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∙Avarietyofmeshcontrols,suchas:
∙Elementshape
∙Meshingtechnique
∙Meshingalgorithm
∙Adaptiveremeshingrule
∙AtoolforassigningAbaqus/StandardandAbaqus/Explicitelementtypestomeshelements.Theelementscanbelongeithertoamodelthatyoucreatedortoanorphanmesh.
∙Atoolforverifyingmeshquality.
∙Toolsforrefiningthemeshandforimprovingthemeshquality.
∙Atoolforsavingthemeshedassemblyorselectedpartinstancesasanorphanmeshpart
17.2
EnteringandexitingtheMeshmodule
YoucanentertheMeshmoduleatanytimeduringanAbaqus/CAEsessionbyclickingMeshintheModulelistlocatedinthecontextbar.UponenteringtheMeshmodule,theAbaqus/CAEinterfacechangesinthefollowingways:
∙TheSeed,Mesh,Feature,andToolsmenusappearonthemainmenubar.
TheObjectfieldthatappearsinthecontextbarallowsyoutodisplayeitherapartortheassembly.17.3.1
Themeshingprocess
Tocreateanacceptablemesh,youusethefollowingprocess:
Assignmeshattributesandsetmeshcontrols
TheMeshmoduleprovidesavarietyoftoolsthatallowyoutospecifydifferentmeshcharacteristics,suchasmeshdensity,elementshape,andelementtype.
Generatethemesh
TheMeshmoduleusesavarietyoftechniquestogeneratemeshes.Thedifferentmeshtechniquesprovideyouwithdifferentlevelsofcontroloverthemesh.
Refinethemesh
TheMeshmoduleprovidesavarietyoftoolsthatallowyoutorefinethemesh:
∙Theseedingtoolsallowyoutoadjustthemeshdensityinselectedregions.
∙ThePartitiontoolsetallowsyoutopartitioncomplexmodelsintosimplersubregions.
∙TheVirtualTopologytoolsetallowsyoutosimplifyyourmodelbycombiningsmallfacesandedgeswithadjacentfacesandedges.
∙TheEditMeshtoolsetallowsyoutomakeminoradjustmentstoyourmesh.
Optimizethemesh
Youcanassignremeshingrulestoregionsofyourmodel.Remeshingrulesenablesuccessiverefinementofyourmeshwhereeachrefinementisbasedontheresultsofananalysis.
Verifythemesh
Theverificationtoolsprovideyouwithinformationconcerningthequalityoftheelementsusedinamesh.
17.3.2
Meshattributesandcontrols
Abaqus/CAEprovidesyouwithavarietyoftoolsforcontrollingmeshcharacteristics:
∙Youcanspecifythedensityofameshbycreatingseedsalongtheedgesofthemodeltoindicatewherethecornernodesoftheelementsshouldbelocated.Forexample,Figure17–1displaysamodelwithbiasedseedingalongthetopandleftedges.
Figure17–1Amodelwithbiasedseeding.
Formoreinformation,see“Understandingseeding,”Section17.4.
∙Youcanselecttheshapeofthemeshelements.Forexample,Figure17–2showsamodelthathasbeenmeshedfirstwithquadrilateralelementsandthenwithtriangularelements.
Figure17–2Twomesheswithdifferentelementshapes.
Formoreinformation,see“AssigningAbaquselementtypes,”Section17.5.
∙Youcanchoosethemeshingtechnique—free,structured,orswept—and,whereapplicable,youcanchoosethemeshingalgorithm—medialaxisoradvancingfront.Formoreinformation,see“Meshgeneration,”Section17.3.3.
∙Youcanselecttheelementtypethatisassignedtothemeshbychoosingtheelementfamily,geometricorder,andshapealongwithspecificelementcontrols,suchashourglassing.Formoreinformation,see“Understandingmeshgeneration,”Section17.7.
Forinformationonrelatedtopics,clickanyofthefollowingitems:
∙“Understandingseeding,”Section17.4
∙“AssigningAbaquselementtypes,”Section17.5
∙“Verifyingandimprovingmeshes,”Section17.6
17.3.3
Meshgeneration
Abaqus/CAEcanuseavarietyofmeshingtechniquestomeshmodelsofdifferenttopologies.Insomecasesyoucanchoosethetechniqueusedtomeshamodelormodelregion.Inothercasesonlyonetechniqueisvalid.Thedifferentmeshingtechniquesprovidevaryinglevelsofautomationandusercontrol.TherearetwomeshingmethodologiesavailableinAbaqus/CAE:
top-downandbottom-up.
Top-downmeshinggeneratesameshbyworkingdownfromthegeometryofapartorregiontotheindividualmeshnodesandelements.Youcanusetop-downmeshingtechniquestomeshone-,two-,orthree-dimensionalgeometryusinganyavailableelementtype.Theresultingmeshexactlyconformstotheoriginalgeometry.Therigidconformancetogeometrymakestop-downmeshingpredominantlyanautomatedprocessbutmaymakeitdifficulttoproduceahigh-qualitymeshonregionswithcomplexshapes.
