumberofdesiredmodes),youcansolvethemodel.

r](^Inirhvri口arifiTiRrropvrtMi![ttHlW[emh.|BQE~ueya:aL典匚putR亡qo亡》再JiWWVKPf[CW4KR|M^|jWWim«；►e'liQW-AiiM.tiHdftMter.mnirj上rhcfiran—Jr](^Inirhvri口arifiTiRrropvrtMi![ttHlW[emh.|BQE~ueya:aL典匚putR亡qo亡》再JiWWVKPf[CW4KR|M^|jWWim«；►e'liQW-AiiM.tiHdftMter.mnirj上rhcfiran—J咗f™[ifcM.ira—J^iiK^DnMimlimfinquerKfOfAma^"^Hicc^'^ngii-La«*■*■*LmriwyHC■曲也iowe*hol'VlOTiLIIXEASTF^HSUKX££创TitcabUBortSTOE35Qnkii*|iS^isLD]-tljeKiijjeSd7|3tEU：tUEQ丄TtaUi-w^wi:hghWffHiBu^ingMecx*L!bijm*Z«frwTd«iR441F44*»FM*-~阳-W^MVGWI管0更1555IThesolveproducesseveralresultsfilesthatyoumustnotdelete,move,orrename:.dat—Nastraninputfile,neededforlaterresultsrecovery..op2—Containsthemodelgeometryandcomponentmodesresultingfromthemodalanalysis._0.op2—Neededforlaterresultsrecovery;containsthecomponentmodedefinitions,modalmass,andmodalstiffness..rfi—RecurDynRflexinputfile,neededforrepresentingtheflexiblebodyintheRecurDynsolve.Rememberthelocationofthe.rfifilebecauseyouwillneedtopointtoitwhencreatingtheflexiblelinkinMotionSimulation.ReviewQuestionInthefollowingexample,supposeyouaredefiningthisexcavatorbucketas

aflexiblebodyinAdvancedSimulation.Inthemotionmechanism,asinglerevolutejointisdefinedbetweenthetwoholes(1inthegraphicbelow)atthetopofthebucket.Aforceloadisappliedtooneoftheteeth(2).InAdvancedSimulation,whichconstraintsmustyouapplybeforesolvingtheSEMODES103-FlexibleBodysolution?2TwoFixedconstraintsTwoFixedconstraintsAFixedTranslationconstraintandaPinnedconstraintAFixedBoundaryDegreesofFreedomconstraintandaFreeBoundaryDegreesofFreedomconstraintAUserDefinedconstraintandaPinnedconstraintAftersolvingtheSEMODES103-FlexibleBodysolution,whenyoucreatetheflexiblelinkinMotionSimulation,whatfilemustyouassociatewiththelinktorepresentthedynamicbehavioroftheflexiblebodyinthemechanism?The.RFIfileThe.RFIfileThe.DATfile(Nastraninputdeck)The.DATfile(Nastraninputdeck)The.OP2fileThe.MDFfileThe.OP2fileThe.MDFfileShowfeedback12.Activity:Flexiblebodyanalysis—AdvaneedSimulationtasksEstimatedtimetocomplete:12-16minutesYouwilllearnhowto:守密~CreateanSEMODES103-FlexibleBodysolutioninAdvancedSimulationandspecifyabodyasflexible.IConnecttheflexiblebodyfiniteelementmodeltothedegreesoffreedominthemotionmechanism.

