ADAMS中有限元介绍fe-part

1WelcometotheFEPartWelcometotheFEPartFEPartIntroduction2IntroductionTheFEPartisawhollyAdams-nativemodelingobjectwithinertiapropertiesandisaccurateforverylargedeformationcases(thatis,geometricnonlinearity)ofbeam-likestructures.TheFEPartdiffersfromthelinearflexiblebodyoptionwithinAdams/Flexintwosignificantways:1)ithastheabilitytoaccuratelyrepresentlargedeformationswhichthelinearmodesapproachcannotand2)itsmodelingdoesnotrequireanFEA-producedfilelikethemodalneutralfile(MNF).TheFEPartalsodiffersfromthebeamforceelementinthatitpossessesinertiaproperties.Theinertiapropertiesarespecifiedusingsymmetric,consistentmassmatrixwhichremainsconstant.ForamoredetailedcomparisonwithothermethodsofmodelinggeometricnonlinearitywithinAdamsclickhere.TheFEParthasbelowformulationoptions:•3DBeam:Athree-dimensionalfullygeometricallynonlinearrepresentationusefulforbeam-likestructures.Accountsforstretching,shearing,bending,andtorsion.•2DBeam(XY,YZ,orZX):Atwo-dimensionalgeometricallynonlinearrepresentationusefulforbeam-likestructureswherebythecenterlineofthebeamcanbeassumedconstrainedtoaplaneparalleltothemodel'sglobalXY,YZorZXplane.The2DBeamcanstretchorbendinplane.The2DBeamwillsolvefasterthanthe3DBeam.TheseformulationoptionsarebasedonanMSC-authoredadaptationofAbsoluteNodalCoordinateFormulation(ANCF).TheAdamsFEPartimplementationdiffersfrompureANCFprimarilyinthatitismorelikeahybridbetweenANCFandgeometricallyexactbeamtheorytoovercomethelimitationsoftheconventionalANCFformulation.Inthisway,thenewformulationdoesn'tsufferfromthenotoriousshearlockingphenomena.ThenameFEPartisappropriateforthisentitysincethisformulationisrootedinfiniteelementmodelinganditsimplementationwithinAdamssharesthefiniteelementmodelingconceptofnodes(seebelow).TheFEPartdoesnotsupportmaterialnonlinearity.Also,currentlytheFEPartisrecommendedtobeappliedonlytomodelingbeam-likestructures.Othershapeslikeplates/shellsorsolidsarenotcurrentlydirectlysupported.SystemlinearmodesanalysisviaAdams/LinearisnotcurrentlysupportedformodelsincludingFEPartsnorareAdams2NastranexportsoranalysesusingAdams/Controls.Note:FE_PARTcontactwithhollowsectionsisnotsupported.•ThereisnoproblemifthegeometrybelongstoaanyotherPARTorFLEX_BODY,onlyifthegeometrybelongstoanFE_PARTandthereiscontactonthatFE_PARTthenwedonotsupportit.3WelcometotheFEPartBuildingFEPartsBuildingFEPartsTheFE_Partiscomposedofsmallpieces,knownasfiniteelements.Thebehaviorofeachelementiswellknownunderallpossiblesupportandloadscenarios.Theelementssharecommonpointscallednodes,sectionpropertiesareassignedoneachnode.ThebasicbuildingblockstocreateFE_Partaredescribedbelow:•Material-Definesacollectionofconstantsneededtodefinethestress-strainrelationshipforagivenphysicalmaterial.Currently,onlyelasticbehaviorissupported.Thenumberofconstantsvariesdependingonwhetherthematerialisisotropic,orthotropic,oranisotropic.•Nodes-Definetheneutralaxisofthebeam,whoseaxispassesthroughtheoriginofeachnode.Allnodesmustbeorientedsuchthatthepositivex-axisistangenttotheneutralaxisofthebeamcentroid.Tothisend,weneedtospecifythelocationandorientationofthenodewithrespecttotheBCSoftheelement.Also,thenumberofnodesused,n,determinesthenumberofdegreesoffreedom(DOF)oftheFEPartassuch:DOFfor3DBeam:=3*((4*number_of_nodes)-1),DOFof2DBeams:=4*(number_of_nodes).WithinAdams/Viewthesenodesareobjectswithnames(typicalofotherAdams/Viewobjects)andlabelswhicharesinglepositiveintegeridentifierspassedtoAdams/Solver.ThemodelingautomationprovidedbytheFEPartcreateandmodifywizardinAdams/Viewwillnameandlabelnodesinaconsistentfashion,butusersmayrenameFENodes.•SectionProperties-Definethecross-sectionalpropertyvaluesforeachnodespecifyingareaandareamomentsofinertia(Iyy,Izz,IyzandJxx)ofthebeam.InteractingwithAdamsModelingElementsTheFEPartinteractswiththerestoftheAdamsmodelsimilartootherbodytypesinAdams.•Markers-MarkersonFEPartsmustbeassociatedwithasinglenode.Themarkerneednotnecessarilybecoincidentwithanode.Adams/Solverwillcomputetheinitialoffsettothenodeanditwillkeeptheoffsetinsubsequentcomputations.Themarkerwillmoveasifitisrigidlyattachedtoitsnode.WithinAdams/ViewanFEPartmarkercanbedefinedaseitherlocation-basedornode-based.Duringpre-processing,thelocationbasedmarkerwillalwaysremainatthespecifiedlocationandautomaticallyassociateitselfwiththenearestnodeevenafterre-meshingtheFEPart.•Thenode-basedmarkerwillalwaysremainassociatedwiththespecifiednodeevenifitisnotthenearestnode.MarkersautomaticallygeneratedonFEPartsbyAdams/View,forexamplewheninteractivelycreatingaconstraintorforce,willbelocation-based.•TheFEPartdoesnotsupportafloatingmarkers.So,anFEPartcannotbethereactionbodyforatorquevector(VTORQUE),forcevector(VFORCE),generalforce(GFORCE),curve-curveconstraint(CVCV)orpoint-curveconstraint(PTCV).•Constraints-Throughmarkers,thefullsuiteofAdamsconstraints(forexample,joints,jointprimitives,andmotions)canbeappliedtoanFEPart.FEPartBuildingFEParts4•AppliedForces-Throughmarkers,thefullsuiteofAdamspointforces(forexample,singlecomponentandmulti-componentforcesandtorques)canbeappliedtoanFEPart.TheFEPartdoesnotcurrentlysu