Bottom-upmeshinggeneratesameshbyworkingupfromtwo-dimensionalentities(geometricfaces,elementfaces,ortwo-dimensionalelements)tocreateathree-dimensionalmesh.Youcanusebottom-upmeshingtechniquestomeshonlysolidthree-dimensionalgeometryusingall—ornearlyall—hexahedralelements.Generatingameshusingthebottom-upmeshingtechniqueisamanualprocess,andtheresultingmeshmayvarysignificantlyfromtheoriginalgeometry.However,allowingthemeshtovaryfromgeometrymayallowyoutoproduceahighqualityhexahedralmeshonregionswithcomplexshapes.
∙“Top-downmeshing,”Section17.3.4
∙“Bottom-upmeshing,”Section17.3.5
∙
∙Abaqus/CAEmaychangethecolorofthepartinstancesintheassemblydisplayedintheviewport.Thesecolorcuesdescribethemeshabilityanddependenceofeachinstance.Independentinstancesappearinacolorthatdescribestheirmeshability,whiledependentintancesappearblueintheAssemblycontextandwhiteinthePartcontext.See“Meshingindependentanddependentpartinstances,”Section17.3.10.
Note:
PartinstancesarecolorcodedaccordingtotheirmeshabilityanddependenceonlywhentheMeshdefaultscolormappingisselected.Ifyoudisplayedthedefaultcolormappinginadifferentmodule,Abaqus/CAEappliestheMeshdefaultscolormappingautomaticallyuponyourentrytotheMeshmodule.Ifyouselectedanon-defaultcolormappingsuchasMaterialsinadifferentmodule,Abaqus/CAEcontinuescolorcodingaccordingtothatcolormapping(inthiscase,bymaterialtype)whenyouentertheMeshmodule.
ToexittheMeshmodule,selectanyothermodulefromtheModulelist.Youneednotsaveyourmeshbeforeexitingthemodule;
itwillbesavedautomaticallywhenyousavetheentiremodelbyselectingFile
SaveorFile
SaveAsfromthemainmenubar.
17.3.4
Top-downmeshing
Top-downmeshingreliesonthegeometryofaparttodefinetheouterboundsofthemesh.Thetop-downmeshmatchesthegeometry;
youmayneedtosimplifyand/orpartitioncomplexgeometrysothatAbaqus/CAErecognizesbasicshapesthatitcanusetogenerateahigh-qualitymesh.Insomecasestop-downmethodsmaynotallowyoutomeshportionsofacomplexpartwiththedesiredtypeofelements.Thetop-downtechniques—structured,swept,andfreemeshing—andtheirgeometryrequirementsarewell-defined,andloadsandboundaryconditionsappliedtoapartareassociatedautomaticallywiththeresultingmesh.
Structuredmeshing
Structuredmeshingisthetop-downtechniquethatgivesyouthemostcontroloveryourmeshbecauseitappliespreestablishedmeshpatternstoparticularmodeltopologies.Mostunpartitionedsolidmodelsaretoocomplextobemeshedusingpreestablishedmeshpatterns.However,youcanoftenpartitioncomplexmodelsintosimpleregionswithtopologiesforwhichstructuredmeshingpatternsexist.Figure17–3showsanexampleofastructuredmesh.Formoreinformation,see“Structuredmeshingandmappedmeshing,”Section17.8.
Figure17–3Astructuredmesh.
Sweptmeshing
Abaqus/CAEcreatessweptmeshesbyinternallygeneratingthemeshonanedgeorfaceandthensweepingthatmeshalongasweeppath.Theresultcanbeeitheratwo-dimensionalmeshcreatedfromanedgeorathree-dimensionalmeshcreatedfromaface.Likestructuredmeshing,sweptmeshingisatop-downtechniquelimitedtomodelswithspecifictopologiesandgeometries.Figure17–4showsanexampleofasweptmesh.Formoreinformation,see“Sweptmeshing,”Section17.9.
Figure17–4Asweptmesh.
Freemeshing
Thefreemeshingtechniqueisthemostflexibletop-downmeshingtechnique.Itusesnopreestablishedmeshpatternsandcanbeappliedtoalmostanymodelshape.However,freemeshingprovidesyouwiththeleastcontroloverthemeshsincethereisnowaytopredictthemeshpattern.Figure17–5showsanexampleofafreemesh.Formoreinformation,see“Freemeshing,”Section17.10.
Figure17–5Afreemeshgeneratedwithtetrahedralelements.
∙“Understandingmeshgeneration,”Section17.7
17.3.5
Bottom-upmeshing
Bottom-upmeshingusesthepartgeometryasaguidelinefortheouterboundsofthemesh,but