SolvethefiniteelementmodelandgeneratetheRecurDynRflexinputfile.NoteTocompletethisactivity,youmusthavethenx_motion_rflexlicense,inadditiontoMotionSimulation,AdvancedSimulation,andNXNastran.LaunchtheFlexiblebodyanalysis一AdvancedSimulationtasksactivity.thatisassociated13.DefiningtheflexiblelinkinthemechanismthatisassociatedInMotionSimulation,youmustcreateaFlexibleLinkwiththecomponentorbodythatyoudefinedasflexibleinAdvancedSimulation.IntheFlexibleLinkdialogbox,youassociatethelinkwiththeRecurDyninputfile(.rfifile)generatedbytheNXNastranmodalsolution.TheFlexibleLinkPreviewwindowhelpsyoudeterminethecorrectmethodforpositioningtheflexiblebodyonthelink.Inthegraphicswindow,theflexiblelinkisdisplayedwithitsfiniteelementmesh.

Meshedflexiblelinkdefinedinthemechanism(andPreviewview)ChoosingmodestoineludeintheanalysisBydefault,allmodesfromtheNXNastranmodalsolutionareincludedinthemotionsimulationsolveexceptthefirstsixmodes,whichareconsideredrigid-bodymodes.Includingallmodesensuresamoreaccuraterepresentationofthestructure.However,forbettersolveperformance,youcanreducethemodalmodelbyremovinginsignificantmodes.Todeterminewhichmodestoremove,youcanviewandanimatethemodeshapesusingthePostProcessingNavigatorandPostProcessingtoolbar.Makesuretoincludeallmodesthatresemblethebehavioryouareanalyzing.Examplemodeshape✓✓SolvingthemodelandanimatingthemechanismInMotionSimulation,youcreateaKinematics/DynamicssolutionoftypeFlexibleBody.WhenyousolvetheFlexibleBodysolution,theRecurDynsolvercalculatesthephysicaldeformationsateachpointwheretheflexiblebodyisconnectedtotherestofthemechanism,foreachconfigurationofthemotionmechanism.Itsavesthesedeformationsinamodaldeformationfile(.mdf).Usingthe.mdffile,themotionsolutionprocesscallstheNXNastransolvertorecoverthedeformation,displacement,stress,andotherresultsontheoriginal,unreducedflexiblebody.ThesetransientresultsarethenreturnedtoMotionSimulation,whereyoucanviewtheminananimationofthemechanism.Bydefault,whenyouanimateaflexiblebodysolution,translationaldeformationresults(nodaldisplacements)aredisplayedfortheflexiblebody.Youcanalsodisplayotherresults,suchasDisplacement-Nodal,Stress-Element-NodalandStrain-Element-Nodal,dependingontheresultsyourequestedintheoutputrequestfortheSEMODES103-FlexibleBodysolutioninAdvancedSimulation.Activity:Flexiblebodyanalysis—MotionSimulationtasksEstimatedtimetocomplete:12-16minutes

Youwilllearnhowto:DefinetheflexiblebodyinMotionSimulationandsolvethemotionmechanism.Animatethemotionmechanismandobservetheflexiblebodydeformationandstress.Runaninterferencecheckbetweentheflexiblelinkandabodypanel.NoteTocompletethisactivity,youmusthavethenx_motion_rflexlicense,inadditiontoMotionSimulation,AdvancedSimulation,andNXNastran.LaunchtheFlexiblebodyanalysis一MotionSimulationtasksactivity.Flexiblebodyanalysis—Introduction1OpentheMotionSimulationLookinintro_flex_body\FBcam_assy•FilesoftypeSimulationFiles(*.sim)V•Filenamemotion_1.simVpen(Standardtoolbar)OK

