Running ABAQUS 6.9 (PDF Format) - Department of Engineering

18 Pages·2010·0.21 MB·English

CONTENTS CONTENTS
7 PostProcessingusingThirdPartyPrograms 32
7.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
7.2 PostProcessingusingPATRAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Running ABAQUS6.9
8 Troubleshooting 33
8.1 NoMessageFile. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
8.2 BlankpagesinsteadofPlotsforhardcopy . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
ArulMBritto
8.3 Bugs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
May7,2010 9 FAQandOtherInfo 33
9.1 On-lineDocumentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
9.1.1 Keywords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Contents 9.1.2 UserManual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
1 Introduction 2
1.1 Manuals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1.1 ABAQUS/StandardandExplicit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 Programs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 WheretoStart? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4 Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.5 SuggestedCourseofAction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 DataPreparation 6
2.1 Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2 ABAQUSInput . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.3.1 Exercise1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.3.2 Exercise2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.4 SimpleMeshGenerationCommands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3 RunningABAQUS 22
3.1 RunningBatchJobs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.2 RunningLargeJobs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.3 ABAQUSEnvironmentFile:abaqusv6.env. . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.4 CheckingforErrors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.5 KillinganABAQUSjob. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.6 CheckingtheLicenseServer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.7 RestartinganABAQUSRun . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4 FileextensionsusedbyABAQUS 25
5 PrintedOutput 25
6 RunningABAQUS/Viewer 27
6.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.2 MeshPlots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.3 DisplacementPlotsandGettingHardCopies . . . . . . . . . . . . . . . . . . . . . . . . . 28
6.4 ContourPlots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6.5 PATHPlots. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6.6 X-YPlots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.7 CreatingaForceDisplacementPlot. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.8 WritingOutResults. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
1 2
1 INTRODUCTION 1.2 Programs 1 INTRODUCTION
1 Introduction 1.2 Programs
ABAQUSisageneralpurposefiniteelementprogramdistributedbyABAQUSLtd. Ithasalarge ABAQUS/StandardandABAQUS/ExplicitarebothavailableintheCUEDteachingsystemcomput-
elementlibraryandiscapableofanalysisofavarietyofproblems(linear,nonlinear,static,dynamic, ers.ABAQUS/CAEisthepre-processorandABAQUS/Viewerinthepostprocessor.PATRANisan
structuralandthermal). ABAQUS/CAEisaninteractivegraphicalforrunningABAQUS.Postpro- establishedpre-andpost-processorforABAQUS.
cessingisprovidedbyaseparatemoduleknownastheViewer. ABAQUS/Designissuitableforparametricstudyandoptimisation.
Themainaimofthismanualisprovideanoverview. Itdoesnotprovideanyinstructionson
howtoruntheCAEmodule.Thishasbeencoveredextensivelyelsewhere.Howeveressentialuseof 1.3 WheretoStart?
ABAQUS/Vieweriscoveredbutbynomeanscomprehensive.
Theremainderofthissectiondealswiththemanuals,thecommandstorunthevariousmodules Figure1showstheinter-relationshipbetweentheABAQUSAnalysismoduleandthepreandpost-
andhowtogoaboutrunninganABAQUSanalysisintheCambridgeUniversityEngineeringDepart- processormodules(CAEandViewer).
ment’sTeachingSystem(T.S.)Computers.
• IfyouwanttomakeastartusingABAQUSwiththeminimumamountofreadingtogetfamil-
Section2ofthismanualdealswiththeinputtotheABAQUSAnalysismodule. Section3sum-
iarisedwithrunningsimpleproblemsthenstartwiththeABAQUS/CAEUser’smanualAp-
marisesthesystemdependentcommandsnecessarytorunABAQUSintheTeachingSystem.Section
pendixBtutorialofAloadedcantileverbeam.Thistakesonethroughpre-processing,analysis
4liststhevariousfilescreatedduringanABAQUSrun. Section5summarisestheprintedoutput.
andpostprocessingfromwithinthegraphicalinterfaceABAQUS/CAE.AppendixDcovers
Section6dealswiththepostprocessingfacilitiesavailablewithABAQUS.Section7dealswithpost-
outputpostprocessingaspects. InChapter4thereisafurthertutorialdealingwithadvanced
processingusingthePATRANprogram.Section8dealswithhowtotroubleshootwhenyouencounter
techniques?
problems.Section9coversfurtherinformationonadditionalmanuals,examplesandABAQUSFAQ’s.
ThishandoutismainlyaimedatABAQUS/Standardusers.Thereisnoequivalenthandoutforthe • IfyouwanttofamiliariseyourselfwiththestructureoftheABAQUSinputdatathenwork
ABAQUS/Explicitprogram.ABAQUS/Explicitusersshouldconsulttherelevantusermanuals. throughtheexamplegiveninthishandoutandtryrunningtheexample(sections2and3)and
thencompletethepostprocessing(section6).Thenifyouhavetomakechangestotheinputdata
1.1 Manuals youwillhavesomeideaofthestructure/layoutofaninputfile.Thenyoucanworkthroughthe
tutorialsmentionedabove.Thenfollowthesuggestedcourseofaction,incarryingoutyourown
AsetofthemanualsisavailableforreferenceintheComputerOperator’sOffice.Notallthemanuals analysis.
areavailableinpaperform.Somemanualsareonlyavailableon-line(Example:Theory,Verification
...).SeealsotheUsingABAQUSOn-linedocumentation.
