R125ABAQUS资料CRSHW01BumperWord文件下载.docx

R125ABAQUS资料CRSHW01BumperWord文件下载.docx

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∙Examineinitialoverclosures

∙Definevariablemassscaling

∙Definecontactoutput

∙ViewsimulationresultsusingAbaqus/Viewer

Introduction

Thepurposeofabumpertestistopreventdamageandreducerepaircostsafterlow-speedimpactsliketheonesthatoccursooftenincommutertrafficandparkinglots.Thebumpertestisalsousedtoevaluatetheoverallenergyabsorptioncapabilitiesofthebumperstructure.Typicaltestsincludecrashingthefrontbumperintoaflatbarrier,therearbumperintoaflatbarrier,thefrontbumperintoanangledbarrier,andtherearbumperintoapole.

Thebumpermodelusedinthisworkshopisbasedonthepublic-domainDodgeCaravanmodelavailablefromtheFHWA/NHTSANationalCrashAnalysisCenter（NCAC）website（http:

//www.ncac.gwu.edu）.ThismodelhasbeentranslatedtoAbaqusandthebumpercomponentshavebeenextractedfromthefullvehiclemodel.

Themodelusesshellelementsformostofthecomponents,andsolidelementsforthebumperfoam.Thewalliscompletelyconstrainedandmodeledasrigid.Therestofthevehicleisalsomodeledasarigidbody.Thevehiclemassandrotaryinertiaarelumpedattherigidbodyreferencenode;

thenodeisplacedatthevehicle’scenterofmass.Theendnodesofthebumperrailsareincludedintherigidbodydefinitionusingtienodes.

TheconnectionsbetweenvariouspartsofthemodelaremodeledusingbeamMPCs,althoughmeshindependentspotwelds,whichoffermoregeneralcapabilities,couldalsobeused.

Differenttypesofmaterialmodels,includingMisesplasticitywithisotropichardeningandcrushablefoamwithisotropichardening,arealsoincludedinthemodel.

Aninitialvelocityof7800mm/sisappliedtothevehiclerigidbodyreferencenode.

FigureW1–2Bumpermodelwithoutabumpercover.

Definingcontact

Inthissectionyouwilldefinecontactfortheentiremodelusingthegeneralcontactapproach.Apartiallycompletedinputfileisprovidedasastartingpoint.YouwillhavetoedittheinputfiletocompletetheAbaqusmodel.

1.Switchtothedirectory../crash/bumper.

2.Openthefilew_caravan_bumper_wall.inpinatexteditor.

3.Addan“all-exterior”contactdefinitionfortheentiremodel:

*CONTACT

*CONTACTINCLUSIONS,ALLEXTERIOR

NodatalinesarerequirediftheALLEXTERIORparameterisincluded.Bothoptionsmustbeaddedtothehistorydataofyourinputfile.

4.DefineasurfaceinteractionnamedFRICTION1.Specifyafrictioncoefficientof0.1.

*SURFACEINTERACTION,NAME=interactionname

*FRICTION

frictioncoefficient

5.AssignsurfaceinteractionFRICTION1tothedefault（i.e.,“ALLEXTERIOR”）contactdomain:

*CONTACTPROPERTYASSIGNMENT

,interactionname

Eachoftheemptyspacesreferstothedefaultunnamed,all-inclusive,element-basedsurfacedefinedautomaticallybyAbaqus/Explicit.Theoptionmustbeaddedtothehistorydataofyourinputfile.

6.OpentheonlineAbaqusdocumentation.Examinethemeaningofthe*CONTACTINCLUSIONSand*CONTACTPROPERTYASSIGNMENToptionsusingtheAbaqusKeywordsGuide,ifnecessary.

7.Saveallthechangesandclosetheinputfile.

Submittingadatacheckanalysis

Thetimerequiredtocompletecomplexsimulationsisoftenquitelong,soitisagoodpracticetoreviewthemodelcreatedandtocompleteadatacheckanalysispriortosubmittingtheanalysis,especiallyifthejobwillrunovernight.

8.Submitthejobforadatacheckanalysis:

abaqusdatacheckjob=w_caravan_bumper_wall

9.Openthedatafile（w_caravan_bumper_wall.dat）inatexteditor.

WhatversionofAbaqusareyouusing?

10.Inthedatafile,searchforthestrings“WARNING”and“ERROR”tofindanywarninganderrormessages.Thesemessageswillindicatewhetheranythingunusualwasencounteredduringthedatacheckanalysis（keepinmindthatyoureditormaybecase-sensitiveforsearching）.

11.SearchforthestringPROBLEMSIZEtoseethesummaryoftheproblemsize.Includespacesbetweenthelettersofthesearchstring.

12.Openthestatusfile（w_caravan_bumper_wall.sta）inatexteditor.

Whatistheinitialstabletimeincrementsizeforthismodel?

ModelvisualizationinAbaqus/Viewer

Duringadatacheckanalysis,Abaquscreatesanoutputdatabase（.odb）file.Whilethisoutputdatabasedoesnotcontainanyanalysisresults（adatacheckjobendsbeforetheanalysisisperformed）,itcanbeusedtocheckvariousaspectsofthemodeldefinition.Inthissectionyouwillviewinitialcontactoverclosuresandthedistributionoftheelementstabletimeincrements.Thesmallestelementstabletimeincrementwillbeusedastheinitialstabletimeincrementfortheanalysis.