ThemotionsimulationopensintheMotionSimulationapplication.ResetthedialogboxsettingsTheoptionsyouselectinNXdialogboxesarepreservedforthenexttimeyouopenthesamedialogboxwithinanNXsession.Toensurethatthedialogboxesareintheexpectedinitialstateforeachstep-by-stepactivity,youshouldrestorethedefaultsettings.Preferences—UserInterfaceResetDialogBoxSettingsOKEnabletheFlexibleBodyDynamicsenvironmentTheFlexibleBodyDynamicsenvironmentisavailableonlywiththeDynamicsanalysistype.•OKFlexibleBodyDynamicsEnvironment(Motiontoolbar)•OKFlexibleBodyDynamics✓✓DefinetheflexiblelinkOKOKBOFlexibleModel••巴intro_flex_body/fbcam_assy_sim2-solution_1_0・rfiThispre-generatedfilecontainsamodalreductionoftheflexiblebody'smassandstiffness,whichrepresentsthebody'sdynamicbehavior.TheNXNastransolvergeneratesthesereducedmatricesandsavestheminaRecurDynRflexinput(RFI)file.Inalateractivity,youwillsolveanNXNastransolutionandgenerateanRFIfile.OKRFIFiledialogboxLeavetheFlexibleLinkdialogboxopenforthenextstep.5.FinishdefiningtheflexiblelinkTheFlexibleLinkdialogboxisstillopenfromthepreviousstep.•TheFlexibleLinkPreviewwindowshowsyouthemeshedflexiblebodyanditsorientationrelativetotheabsolutecoordinatesystem.

PlacementAbsoluteOrigin•Becausetheflexiblebodyisinthesameorientationrelativetotheabsolutecoordinatesystemasthecorrespondinglinkinthemechanism,AbsoluteOriginistheappropriateselection.okFlexibleLinkdialogbox6.CreateaFlexibleBodysolutionMotionNavigatorMotionNavigator•巴motion1••SolutionTypeSolutionTypeAnalysisTypeTimeStepsAddtheflexiblelinktothesolutionMotionNavigatorMotionNavigator□FlexibleLinks•巴L002-fbcam_assy_sim2-solution_1••SolvethemotionsimulationMotionNavigatorMotionNavigatorLoadContainer2•2•••Forillustrationpurposes,thisvectorforcesimulatesaloadontheclevisintheXdirection,toexaggeratetheflexiblebehavior.BSolution2Thesolveprocessmaytakeseveralminutestocomplete.AftertheRecurDynsolvefinishes,NXNastraniscalledautomaticallytoruntheSEMODES103-FlexibleBodysolve.NastranusestheRecurDynresultsfileandtheoriginalNXNastraninputfiletorecoverthedeformation,displacement,stressandotherresultsfortheflexiblelink.CautionDoNOTcloseanysolvewindowsuntilallNXNastrancommandpromptwindowshaveclosedandthemessage—Nastranresultsrecoverycompleted”appearsintheNXstatusline.AnimatethemechanismOKOKOKOKPlay此处为动图，有需要可联系上传者）Play此处为动图，有需要可联系上传者）Animation(Motiontoolbar,SimulationDrop-downlist)Bydefault,thecontourplotoftheflexiblelinkdisplaysnodaltranslationaldeformationresults.Youcanalsodisplayotherresults,suchasDisplacement-NodalandStress-Element-Nodal,dependingontheresultsyourequestedintheoutputrequestfortheSEMODES103-FlexibleBodysolutioninAdvancedSimulation.OKYoucompletedtheactivity.Flexiblebodyanalysis—AdvaneedSimulationtasks1Openthesimulation••Lookinf1_car_flex_body\_demo_assy•FilesoftypeSimulationFiles(*.sim)•Filenamemotion_1.simV•ThemotionsimulationopensintheMotionSimulationapplication.2.ResetthedialogboxsettingsTheoptionsyouselectinNXdialogboxesarepreservedforthenexttimeyouopenthesamedialogboxwithinanNXsession.Toensurethatthedialogboxesareintheexpectedinitialstateforeachstep-by-stepactivity,youshouldrestorethedefaultsettings.Preferences—UserInterfaceResetDialogBoxSettingsOKSolveandanimatethesolutionBeforeaddingtheflexiblebody,solveandanimatetheincludedsolutiontoseetherigid-bodymotionofthemechanism.MotionNavigatorBSolution1MotionNavigatorBSolution1Animation(Animation(Motiontoolbar,SimulationDrop-downlist)PackagingOptionsInterferencePauseonEventPackagingOptionsInterferencePauseonEvent•AnInterferencepackagingoptionhasbeenpredefinedbetweenthesuspensionarmandthesheetbodypanel.Whenyouanimatethemechanism,ifthesuspensionarmandbodypanelcomeintocontact,theinterferingbodieswillbehighlightedandtheanimationwillpause.••Asyoucansee,nointerferenceoccurs.Laterinthisactivity,wewillcheckforinterferenceagainwiththesuspensionarmdefinedasaflexiblelink.OKStartAdvaneedSimulationMotionNavigatorMotionNavigatorB_demo_assy••Thiseommandehangestheworkpartfromthemotionsimulationtothepartfile.NoSaveSimulationPartFilemessageStart—AdvancedSimulationCreateSimulationandFEMfilesSimulationNavigatorB_demo_assy.prt•••BodiestoUsethelowersuspensionarm)•BodiestoUsethelowersuspensionarm)TheNewFEMandSimulationdialogboxliststhethreenewfilesthatwillbecreated:theSimulation,FEM,andidealizedpartfile.TheSolverEnvironmentsectionlistsNXNastranasthesolver.TheAnalysisTypeisStructural.SelectokNewFEMandSimulationdialogbox•TheSolutiondialogboxappears.SolutionTypeSEMODES103-冋exibleBodySolutionTypeCaseControl•IEdit(LanczosData)FrequencyRange-LowerLimit0NumberofDesiredModes20Thisspecifiedfrequencyrangemeansthesolverwillcalculatethelowest-frequencymodeswithinthefirst20modesstartingfromthefrequencyof0.Ifyouincreasethenumberofdesiredmodes,youcanachieveamoreaccuraterepresentationofthestructure,butattheexpenseofsolutiontime.Youshouldincludeenoughmodestocoverthefrequencyrangeofinterest(basedonyourparticularmechanicalsystem).okRealEigenvalue-LanczosdialogboxCautionAcceptthedefaultsettingsforFlexibleBodySolutionTypeandFlexibleBodyExportOptions.TheseoptionsareintendedformanualintegrationwithRecurDynorAdamssoftwarepackages,andshouldnotbechangedforNXMotionSimulation.Ifyouchangethesedefaultsettings,theMotionSimulationflexiblebodysolutionmaynotsolve.OKOKConnecttheflexiblebodyFEMtothemechanismYoumustdefinethepointswheretheflexiblebodyisconnectedtootherdegreesoffreedominthemotionmechanism.Althoughyoucanuseanyelement