Theon-lineversionofthedocumnetationisquitecomprehensiveandup-to-date. 1.4 Commands
1.1.1 ABAQUS/StandardandExplicit TofindoutaboutalltheoptionsthatareavailablewithABAQUSandthiswilllistalltheoptionsthat
canbeusedwhenrunningABAQUS.
1. ABAQUS/CAEUser’sManual abaqushelp
Seealsosections3.1.1,3.2.1to3.2.27oftheABAQUSUser’smanual(Volume1)formoreinforma-
2. GettingStartedwithABAQUSInteractiveEdition
tiononexecutionprocedures.Section3.3.1hasexamplesofusingtheabaquscommand.
3. GettingStartedwithABAQUSKeywordEdition Toaccesstheon-lineinformationonthekeywords(moredetailsinsection9.1)
abaqusdoc
4. ABAQUSAnalysisUser’sManual(VolumesI,II,III,IVandV) Tofindoutwhichexamplesmakeuseofaparticularkeyword,illustratedherewiththekeyword
dynamic,
5. Theory
abaqusfindkeywordjob=dynamic
6. ExampleProblemsManual *dynamic
*<CR>
7. ABAQUSBenchmarksProblems
Theoutputwillbewrittentothefilereferredtobyjobandwiththeextensiondatiedynamic.dat.The
8. ABAQUSUserSubroutineReferenceManual
analysesdatafileslistedinthisfilecanbeobtainedusingtheabaqusfetchcommand. Toextracta
9. ABAQUSGlossaryManual copyoftheinputfilesfortheairspringexample
abaqusjob=airspring* fetch
10. ABAQUSKeywordsReferenceManual(VolumesIandII) Torunthepre-processingprogramABAQUS/CAE
abaquscae
11. VerificationManual
ItisalsopossibletosubmitthejobanddothepostprocessingfromABAQUS/CAEwithoutexiting
12. ABAQUSScriptingUser’sManual fromit.
TorunanABAQUSanalysis(bothABAQUS/StandardandExplicit)
13. ABAQUSScriptingReferenceManual abaqusjob=abcd1
TorunthepostprocessingprogramABAQUS/Viewer
14. ABAQUSReleaseNotes
abaqusviewer
15. ABAQUSInstallationandLicensingGuide TocreateanexecutablemodulefromauserwrittenFortranprogramprog1.f(thiswouldcreateprog1.x)
3 4
1.4 Commands 1 INTRODUCTION 1.5 SuggestedCourseofAction 1 INTRODUCTION
abaqusjob=abcd1makeuser=prog1
Toruntheexecutablemodulecreatedusingthemakecommand:
abaqusprog1.x
TorunMSC/PATRAN
patran
ForotherABAQUScommandsseesection3.1.1oftheUser’smanualVol. 1. Section3.3.1has
examplesofitsuse.
1.5 SuggestedCourseofAction
• Newusersarerecommendedtoreadthroughsections1.1.1&1.2.1oftheAnalysisUser’smanual
volumeI.Section1.2.2dealswithconventionsandunits.
TheGettingStartedwithABAQUS/Standardmanualisthebeststartingplacefornewusers.It
Create complex ABAQUS Pre
cae hasexamplesonlinear,non-linear,dynamic,plasticityandcontactproblems.Italsohasagood
Geometry CAE Processing introductiontotheuseofcontinuumelements,shellandbeamelements.
binary
Foruserswhoarelaunchingthemselvesintotheirfirstanalysistherelevantinformationforany
ascii givenanalysisisspreadoverthemanyABAQUSmanuals.
inp
Youneedtoreadalltherelevantsections,makenotesasyougoalongandalsofollowuponall
cross-referencesyoucomeacross.
Message file
Youneedtofindalltheinformationpertainingtothefollowingtopicsforyouranalysis
Printed output msg
– AnalysisType(Procedures)
dat ABAQUS Analysis
– ElementTypes
res
ascii – MaterialBehaviour
Restart binary
file – Loading
odb Output – BoundaryConditions
Database
binary – Output
Post
ABAQUS ps Onlyafterreadingalltherelevantinformationareyouinapositiontorunyourownanalysis.It
Processing isagoodideatofindanexamplewhichisclosesttoyouranalysisrequirement.
Viewer
• Chapter6oftheUsersmanualdealswiththedifferentanalysesandprocedures.Thisisagood
placetostart.
Represents files which are identified by the
extension names. • Chapter17givesanintroductiontothematerialbehaviour. Chapters17to22coverallthe
materialmodelsavailableinABAQUS.
PS - Postscript files ABAQUSprovidesabroadrangeofmaterialmodels.Section17.1.3hasmaterialmodelcombi-
nationtableswhichishelpfulinshowingwhichmaterialpropertiescouldbecombinedtogether
Figure1:ABAQUS/CAE,ABAQUS/ViewerandtheAnalysisModule andwhichcannotbe.
• Chapter23introducestheelementtypes. Lookthroughchapter23to25oftheabovemanual
toidentifytheelementtypestobeusedintheanalysis.Thissectionalsohasinformationonthe
typeofloading.Chapters26to28containsinformationonmorenon-generalspecialistelement
types.
