LS-DYNA复合材料建模教程

ModelingofCompositesinLS-DYNA,SomeCharacteristicsofCompositesOrthotropicMaterialCoordinateSystemUser-definedIntegrationRuleforShellsOutputforCompositesSomeCharacteristicsofSeveralCompositeMaterialModelsinLS-DYNAClosingRecommendations,TwoGeneralClassesofComposites,Advancedcompositeshavestiff,highstrengthfibersboundinamatrixmaterial.Eachlayer/lamina/plyisorthotropicbynatureasthefibersruninasingledirection.Usually,anadvancedcompositesectionwillhavemultiplelayersandeachlaminawithinthestackwillhavethefibersrunninginadifferentdirectionthanintheadjacentlamina.Asandwichcompositesectionhaslaminaewhichmaybeindividuallyisotropicbutthematerialpropertiesandthicknessmayvaryfromlaminatolamina.Afoamcorecompositeisaparticulartypeofsandwichcompositewhereathick,softlayeroffoamissandwichedbetweentwothin,stiffplies.,OrthotropicMaterialsinLS-DYNA,Orthotropicmaterialconstantsaredefinedinthematerialcoordinatesystem.Thematerialcoordinatesystemmustbeinitiallyestablishedforeachorthotropicelementand,inthecaseofshells,foreachthrough-thicknessintegrationpointaswell.Thisorientationcomesfromthreesources.Inthematerialdefinition(*mat)Seedescriptionof“AOPT”inUsersManualunder*mat_2(orthotropic_elastic)Inthesectiondefinition(*section_shell)A“beta”angleisgivenforeachintegrationpointOptionally,intheelementdefinition(*element_shell_beta,*element_solid_ortho),OrthotropicMaterialsinLS-DYNA,Asthesolutionprogressesandtheelementsrotateanddeform,thematerialcoordinatesystemisautomaticallyupdated,followingtherotationoftheelementcoordinatesystem.Theorientationofthematerialcoordinatesystemandthusresponseoforthotropicshellscanbeverysensitivetoin-planeshearingdeformationandhourglassdeformation,dependingonhowtheelementcoordinatesystemisestablished.Tominimizethissensitivity,“InvarientNodeNumbering”,invokedbysettingINN=2(shells)or3(solids)in*control_accuracyishighlyrecommended.,User-Defined(Through-Thickness)Integration,GaussianorLobattointegrationruleshavepre-establishedintegrationpointlocationsandweights(NIP=10).LobattoincludesintegrationpointsontheoutsidesurfacesTrapezoidalintegrationhasequallyspacedintegrationpoints.Forcomposites,theusermayneedtodefinehis/herownintegrationpointlocationsandweights(correspondingtoplythicknesses)andmayneedtoreferenceadifferentsetofmaterialconstantsforeachintegrationpoint.,User-DefinedIntegration(970),*PARTmaterial11111*PARTmaterial22112$-+-1-+-2-+-3-+-4-+-5-+-6-*SECTION_SHELL12-2018.00000018.00000018.00000018.000000*mat_layered_linear_plasticity11,2.7e-6,73.4,0.32,1e9*mat_layered_linear_plasticity12,6.3e-7,0.286,0.3,1e9*INTEGRATION_SHELL20,8,0-.9722,.02778,1-.9167,.02778,1-.6667,.22222,2-.2222,.22222,2.2222,.22222,2.6667,.22222,2.9167,.02778,1.9722,.02778,1*ELEMENT_SHELL1112333221233433,Negativevalueindicatesuserintegrationrule,User-DefinedIntegration(971),$no*sectioncommandneeded$thicknessissumofthickvaluesgivenin*PART_COMPOSITE$noneedformultiple*PARTcommands$*PART_COMPOSITE$pid,elform1,2$mid,thick,beta,mid,thick,beta11,0.5,11,0.512,4.0,12,4.012,4.0,12,4.011,0.5,11,0.5*mat_layered_linear_plasticity11,2.7e-6,73.4,0.32,1e9$NOTE:foamcorecoulduseadifferent$materialmodel(971)*mat_layered_linear_plasticity12,6.3e-7,0.286,0.3,1e9*ELEMENT_SHELL1112333221233433,OutputforComposites,Forcompositematerialmodels,stresses(andstrains)willbewritteninthematerialcoordinatesystemratherthantheglobalcoordinatesystemifCMPFLG(andSTRFLG)issetto1in*database_extent_binary.Usefuloptionforpostprocessingoffiberandmatrixstresses.SetMAXINTin*database_extent_binarytothetotalnumberofthrough-thicknessintegrationpointsinyourcompositeshell.Bydefault,stressesonlyatthetop,bottom,andmiddleintegrationpointsarewritten.,OutputforComposites,Somecompositematerialmodelshave“extrahistoryvariables”thathelptotrackmodesoffailureineachintegrationpoint.