typetoconnecttheflexiblebody,typicallyyouwillusea1DConnection(spiderelement).—^SimulationNavigatorSimulationFileViewNoteIftheSimulationFileViewisnotvisible,clickthe(>)|1IbaratthebottomoftheSimulationNavigatortoopenit.demo_assy_fem1p•丄團TheFEMfileisdisplayedinthegraphicswindow,andislistedatthetopoftheSimulationNavigatorp•丄團StaticWireframe(Viewtoolbar,RenderingStyleDrop-downlist)1DConnection(AdvancedSimulationtoolbar,ConnectionsDrop-downlist)TypePointtoFaceTypePointtoFace-(SelectPoint)TypeBetweenTwoPointsTypeBetweenTwoPointsArc/Ellipse/SphereCenter(SpecifyPoint1andSpecifyPoint2)••ApplyApplyNoteSelectthearccentersofthetopandbottomedges.OKPointdialogboxtheface)NoteSelectthearccentersofthetopandbottomedges.OKPointdialogboxtheface)ConnectionElementRBE2Type

RBE2Thiscreatesaconnectionrecip.eInalaterstepinthisactivity,whenyoucreateasolidmeshonthepart,theconnectionrecipewillgenerateaspiderelementusingnodesdefinedinthegeometrymesh.RepeattheabovestepstocreatePointtoFaceRBE2connectionrecipesontheothertwoendsofthearm,asshowninthefollowingpictures.Whenyouarefinished,closethe1DConnectiondialogbox.7.MeshthepartNowcreateatetrahedralmeshonthesolidbody.