Oncetheelementtypehasbeenidentifiedinthesamesectionalistofactivedof,typeofloading
thatcanbeappliedtotheelementtypeandtheoutputparametersavailablefortheseelements
canbefound.
• LookthroughtheElementIndexinvolumeIIfortheelementtypes.LookthroughtheKeywords
Manualtocheckthevariouskeywords. FollowthereferencestotheAnalysisUser’smanual.
Refertothesectionswhicharerelevanttoyouranalysis.
5 6
2 DATAPREPARATION 2 DATAPREPARATION
• Chapter29(volumeII)hasinformationonloadingandboundaryconditions. Chapter30has
informationonMPC(MultiPointConstraints).Informationoncontactproblemcanbefoundin
chapters31to35.
Solid Create
• Section4.1.1(VolumeI)dealswiththeoutputfromABAQUS. Pro/
ENGINEER Modeler Complex
• SearchthroughthecontentsoftheExampleProblemsManualtofindtheexamplesinthefield Geometry
ofyourinterest.
ascii ascii
• LookthroughthecontentsoftheVerificationandBenchmarksmanualstofindtheexamplesin
cae
thefieldofyourinterest. prt, asm
part assembly
• AnotherusefulsourceisthecoursenotesofthevariouscoursesrunbySIMULIALtd.
• Runanexampleproblemandfamiliariseyourselfwiththevariousfilesandintheuseofthe ABAQUS Pre
variousprogrammodules(ABAQUS,ABAQUS/CAE,ABAQUS/Viewer). PATRAN CAE
Processing
• OutputVariableindexcanbefoundinOI.1nadOI.2forStandardandExplicitrespectively.EI.1
andEI.2hastheElementindexforStandardandExplicitversionsrespectively.
ascii
• Startwithasimplifiedsituationofyouranalysiswithveryfewelements,stepsandincrements. inp Log file
Thentheturnaroundtimewhileyoudebugthedataandrootouttheerrorswillbeshorter.
log ascii
OnceyoufamiliariseyourselfwithABAQUSyoucanrefinethemeshandaddcomplexitytothe
analysis. Printed output Message file
• Inordertofamiliariseoneselfwiththe6.9styleformatoftheinputfilesection2.9.1Definingan dat ABAQUS msg Analysis
AssemblyintheAnalysisUsers’sManualVolume1isrecommendedreading.Thisisessential ascii res Restart
readingonlyifyouneedtomakechangestotheinputfilecreatedbyCAEusingatexteditor. file
binary
Thisisagainifyouareusingfeatures/keywordscurrentlynotsupportedbyCAE.
Output
database odb binary Results
binary fil file
2 DataPreparation
Figure2showsthevariousABAQUSmodulesandtheinter-relationshipbetweenPATRAN,Pro/ENGINEER
programsandABAQUS.AsshowninthisfiguretheABAQUSinputdatafile*.inpcanbecreatedby
PATRANinteractively.ItisalsopossibletousethemeshgenerationcommandsavailableinABAQUS
(section2.4).Ifyouareworkingwithcomplexand/or3-dimensionalgeometriesuseofeitherPATRAN ABAQUS/ Post
orFEMGENisrecommended. PATRAN Viewer Processing
Complex3dimensionalgeometriescanbecreatedinPro/ENGINEERandimportedintoPATRAN
andthenmeshedbeforeaABAQUSanalysis.ItisalsopossibletousethenewABAQUS/CAEmod-
ulewhichprovidesthecapabilityofbothasolidmodeller(Pro/ENGINEER)andapre-processor(PA- ps ps
TRAN).HoweverbecauseCAEisrelativelynewitdoesnotasyetcaterforthefullcapabilitiesoffered
bytheanalysismodules(ABAQUS/Standard&Explicit). + other formats + other formats
ABAQUS/CAEhassolidmodellingcapabilitieswhichmaynotbeascomprehensiveasthatofa
solidmodelersuchasPro/ENGINEERbutneverthelessmaybeadequateformostusersrequirement.
Italsohasanoptionwhereanykeywordswhichisnotyetcateredforusingthemenubasedsystem Modules
canbedirectlytypedinusingatexteditorfromwithinABAQUS/CAE.Theadvantageofdoingthis
withintheABAQUSframeworkinsteadofoutsideisthattheABAQUSdatabasedoesnotgetoutof
stepwiththeinputdata.?? Represents files which are identified by the
AlternativelytheusercanrefertotheABAQUSAnalysisUser’smanualsandtypeintheinput extension names.
datafile(*.inp)inatexteditorconsisitingofABAQUSkeywordanddatalines.. PS − Postscript files
Section2.4givessomesimplecommandsformeshgenerationprovidedwithintheABAQUSpro-
gramitself.