13.Whenthejobcompletes,opentheoutputdatabasefileforthebumpercrashanalysisinAbaqus/Viewer:

abaqusviewerodb=w_caravan_bumper_wall

Note:

Thefilenameextension（.odb）isnotneeded.

WhenAbaqus/Vieweropenstheoutputdatabase,theundeformedmodelshapewillbedisplayed.Tochangetheplotstate,youcanuseeitherthePlotmenuorthetoolbox 

iconsdisplayedontheleftsideoftheviewport.Youcanidentifythefunctionofeachtoolinthetoolboxbypositioningyourcursorabovetheiconforthattool.Alabelfortheiconwillpopupdescribingitsfunction,asshownbelow:

14.Examinetheinitialoverclosuresinthemodelbyselectingthedisplacementresultantastheoutputvariable.

a.FromthelistofvariabletypesontheleftsideoftheFieldOutputtoolbar,selectSymbol.

b.Fromthelistofprimaryvariablesinthecenterofthetoolbar,selectSTRAINFREE.

Bydefault,thearrowsarecolor-codedtocorrespondtoalegendindicatingtheirmagnitude.Thismaymakeitdifficulttoseethearrows.Touseasinglecolorforallarrows,click

inthetoolboxandselectUniformasthecoloroption.

TheplotappearsasshowninFigureW1–3.

FigureW1–3Symbolplotofinitialoverclosures.

15.Examinethedistributionoftheelementstabletimeincrements.

a.FromthelistofvariabletypesontheleftsideoftheFieldOutputtoolbar,selectPrimary.

b.Fromthelistofprimaryvariablesinthecenterofthetoolbar,selectEDT.

TheplotappearsasshowninFigureW1–4.

Theminimumelementstabletimeincrementvalueinthecontourplot（8.636e-7）doesnotmatchtheinitialstabletimeincrementspecifiedinthestatusfile（8.534e-07）.ThisisduetotheaveragingoftheEDTvaluesatnodesinthecontourplot.Ifnodalaveragingisdeactivated（Result→Options）thecontourplotminimummatchestheinitialstabletimeincrementgiveninthestatusfile.

FigureW1–4ContourplotofelementinitialstabletimeincrementEDT.

Definingcomplexcontactconditions

Inthissectionyouwilldefinemorecomplexcontactconditionsfortheentiremodelusingcontactandsurfacepropertyassignments.Youwillalsodefinevariablemassscalingandacontacthistoryoutputrequesttocompletethemodel.Continueworkingwiththeinputfilefromtheprevioussectionofthisworkshop.

16.DefineanewsurfaceinteractionnamedFRICTION2.Specifyafrictioncoefficientof0.2.

17.DefineanothersurfaceinteractionnamedFRICTION3.Specifyafrictioncoefficientof0.3.

18.Modifytheexisting*CONTACTPROPERTYASSIGNMENToption.AssignFRICTION3tothecontactinteractionbetweenthe“default”surfaceandthesurfacenamedRIGID_BARRIER-1.RIGID_BARRIER_SURFACE.Similarly,assignFRICTION2tothecontactinteractionbetweenthesurfacenamedBUMPER-1.BUMPER_FOAM_SKIN_SURFACEandthesurfacenamedBUMPER-1.BUMPER_COVER_SURFACE.

,FRICTION1

surfacename,FRICTION3

surfacenamea,surfacenameb,FRICTION2

19.Assignsurfaceproperties.SetPROPERTY=THICKNESSonthe*SURFACEPROPERTYASSIGNMENToptiontoassignthesurfacethicknesstodefaultsurface（firstitemonthedataline）.Setthescalingfactorforthissurfaceequalto0.65.Scalingthesurfacethicknessinthiswayreducestheinitialoverclosuresinthismodel.

*SURFACEPROPERTYASSIGNMENT,PROPERTY=propertytype

ORIGINAL,scalingfactor

20.Definevariablemassscaling.Massscalingprovidesasimplemeanstomodifythemassesofafewsmallelementsinadynamicmodelsotheydonotcontrolthestabletimeincrementsize.UsetheparameterTYPE=BELOWMINtoscalethemassesofonlythoseelementswhosestabletimeincrementislessthanthevalueassignedtotheDTparameter;

settheDTparameterequalto1.5E-6:

*VARIABLEMASSSCALING,TYPE=BELOWMIN,DT=dt,FREQUENCY=5

Whenyoucompletethisanalysis,youshouldopenthestatusfileandcheckthemasschangeinthemodel.Massscalinginadynamicanalysisshouldnotsignificantlychangetheamountofmassinamodel.Inthisanalysis,thepercentagechangeofmassintheentiremodelisabout0.02%.However,thepercentagechangeofmassforthebumperisabout3%.

21.DefineacontacthistoryoutputrequestforthesurfacenamedRIGID_BARRIER-1.RIGID_BARRIER_SURFACE.Forcedistributionsonthesurfaceduetogeneralcontactareusedtocalculatethesurfaceforceresultants.RequestoutputofthetotalforceduetocontactpressureCFN,thetotalforceduetofrictionalstressCFS,andthetotalforceduetobothcontactpressureandfrictionalstressCFT.Lateryouwillcomparetheseforceswiththereactionforcesattherigidbarrierreferencenode.

*CONTACTOUTPUT,SURFACE=surfacename

CFN,CFS,CFT

22.Examinethesectioncontrolsusedforthebumperfoaminthismodel（seeFigureW1–5）.TheDISTORTIONCONTROLparameteractivatesaconstraintthatactstopr