ShadedwithEdges(Viewtoolbar,RenderingStyleDrop-downlist)Drop-downlist)'3DTetrahedralMesh(AdvancedSimulationtoolbar,MeshDrop-downlist)■thepartTypeCTETRA(10)MeshParametersElementSize0.3•Thiselementsizeresultsinthreelayersofelementsthroughthethicknessintheregionswherebendingispredicted.Atleastthreelayersofsolidelementsareneededtoaccuratelymodelbending.OKThepartismeshedwithtetrahedralsolidelementsandtheconnectionrecipesarenow1Dspiderelements.

8.CreateanodegroupLaterinthisactivity,youwillneedtodefinestiffnessatthenodeatthecenterofeachofthethree1Dconnectionsyoucreatedpreviously.Tomakethatstepeasier,youwilladdthesenodestoanodegroup.__SimulationNavigator■-■GroupsewGroupNodeLabels•Becauseyoucreatedtheconnectionrecipesbeforeyoumeshedthepart,thecorenodesoftheresulting1Dconnectionsarelabeled1,2,and3.Youwilladdthesenodestothegroupbyenteringtheirlabels.Labels1,2,3•[~SelectMaterialsAluminum_2014上VNameconnectionnodesOKDefinematerialproperties—^SimulationNavigator11+3DCollectors(expand)lid(1)Edit仝EditNameconnectionnodesOKDefinematerialproperties—^SimulationNavigator11+3DCollectors(expand)lid(1)Edit仝Edit(SolidProperty)Properties□choosematerialOKalldialogboxesDisplaytheSimulationfile—^SimulationNavigatorSimulationFileView•53_demo_assy_sim1DefineconnectiondegreesoffreedomOKOKOKOKInapreviousstep,youcreatedspiderelementsatthethreeendsofthesuspensionarm.Theindependentnodeatthecenterofeachspiderelementwasdefinedtobecoincidentwiththeoriginpointofajointorbushingthatconnectsthiscomponenttothemechanism.YouwillnowdefinethelocalstiffnessattheseconnectionpointsusingaFixedBoundaryDegreesofFreedomconstraint.aticWireframe(Viewtoolbar,aticWireframe(Viewtoolbar,RenderingStyleDrop-downlist)FixedBoundaryDegreesofFreedom(FixedBoundaryDegreesofFreedom(AdvancedSimulationtoolbar,ConstraintTypelistConstraintTypelist)ModelObjectsGroupReferenceGroupReference(group_demo_assy_fem2::connection_nodesvlist)NoteThisisthenodegroupyoucreatedinthepreviousstep.DegreesofFreedom••Toensurethecorrectlocalstiffnessattheconnectionpoints,alwayssetallDOFtoOnwhencreatingFixedBoundaryDegreesofFreedomorFreeBoundaryDegreesofFreedomconstraintsinaflexiblebodyanalysis.Whenyoucreatedtheconnectionrecipeforeachspiderelement,youplacedtheindependentnodeattheborecenteroftheholeratherthanatthearccenteroftheedgeofthehole.Thisplacementensuresbalancedloading.SaveSave(Standardtoolbar)12.SolvethemodelYouwillsolvethemodeltogeneratethe.rfifilethatcontainsthereducedmatricesthatrepresentthecomponent'sdynamicbehavior.ThisfilewillbeusedlaterintheactivitywhenyousolvetheFlexibleBodysolutioninMotionSimulation.___SimulationNavigator(mainview)-Solution1OKYoucanignoretheInformationwindowwarningconcerningrigidlinks.TheAnalysisJobMonitordialogboxappears.