Figure2:ABAQUS,PATRANandPro/ENGINEERPrograms
ThePATRANandFEMGENprogramscanbeusedtogeneratethedatafilesforstructuralandther-
malproblems.Howeverifyourequiretogeneratethedatafileforananalysisinanyotherspecialised
fielditmaynotbepossibletocreatethecompleteinputdatafilereadyforanalysis.Youmayhaveto
7 8
2.1 Units 2 DATAPREPARATION 2.2 ABAQUSInput 2 DATAPREPARATION
createthedatafileforastandardstructuralorthermalproblemandthenwriteoutthe*.inpdatafile. etc),controlparametersfortimeintegrationorthenonlinearsolutionprocedures,theloadingandoutput
Theneditthisfileusingatexteditorandmakethenecessarychangestotheelementtypes,material requests.
propertiesbyreferringtotheABAQUSmanualsandthensubmittinganABAQUSjob. Theprocedureoptiondefinesthetypeofanalysisthatwillbecarriedoutduringastep. Apro-
Section2.2explainswhatconstitutesanABAQUSinputdatafileforasimplestaticanalysisofa cedureoptionisrequiredforeachstep,andmustfollowimmediatelyafterthe*STEPoption. Any
structuralproblem.Theinputdatafileisillustratedforasimpleexample. mixtureofproceduresmaybeusedfromsteptostep;butonlyone procedureisallowedinanysingle
TypepatrantorunthePATRANprogram.Seethe“Beginner’sGuidetoPATRAN”onhowtouse step.
thePATRANprogram. TypefemruntoruntheFEMGVprogram. SeetheFEMGVUserManualon *STATICisoneoftheprocedureoptionsusedfortheexamplehere.Itmeansitisastaticanalysis.
howtousethefemgenprogram.Atrainingguideisalsoavailable. HerefollowsthelistofproceduresavailableinABAQUS.(seesection6.1oftheAnalysisUser’smanual
SeealsotheCUEDwebpagesunderhelp/EngineeringPackages/finiteelements/Preand foraproceduresoverview).
PostProcessingformoreinformationoneitheroftheseprograms.
*BUCKLE
*COUPLED TEMPERATURE-DISPLACEMENT (steady state and transient)
2.1 Units
*COUPLED THERMAL-ELECTRICAL (steady state and transient)
AquestionoftenaskediswhatunitsdoesABAQUSuse?Theanswerisitdoesnotuseanyparticular *DYNAMIC
units. Anotherquestionasked:HowdoesonesettheunitsinABAQUS?Theanswerisyoucannot *FREQUENCY
settheunits.InputparametersaresimplynumbersasfarasABAQUSisconcerned. *GEOSTATIC
ThereisnounitsassociatedwithABAQUS.Theuserhastochooseanappropriatesetofunits. *HEAT TRANSFER (steady-state and transient)
ForstructuralproblemtheusershoulddecideonunitsforLengthandForce. Fortimedependent *MASS DIFFUSION (steady-state and transient)
problemstheunitforTimealsohastobechosen. *MODAL DYNAMIC
Example: *RANDOM RESPONSE
*RESPONSE SPECTRUM
Length(Co-ordinates)-m(metres) *SOILS, CONSOLIDATION
Force -N(Newtons) *SOILS, STEADY STATE
Time -Sec(seconds) *STATIC
*STEADY STATE DYNAMICS
*VISCO
Thenalldependentparametersmustbespecifiedinaconsistentsetofunits.Forexamplestiffness *DYNAMIC, EXPLICIT
shouldbespecifiedinN/m2(Pascals)anddensityinkg/m3.
IfthechosenLengthdimensionismetresthenathicknessof4mmwillbeinputas0.004.Instead TheABAQUS/Explicitmoduleisrunwhentheprocedurespecifiedisdynamic,explicit. Forall
ifthechosenunitswasmmtheninput4.0. otherprocedurestheABAQUS/Standardanalysisisrun.
Itisnotagoodideatoselectanarbitrarysetofunitsatthebeginningandthenhopetosortoutthe AlldatadefinitionsinABAQUSareaccomplishedwithoptionblocks-setofdatadescribingapart
resultslater(Example:Co-ordinates-mm,Young’sModulus-GPa). oftheproblemdefinition. Theuserchoosesthoseoptionsthatarerelevantforaparticularanalysis.
Eachoptionisintroducedbyakeywordline.Keywordlinesbeginwitha*incolumn1,followedby
Quantity SI SI(mm) SI USUnit(ft) USUnit(inch) thekeyword.Example:*MATERIAL.
Length m mm m ft in Iftheoptionrequiresdatalines,theyfollowthekeywordline. Thesyntaxofkeywordanddata
Force N N kN lbf lbf linesisdefinedinsection1.2.1(ABAQUSAnalysisUser’smanualI).Keywordsmayhaveparameters.
Mass kg tonne(103kg) tonne slug lbfs2/in Keywordlinesusetheformatinwhichblanksareignoredandthecommas(,)separatetheparameters.
Time s s s s s Section2.1.1dealswithnodedefinitionand2.2.1dealswithelementdefinition.
Stress Pa(N/m2) MPa(N/mm2) kPa lbf/ft2 psi(lbf/in2) Parametersaresometimesrequired(forexample: onthe*ELEMENToptionwhichintroducesa
Energy J mJ(10−3J) KJ ftlbf inlbf listofelementdefinition,theparameterTYPEisrequiredtotellwhattypeofelement-solid,shell,
Density kg/m3 tonne/mm3 tonne/m3 slug/ft3 lbfs2/in4 beam,etc-isbeingdefined).Manyparametersareoptional.Parametersmayhavevalues.
Example:*MATERIAL,NAME=STEEL
ThisassociatesthenameSTEELwiththematerialdefinition.
