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1/75Gambit2.2Tips&TricksThomasScheideggerJune8,20042/75Outline•DataexchangewithotherCADsystems•Constructionandclean-uptools•Meshingtools•Miscellaneoustipsandtricks3/75DataexchangewithotherCADSystems•CADdataimport•Checkingconnectivity•Checkingrealgeometry/topology•Tolerantmodeling•Healingandsmoothingrealgeometry•Dataexchangeviameshimport4/75Geometry(Real/Virtual)CADDataImportGeometryMeshFacetedGeometry•ACIS(R12)•Parasolid(v15.0)•CatiaV4•STEP(AP203/214)•IGES•DirectPro/EInterface•I-DEASFTL•STL•VRML•Optegravisualizer•I-DEASUNV•FLUENT/TGRID•CGNS(v2.0)•PLOT3D(formatted)•ANSYS•PATRAN•NASTRANGeometry(Faceted)Geometry(Faceted)NewInterOPR12translatorsforIGES,STEP,Parasolid,andCatia4(add-on)inGambit2.2–Warningisissuedifthemodelsizeexceeds10000units5/75CheckingConnectivity•Checkimportofvolumes/facesusingentitybasedcoloring–Vertices(white),edges(yellow),faces(lightblue),volumes(green),groups(darkgreen)–Virtual/facetedgeometryidentifiedbylabel(v_*/f_*),pickingfilter,andcolorcoding•Vertices(darkkhaki),edges(peru),faces(dodgerblue),volumes(springgreen)•Checkconnectivityusingconnectivitybasedcoloring–White:Stand-alonevertexoredge–Orange:Vertexconnectedtoonlyoneedge,oredgeconnectedtoonlyoneface(i.e.unconnectedface!)–Blue:Vertexconnectedtoexactlytwoedges,oredgeconnectedtoexactlytwofaces(i.e.connectedface)–Magenta:Vertexconnectedtothreeormoreedges,oredgeconnectedtothreeormorefaces(e.g.internalface)6/75CheckingConnectivityColorbyentityColorbyconnectivity7/75CheckingRealGeometry/Topology•Checksforgeometricalandtopologicalinconsistencies–Topologyproblems(veryrare)mustbefixedbeforemeshing–Detailedreportingthroughchangeindefaults•GEOMETRY.GENERAL.REAL_GEOMETRY_CHECK_SUMMARY=0–GeometrynotC1orG1•Indicateslackofparametric/geometriccontinuity•Realoperations(booleans,splits,sweeps)mayfail•Canusevirtualoperationsasfallback•Geometryerrorsdogenerallynotpreventmeshing.Ifthemodelcanbeshaded,thenitcanlikelybemeshed•Howtofixproblems–Fixrealgeometryproblemsbyhealingtheunconnectedentities,smoothing(newinGambit2.2),orbyregeneratingentities–Fixtopologyproblemsbydeletingandreconstructingentities–Fixvirtual/facetedgeometryproblemsbydeleting(hiding)andreconstructingentities8/75TolerantModeling•TolerantmodelinginGambit–Realconnectivityusinganautomaticallyevaluatedlocaltolerancevalue(insteadof1.0e-6realACIStolerance)assignedtoverticesandedges–AllowsuseoflesspreciseCADdataandstillensurespropertopology–Mostconstructiontools(Booleansandsplits)aretolerant–Requireslessvirtualclean-up–Tolerantmodelingwillattempttostitchvolume–Makegeometrytolerant•globallyduringgeometryimport–allentitiescanbeconnected–Automaticsliver/shortedgeremovalduringtolerantimport,controlledthroughdefaultsGEOMETRY.TOLERANCE.HEAL_REMOVE_SLIVER_FACE=-1GEOMETRY.TOLERANCE.HEAL_REMOVE_SHORT_EDGE=0.001Printoutofentitylabelsbeingeliminated•controlledinsidehealface/volumeforms–allentitiesneedtobedisconnectedbeforemakingtolerant9/75•Assignslocaltolerancesinsteadofgeometrymodification•Tolerancesbasedonfacesizeoredgelength(bodyboxsize).StitchingstopsatmaximumtoleranceBodyboxsizeMaximumtolerance0.010.00010.10.0011.00.0110.00.110.01.0TolerantModelingTolerantIGESimport10/75HealingRealGeometry•ACISisahighprecisionmodelerandneedsallentitiestosatisfystringentdataintegritycheck•GeometryimportedfromotherCADsystemsoftenlackstherequiredaccuracy•HealingisanoperationdesignedtodetectandcorrectaccuracyproblemsinACISmodels•Optionalhealingprocesses–Geometrysimplification•Splinetoanalyticgeometryconversion–Stitchfaces–Repairgeometry•Healsinaccuraciesinmodel•Healingalwaysincludestolerantmodeling•Autoormanualtolerances11/75HealingRealGeometryStitchfacesStitchfaces,RepairgeometryEffectivetooltoconnect(stitch)facesintoavolumeFacehealingcanresultinmultiplevolumes12/75HealingRealGeometry•Healmodel–globallyduringgeometryimport•allentitiescanbeconnected•nocontroloverhealoptions–controlledinsidehealface/volumeforms•allentitiesneedtobedisconnectedbeforehealing•manualcontroloverhealoptionsandtolerances•ofteneasiertoexportACISmodelandhealgloballyduringre-import•Healingrepairsgeometrynearboundaries.Healingdoesnotfixgeometrydefectsdistantfromedges•Healingcanfurthercorruptpoorgeometry.Carefullyinspectandcheckgeometryafterhealing!13/75SmoothingRealGeometry•Geometry(edge,face)smoothinginGambit2.2–Smoothesdiscontinuousedges–ReducesgeometrydiscontinuitydefectsforB-splinesurfaces–CanaidinsubsequentBooleanoperations–Twosmoothingoptions•Removediscontinuities–RemoveG1discontinuity(default)•Reducecomplexity–SimplifiedNURBrepresentationFacesmoothing14/75DataExchangeviaMeshImport•Importofsurfaceorvolumemeshfilesresultsinfacetedgeometry,similartovirtualgeometry–Usevirtualgeometryoperationstoworkwithentities–Convertvirtualgeometrytorealifneeded•Effectivemethodto‘clean’corruptmeshablegeometry–MeshthedefectgeometryinGambitwithsufficientlyfinespacing–Assignboundaryzonestofacesasnecessary,exportmesh–ImportmeshbackintoGambitandworkwithfacetedgeometry•BoundarytypesarepreservedduringimportofmeshfilesintoGambit–Exceptperiodicboundarytypes,perio