Waitforthejobtofinishandforthecommandwindowtoclose.Thisprocessmaytakeseveralminutes.CloseSolutionMonitordialogboxCancelAnalysisJobMonitordialogbox•Informationwindow•Informationwindow■Solution1••Intheexplorerwindowthatopens,notethelocationofthe.rfifile.Itshouldbelocatedinthef1_car_flex_bodyfolder,andshouldbenamedsimilarto_demo_assy_sim1solution_1_0.rfi.13.Viewthemodeshapes__LSimulationNavigatorPostProcessingNavigator-DSolution1(expand)Thefirstsixmodesarerigidbodymodes.Mode7(expand)BMode7(expand)B+Displacement-Nodal(expand)MagnitudeNoteTheendsofthepartoverlapbecauseofthedefaultdeformationscale,whichissetto10%ofthemodel.YoucanreducethescalingusingEditPostViewPostViewUsetheNextMode/Iterationcommandtoviewadditionalmodes.UsetheNextMode/Iterationcommandtoviewadditionalmodes.NextMode/Iteration(PostProcessingtoolbar)aReturntoModel(LayoutManagertoolbar)Save(Save(Standardtoolbar)Inalateractivity,youwillconnecttheflexiblebodytoamotionmechanism.IfyouplantocompletethenextFlexibleBodyactivity,leavethissimulationfileopeninNX.Youcompletedtheactivity.Flexiblebodyanalysis—MotionSimulationtasks1OpentheMotionSimulationIfyoucompletedthestepsinthepreviousFlexibleBodyactivityandyour_demo_assy_sim1.simpartisstillopeninNX,usethesesteps.Ifthepartisnotstillopen,orifyoudidnotcompletethepreviousFlexibleBodyactivity,skiptothenextpage.SimulationNavigatorSimulationFileView•巴_demo_assy•akeDisplayedPart•akeDisplayedPartThiscommandchangestheworkpartfromthesimulationfiletothemastermodelassembly.Start—MotionSimulationMotionNavigatorMotionNavigatormotion_1Skipthenextpageandmoveontopage3.2OpentheMotionSimulationUsethesestepsifthe_demo_assy_sim1.simpartwasnotstillopenfromthepreviousFlexibleBodyactivity.

pen(Standardtoolbar)Lookinf1_car_flex_body\_demo_assyV•FilesoftypeSimulationFiles(*.sim)y•Filenamemotion_1.simVOK••ThemotionsimulationopensintheMotionSimulationapplication.3.ResetthedialogboxsettingsTheoptionsyouselectinNXdialogboxesarepreservedforthenexttimeyouopenthesamedialogboxwithinanNXsession.Toensurethatthedialogboxesareintheexpectedinitialstateforeachstep-by-stepactivity,youshouldrestorethedefaultsettings.Preferences—UserInterfaceResetDialogBoxSettingsOKEnabletheFlexibleBodyDynamicsenvironment

TheFlexibleBodyDynamicsenvironmentisavailableonlywiththeDynamicsanalysistype.Environment(Motiontoolbar)FlexibleBodyDynamicsFlexibleBodyDynamicsOKDefinetheflexiblelinkBONoteYoucanselectanypartoftheindicatedlink.FlexibleModel••巴_demo_assy_sim1solution_1_0・fiThisisthe.rfifilegeneratedfromtheNXNastransolveinthepreviousFlexibleBodyactivity.Itshouldbelocatedinthef1_car_flex_bodyfolderalongwiththeFEMandSimulationfilesyoucreatedinAdvancedSimulation.NoteIfyoudidnotcompletethepreviousFlexibleBodyactivity,copytheprovidedSimulationfile,named_demo_assy_sim1・sim,fromthecompleted_sim_femsubfolderforthisactivitytothef1_car_flex_bodyfolder,andopenthefileinAdvancedSimulation.Then,intheSimulationNavigator,right-clickSolution1andselectSolvetogeneratethe.rfifile.OKRFIFiledialogboxLeavetheFlexibleLinkdialogboxopenforthenextstep.FinishdefiningtheflexiblelinkTheFlexibleLinkdialogboxisstillopenfromthepreviousstep.•TheFlexibleLinkPreviewwindowshowsyouthemeshedflexiblebodyanditsorientationrelativetotheabsolutecoordinatesystem.PlacementAbsoluteOriginBecausetheflexiblebodyisinthesameorientationasthecorrespondinglinkinthemechanism(relativetotheabsolutecoordinatesystem),AbsoluteOriginistheappropriateselection.TipYoucanpressandholdthemiddlemousebuttonintheFlexibleLinkPreviewwindowtorotatethepreviewedmodel,forvisualizationpurposes.•Connections•Thethreemarkersinthelistcorrespondtotheoriginsofthetwobushingsandsphericaljointdefinedonthislinkinthemechanism.