2.2 ABAQUSInput
Anylinewhichhas**inthefirsttwocolumnsarecommentlines.Anynumberofcommentlines
Readthroughsection1.1.2(ABAQUSUSER’smanualVolumeI)foranintroductiontotheABAQUS canbeplacedanywhereinthedatafile. Usecommentlineswithexplanationsliberallywherever
inputdatafile.ThisisessentialreadingfornewusersofABAQUS. necessary.Whenyoulookatthesedatafilesafterawhileitwillbeeasiertocomprehendthedata.
TheinputtotheABAQUSprogram(<job-id>.inpor*.inp)containsmodeldataandhistorydata. Warning:Donotuseblanklinesasasubstituteforcommentlinestomaketheinput
Intherestofthemanualthesecondoptionofrepresentingthejob-idwithanasterisk(*)willbe datafilemorereadable.Avoidblanklineswhichcouldleadtoerrors.
adopted.Modeldatadefinesthefiniteelementmodel:theelements,nodes,elementproperties,ma- Whenexperimentingwithsomealternativessomeofthekeywordsanddatalines
terialdefinition-anydatathatspecifiesthemodelitself. Historydatadefineswhathappenstothe canbetakenoutofexecutionbyinserting**inthefirst2columns. Thesecanthenbe
model-thesequenceofeventsorloadingsforwhichthemodel’sresponseissought. re-activatedlaterbyremovingthe**.Thisiseasierthanfirstdeletingandthenhaving
InABAQUStheuserdividesthehistoryintoasequenceofsteps.Eachstepisaperiodofresponse tore-entertheselinesagain.
ofaparticulartype-astaticloading,adynamicresponse,asoilsconsolidationtransientetc. The Warning Figure3showsthesimpleexampleproblembeinganalysed. Figure4showsthe
definitionofastepincludestheproceduretype(staticstressanalysis,transientheattransferanalysis finiteelementmeshusedfortheanalysis.Eachelementisa4-nodedquadrilateral.
9 10
2.2 ABAQUSInput 2 DATAPREPARATION 2.2 ABAQUSInput 2 DATAPREPARATION
Theplateis1metresquare.Theunitsforlengthhasbeenchosentobemetres.The
forceischosentobeinNewtons.TheYoung’smodulusisthenspecifiedinN/m2forconsistency.The
densityisspecifiedinKg/m3. *Preprint, echo=YES, model=YES, history=YES
Bydefaultthisisomittedwhichissameasincludingitwithall3optionssettoNO.Thisisuseful
fordebuggingpurposes.Moreonthislater.
100 N
InABAQUSthefiniteelementmodelisdefinedasanassemblyofpartinstances. Partinstances
arethecomponentsoftheassembly.Wherepartsaredefinedasthemastercomponents.Theinstances
arecopiesofthese.
Thispermitsre-useoftheparts. Ifanassemblyconsistsofsomecomponentswhichareidentical
thenthesecomponentshavetobeonlydefinedonceasasinglepart. Thenthereshouldbeequal
numberofinstancesofthiscomponentrepresentingeachoftheseitem.
1 m Fortheexampleunderconsiderationtheassemblyismadeupofasinglepartwithasingleinstance
ofthatpart.
*Part, name=plate
*End Part
Y Thisrepresentsthepartdefinition.Itsimplyhasthenameplatedefined.Itisemptyotherwise.
1 m Nextcomestheassemblydefinition.
X *Assembly, name=Assembly
**
Figure3:Acantileverexample *Instance, name=plate-1, part=plate
TheassemblyisgiventhenameAssemblyandthisisfollowedbytheinstancedefinition.Herethe
instanceisgivenauniquenameplate-1andthepartoptionidentifiesthepart.Itisagoodpracticeto
nametheinstancederivedfromthepartname.Thisavoidsanyconfusion.HoweverifusingCAEthis
100
willbedoneautomaticallyasisthecasewiththisexample.
7 8 9 Uy
The*NODEoptionbeginsthespecifyingofthenodesanditsco-ordinates.
U
x *NODE
3 4 node ** Node No. X-coord Y-coord
1, 0.0, 0.
5
6 2, 0.5, 0.
4
Firstnumberineachlineisthenodenumberandthisisfollowedbythexandyco-ordinates.Gaps
1 2
areallowedinthenodenumbering.
The*ELEMENToptiondealswiththeelement-nodalconnectivitylist.Theelementtypeisspecified
Y
usingtheTYPEparameter.
1 2 3 Thechoiceofelementtypeisasimportantasanyotheraspectofafiniteelementanalysis. The
quadrilateralelementsthatcanbeusedinaplanestressanalysisareCPS4,CPS4I,CPS4R,CPS8and
X CPS8R.HereCrepresentContinuumandPSrepresentsPlaneStress. Thisisthenfollowedbythe
numberofnodesintheelement.OptionalRwhichfollowsrepresentsReducedintegration.
Figure4:FiniteElementMesh Forillustrativepurposesthelowerorder4-nodedelementsarechosenhere. Becausebendingis
involved(seetheloadingandboundaryconditions)andbecauseoftheuseoflowerorderelementitis
Thefirstoptionisusuallytheheaderfortheanalysis:thisisgivenonthe*HEADINGoption.The bettertousetheincompatiblemodeelement.Ingeneralthehighertheorderoftheelementthemore
nextlinewillbetakenastheheadingandthiswillappearoneachpageoftheprintedoutput(*.dat accuratewillbetheresultsforthesamelevelofdescretisation.
file)whenABAQUShasrun.Itisagoodpracticetoincludealineexplainingtheunitsbeingusedfor CPS4Iisa4-nodedbilinearincompatiblemodesPlaneStresselement.
lengthandforceaspartoftheheading.