(SeematerialdocumentationintheUsersManualfordetails.)NEIPS(shells)orNEIPH(solids)in*database_extent_binaryshouldbesettothenumberofextrahistoryvariablesneeded.Forexample,ifyouwanttotrackthedamageparameter(6thextrahistoryvariable)inmat_054,setNEIPSto6.,CompositeMaterialModels,*mat_2(elastic_orthotropic)9elasticconstants(solids);6elasticconstants(shells).TotalLagrangianformulation(okayforlargeelasticdeformations).Nofailurecriteria.Eachofthefollowingorthotropicmaterialsofferaparticularbrandoffiber/matrixdamageandfailurecriteria.Upto5strengthvaluesaregiven(XT,XC,YT,YC,SC).*mat_22(composite_damage)*mat_54,55(enhanced_composite_damage)*mat_58(laminated_composite_fabric)*mat_158like58butincludesstrainrateeffects*mat_59(composite_failure(_shell,_solid)_model)Mats22and59canbeusedwithshellsandsolids,CompositeMaterialModels,ThepaperCrashworthinessAnalysiswithEnhancedCompositeMaterialModelsinLS-DYNA-MeritsandLimits,Schweizerhofetal,5thInternationalLS-DYNAUsersConference(1998)providessomeinsightintoseveralcompositematerialmodelsinLS-DYNA,includingmat_54,mat_58,andmat_59.Thispaper(inPDFformat)andotherfiles/examplesrelatedtocompositesareavailableinftp:/,ComparisonofSeveralCompositeMaterialModels,UniaxialTensioninFiberDirection,ComparisonofSeveralCompositeMaterialModels,UniaxialTensioninFiberDirection,XT,XT*SR,XT*SLIMT,E11T,DFAILT,ERODS,B,XT=fibertensilestrength,LaminatedShellTheory,UseofLaminatedShellTheory(LST)isimportantifacompositeshellhaslayersofdissimilarmaterials.LSTcorrectsfortheincorrectassumptionofuniformconstantshearstrainthroughthethicknessoftheshell.WithoutLST,asandwichcompositewillgenerallybemuchtoostiff.LAMSHT=1in*control_shellinvokesLSTformaterialmodels22,54,55,76*Mat_layered_linear_plasticity(114)isaplasticitymodelmuchlikemat_024butwhichincludesLST.,CompositeMaterialModels,*mat_116(composite_layup)Orthotropicelasticresultantformulation(nostressescalculated)VeryefficientforlargenumberoflayersRequires*integration_shellMaterialconstantscanvaryfromlayertolayerDoesNOTuselaminatedshelltheory(notgoodforfoamcore/sandwichcomposites),CompositeMaterialModels,*mat_117(composite_matrix)*mat_118(composite_direct)Resultantformulation(nostressescalculated)21coefficientsofsymmetricstiffnessmatrixareinputdirectlyStiffnesscoefficientsin117giveninmaterialcoordsystemStiffnesscoefficientsin118giveninelementcoordsystem(lessstoragereqd)Shellthicknessisinherentinstiffnessmatrix.Thusuniformthicknessofpartismandatory.,CompositeMaterialModels,*mat_161(composite_msc)ProprietarymodelfromMaterialsSciences(requireslicenseadd-on)AvailableforsolidsonlyOffersfibershearandfibercrushfailurecriteriaCanpredictdelamination*mat_162like*mat_161butadoptsdamagemechanicsapproachforsofteningafterdamageinitiation,AFewWordsaboutDelamination,Shellsaregenerallyplanestresselements(szz=0)andthusarenotwell-suitedtorigorousstudyofcompositedelamination.Version971hasthicknessstretchshellelements(ELFORMS25,26,27)whichDOincludeszz.ToosoontosayiftheseelementsaresuitablefordelaminationstudiesDelaminationbehaviormaybeapproximatedusingmultiplelayersofshells