VerifythatthethreemarkersaremappedtotheconnectionnodesthatyoudefinedinAdvancedSimulation,inthepreviousFlexibleBodyactivity.Ifyoufollowedthemeshingstepsasspecifiedintheactivity,theconnectionnodesshouldbelabeledwithnodeIDs1,2,and3,andthenodeIDsshouldbemappedtothefollowingmarkers:oball_jt4.i_markeroG001.i_markeroG002.i_markerIfthemarkersarenotmappedtothecorrectnodes,youcanenterthecorrectnodeIDsdirectlyintheNodeIDcell(simplyclickinthecellandtypetheIDnumber).okFlexibleLinkdialogboxCreateaFlexibleBodysolutionMotionNavigatorMotionNavigator•巴motion1•TimeSolutionTypeAnalysisType•TimeSolutionTypeAnalysisTypeThismeansthesimulationwillrunforahalfsecond.Steps100•Thismeansthesimulationwillbedividedinto100stepsoverthehalf-secondsimulationduration.OK&AddtheflexiblelinktothesolutionMotionNavigatorMotionNavigator□FlexibleLinksBfore_lca-_demo_assy_sim1solution_1<^AddtoSolutionModeShapeDetailsViewNoteIftheModeShapeDetailsViewisnotvisible,clickthel<1jO,■[>l|1llbaratthebottomoftheMotionNavigatortoopenit.Thisviewpaneldisplaysthedynamiccharacteristics(frequency,mass,damping,andstiffness)foreachmode.Modeswithanasteriskcharacter(*)inthe#Modecolumnareconsideredactiveandareincludedintheanalysis.Bydefault,allmodesfromtheNXNastranmodalsolutionareincludedinthemotionsimulationexceptthefirstsixmodes,whichareconsideredrigidbodymodes.Includingallflexiblemodesensuresthemostaccuraterepresentationofthestructure.Ifyourmotionsimulationsolvesveryslowly,youcanfurtherreducethemodalmodelbyright-clickingmodesthatareinsignificanttoyouranalysisandchoosingDeactivate.Inthisactivity,youwillnotdeactivateanymodes.9.AddviscousdampingYouwilladdviscousdampingtothenormalmodes.MotionNavigatorMotionNavigator•MotionNavigator•MotionNavigator4.0%Viscous4.0OKModeShapeDetailsView■-■holdthemouseoveranyofthecolumnheaderslumnsfDampedFrequency(makesureDampedFrequencyisselected)ComparethevaluesintheFrequencycolumntothevaluesintheDampedFrequencycolumnthatyoujustadded.ModeShapeDetaiIsView#ModeFrequencyDampedFrequency%Viscous%Hysteretic*76145e□DriverContainer(expand)□DriverContainer(expand)'■Drv001<^AddtoSolutionThisdisplacementmotiondriver,whichisassignedtothesliderjointinthe6.140e+OQ1400000DDODDO9.553e+Q019.E45e+G014000