*ELEMENT, TYPE=CPS4I
*HEADING ** Element Node-1 Node-2 Node-3 Node-4
SQUARE PLATE SUBJECTED TO POINT LOAD 1, 1, 2, 5, 4
** Job name: cantilever Model name: Model-1 2, 2, 3, 6, 5
** Units : Length - m, Force - N, Stress - N/m2, Time - Sec.
Firstnumberineachlineistheelementnumberandthisisfollowedbythenodenumberslistedin
Thenextparameter*PREPRINTisoptional. theanti-clockwisesequence.Gapsarepermittedintheelementnumbering.
11 12
2.2 ABAQUSInput 2 DATAPREPARATION 2.2 ABAQUSInput 2 DATAPREPARATION
*Elset, elset=_I1, internal, generate HerethematerialisidentifiedbythenameSTEEL.Itisisotropic(TYPE=ISO)whichisthede-
1, 4, 1 faultoption. 2.1E+11istheYoung’smodulusinN/m2and0.3isthePoissonsratio. Thedensityis
7680kg/m3.Allkeywordsthatfollowthe*MATERIALoptionandintroducematerialbehaviour(like
Thiscreatesanelementsetlabelled I1andtheparametergeneratecausestheelements1to4tobe *ELASTIC)definethepropertiesofthismaterial,untilakeywordappearsthatdoesnotdefinematerial
createdwithincrementsinelementnumberbeing1. properties(suchasa*STEPoptionasinthisexample).
Inthefollowinginputtheelementsintheelementset I1arespecifiedtohaveSOLIDSECTION ABAQUSonlyusesthematerialpropertiesthatarerelevantforthecurrentstepandignoresthe
withathicknessof50mms(inthedirectionnormaltothepaper)andtheyarealsoassignedtheSTEEL rest.Thematerialbehaviourdefinitioncanthereforebeascomplexasneeded:
materialpropertieswhichisdefinedbelow:
Planestressandplanestrainanalysisdealwithproblemswherethestructureissubjectedtoin *EXPANSION - thermal expansion
planeloading. Inthecurrentexampleiftheloadingistransverseienormaltotheplaneoftheplate
thenthisceasestobeaplanestressproblem.Itbecomesathreedimensionalproblem.Thenyouneed *PLASTIC
touseshell(example:S4R5,S8R5)elements.
*DENSITY
*Solid Section, elset=_I1, material=steel
** Thiscompletesthemodelpartofthedatainputforthisexample. Restofthedatacomprisesthe
** thickness historypart.
0.05, Theanalysisconsistsof2steps.Inthefirststeploadingisapplied(pre-load)andinthesecondstep
theeigenmodesandfrequenciesarecalculated.
Thenextstatementcompletestheinstancedefinition. Inamoregeneralproblemotherinstance
specificationsfollowsthisuntilalltheinstancespecificationiscomplete. *Step, name=pre-load
pre-loading
*End Instance *Static
**
Thisisthenfollowedbynodesetsandelementsetsthatmayberequiredfortheanalysis. ** Initial Time, Step Time, Min time and Max time.
1., 1., 1e-05, 1.
*Nset, nset=_G4, internal, instance=plate-1, generate ....
1, 7, 3
*Elset, elset=_G4, internal, instance=plate-1 *End Step
1, 3
The*STEPoptionbeginsthestep;the*ENDSTEPoptionendsit.Amorecomplexanalysiswould
*Nset, nset=_G5, internal, instance=plate-1 haveseveralsteps,andmightusethe*RESTARToptiontodivideuptheanalysis.
9,
ThelinewhichfollowstheStepstatementwillbedisplayedintheCAE/Viewerforthisstepand
actsasalabel. ThisisspecifiedwhentheSTEPwascreatedinCAE.Whichshowsthatmeaningful
Thefirstofthesecreatesanodesetcalled G4containingthenodes1,4and7. Thegenerate
headersarepreferablethanthedefaultlabels/headers.
parametermeansthedatalineisinterpretedas
Nexttheboundaryconditionsarelisted.Theideaistofixthelefthandverticalboundaryi.e.the
starting-nodenumber,ending-nodenumber,incrementinnodenumber
nodes1,4and7arefixedinbothXandYdirectionsi.e.PINNED.Thesenodesformthenodeset G4.
Thesecondgroupstheelements1and3intoanelementsetcalled G4.Noticethatthesamename
canbeassignedtonodesetsandelementsets. Thereisnoambiguityherebecausetheentitiesare *Boundary
different. _G4, PINNED
Thelastsetconsistsofthenode9anditformsthenodeset G5.
**
Theassemblyspecificationiscompletedbythefollowingstatement:
ThegeneralformofthedatainputconsistsoftheNodenumberornodesetlabel,Firstd.o.f.con-
*End Assembly strained,Lastd.o.f.constrained,themagnitude.
Thefollowinginputrepresentsthisgeneralform.:
Thematerialdefinitionforthisexampleis
*MATERIAL, NAME=STEEL **B*Nooudnedasreyt, start DOF, fin DOF, value
** _G4, 1, 2, 0.
*DENSITY
7680., **
** HerePINNEDisashortform. Howeverbothareequivalent. Someoftheotherusefulacronyms
*ELASTIC areXSYMM,YSYMMENCASTRE.
** Young’s Mod Poissons ratio Nexttheloadingislisted.HereCLOADstandsforConcentratedloads.Inthelinewhichfollows,
2.1E+11, 0.3
G5isthenodesetwiththenode9towhichtheloadisapplied,2thedirectionordegreeoffreedom
and-100themagnitudeinNewtons.Theminussignindicatesthattheloadisappliedinthenegative
ydirection.
13 14
2.2 ABAQUSInput 2 DATAPREPARATION 2.2 ABAQUSInput 2 DATAPREPARATION
** Name: pt-load Type: Concentrated force AlistofthePRESELECTvariablesforeachtypeofprocedureislistedinthetable4.1.3-1inthe
*Cload USER’smanual(VolumeI).
** Node set, dir Force Magnitude Herepartofthetableforstaticandfrequencyprocedureshavebeenreproducedbelow:
_G5, 2, -100.
** ProcedureType Preselectedelement Preselectednodaland Preselectedenergy
variable(field) surfacevariables variablewritten?
Moreincrementswillbeneededinananalysiswithmaterialnon-linearity(eg. elasto-plasticbe- (field) (history)
haviour)and/orgeometricnon-linearity.ThenaddtheINC=Noption,withNreplacedbyasuitable *STATIC S,E,PE,PEEQ, U,RF,CF, yes
numberofincrements,tothe*STEPstatement. PEMAG CSTRESS,CDISP
Becausetheeigenmodesunderthepre-loadingstateisrequiredthishastobetreatedasanon-linear *FREQUENCY U no
analysiswithlargedeformation.ForthatincludetheNLGEOMparametertothe*STEPline.Thenthe
geometricchangeswillbeaccountedforduringthisandsubsequentsteps.TheINCparameterdefines Thisrepresentstheinformationwrittentheoutputdatabase(*.odbfile).
thenumberofincrementstobe100forthisexample.Incrementsisusedtosub-dividethetotalloading Ascanbeseenthereisnoneedtolistthepre-selectedvariables.Additionaloutputparameterscan
inastep.Thisresultsintheloadbeingappliedinsmallincrements(fractions). beaddedifnecessary.ForexampleCF.Ifyouwanttoplottheforcevsdisplacementatagivennode.
Forthefollowingsetting(timestepof0.01forfirstincrement)thefirst1%ofthetotalloadis
appliedduringthefirstincrementinthestep.Dependingontherateofconvergencetheloadfraction *Restart, write, frequency=1
isincreasedinsubsequentincrementsuntilthetotalloadinghasbeenapplied. **
IntheabsenceoftheNLGEOMparametertheproblemwillbetreatedaslinearelasticandthe ** FIELD OUTPUT: F-Output-1
geometryisnotupdated(iethenodalcoordinatesarenotupdatedbythedisplacementsthattake **
placeduringtheanalysis)andinthesecondsteptheeigenmodeswillbecalculatedbasedonthe *Output, field, variable=PRESELECT
originalgeometryhencetheloadingappliedwillnothaveanyeffectonthemodeorthefrequency. **
** HISTORY OUTPUT: H-Output-1
*STEP, AMPLITUDE=RAMP, NLGEOM, INC=100 **
*STATIC *Output, history, variable=PRESELECT
0.01, 1.0, 1.E-5, 1.0
Bydefaultnoresultsarewrittentotheresultsfile(*.res). Thiskeepsthe*.datfiletobecompact.
Thedataconsistsofinitialtimeincrement(0.01),totaltimestep(1.0),minimum(1.E-5)andmaxi- Thisisfavouringvisualisationoftheresultsintermsofgraphicalplots(contours,deformedshape,
mum(1.0)timeincrementallowed. graphsetc)andlessofprintingofseveraltablesofstresses,strainsanddisplacementswhicharehard
tofathomatthebestoftime.
*RESTART,WRITE Howevertherearetimeswhendebuggingorcarryingspotcheckofcalculationforabenchmark
Thiscreatestherestartfile(*.res)whichisalsousedforre-startingtheanalysis.Thisrecordcanbe problemwhenprintedoutputisneeded.Forthiscasethefollowingstatementsallowsonetoprintout
includedanywherebuthereitisincludedbeforethefirst*STEPrecord. theresultsforcheckingpurposes.
Foralargeanalysiswithmanyelementsandstepstherestartfilecanbeverylarge(severalMBytes). *NODE PRINT, FREQ=1, NSET=_G4
Toreducethesizeoftherestartfileaddthefrequencyoption. U
RF
*RESTART,WRITE,FREQUENCY=N
Thiswritesoutthenodaldisplacements(U)andthereactionforces(RF)tothe*.dat(printedoutput)
WhereNcanbeasuitablenumberappropriatefortheno. ofincrementsusedinthatstep. For
file.ThesettingoftheparameterNSETrestrictstheoutputtothenodesinthatset.
exampleifyouareusing100incrementsinastepthenNcanbesetto10. Theresultswillonlybe
writtentotherestartfileattheendofevery10thincrement. *NODE PRINT, FREQ=1
Alternativelyifyouareonlyinterestedinrestartingtheanalysisattheendofthecurrentanalysis U, RF
thenyoucanusethefollowingcommand:
Toprintthedisplacementsandthereactionsinasingletableusetheabovecommands.
*RESTART,WRITE,OVERLAY
*NODE FILE, FREQ=1
Thiswillwritetheresultsattheendofeveryincrementafterrewindingtherestartfile. Atthe U
endoftheanalysisthe*.resfilewillcontainonlytheresultsofthelastincrement. Iftheanalysisis RF
interruptedforsomereasonthenitwillcontaintheresultsoftheincrementwhichwascompletedjust
Thiswritesoutthenodaldisplacements(U)andthereactionforces(RF)tothe*.filfileforpost
priortotheinterruption.Ifnecessarytheanalysiscanbecontinuedfromtheincrementwrittentothe
processingusingPATRANorFEMGV.LatestversionofPATRAN(2003R2)canalsomakeuseofthe
restartfile.
*.odbfile(ABAQUSoutputdatabase)forpost-processing.
ABAQUSincludesdefaultoutputrequests: theseprovidethenecessaryinformationofelement
variables(stress,strain,etc)andnodalvariables(displacements,reactionforces)whichareusedfor **
post-processingusingtheViewermodule. *EL PRINT, POSITION=INTEGRATION POINT, FREQ=1, ELSET=_G4
Ingeneralusersmayrequestoutputofvariablesatlocations(nodes,elementintegrationpoints) S
thatareofinteresttothem. Thecompletelistofvariablenamescanbefoundinsection4.2.1ofthe E
USER’smanual(VolumeI). COORD
15 16
2.2 ABAQUSInput 2 DATAPREPARATION 2.2 ABAQUSInput 2 DATAPREPARATION
Thiswritesoutthestresses(S),strains(E)andco-ordinates(COORD)atintegrationpointstothe 4, 0., 0.5
*.dat(printedoutput)file. Itisalsopossibletowriteoutthestressesandstrainsaveragedatnode 5, 0.5, 0.5
byspecifyingPOSITION=AVERAGEDATNODES.IfusingthisoptionthenomitCOORDfromthe 6, 1., 0.5
parameterstobewritten. Similarlyinterpolatedvaluesatelementcentroidscanbeprintedusing 7, 0., 1.
POSITION=CENTROIDAL. 8, 0.5, 1.
Hereagaintheoutputisrestrictedtotheelementsintheset G4. 9, 1., 1.
*Element, type=CPS4I
*EL FILE, POSITION=INTEGRATION POINT, FREQ=1 1, 1, 2, 5, 4
S 2, 2, 3, 6, 5
E 3, 4, 5, 8, 7
COORD 4, 5, 6, 9, 8
** Region: (Section-1:Picked)
Thiswritesoutthestresses(S),strains(E)andco-ordinates(COORD)atintegrationpointstothe
*Elset, elset=_I1, internal, generate
*.filfileforusewithuserwrittenpostprocessingprograms.ThenumbersetbytheFREQparameter
1, 4, 1
(1,inthisexample)istheoutputfrequencyintermsofincrements.
** Section: Section-1
UsetheFREQ=0optiontosuppressinformationbeingwrittentothe*.filfileintheaboveexample.
*Solid Section, elset=_I1, material=steel
Thenthedatalinesareomitted.
0.05,
Thefollowingstatementcompletesthefirststep:
*End Instance
*End Step *Nset, nset=_G4, internal, instance=plate-1, generate
1, 7, 3
Sinceweareinterestedintheeigenmodesofthisexamplethenasecondstepasshowncanbe *Elset, elset=_G4, internal, instance=plate-1
included: 1, 3
*Nset, nset=_G5, internal, instance=plate-1
*Step, name=eigenmodes, perturbation 9,
eigenmodes *End Assembly
*Frequency, eigensolver=Lanczos **
5, , , , , ** MATERIALS
..... **
*END STEP *Material, name=steel
*Density
The*FREQUENCYtellstheprogramthatthisstepisafrequencyanalysis(thisshouldnotbecon- 7680.,
fusedwiththeFREQUENCYparameterusedintheoutputoptionswhereitreferstoincrementnum- *Elastic
bers)andthenumber5whichfollowsmeansthattheuserisonlyinterestedinthefirst5eigenmodes. 2.1e+11, 0.3
Thecompleteinputdataislistedbelow: ** ----------------------------------------------------------------
*Heading **
deformation-eigen ** STEP: pre-load
** Job name: cantiever Model name: Model-1 **
Units : Length - m, Force - N, Stress - N/m2, Time - Sec. *Step, name=pre-load, nlgeom
pre-loading
*Preprint, echo=YES, model=YES, history=YES
*Static
**
1., 1., 1e-05, 1.
** PARTS
**
**
*Part, name=plate ** BOUNDARY CONDITIONS
*End Part **
** Name: lhs-fixed Type: Symmetry/Antisymmetry/Encastre
**
** ASSEMBLY *Boundary
_G4, PINNED
**
*Assembly, name=Assembly **
** LOADS
**
*Instance, name=plate-1, part=plate **
*Node ** Name: pt-load Type: Concentrated force
1, 0., 0. *Cload
_G5, 2, -100.
2, 0.5, 0.
3, 1., 0. **
17 18
2.2 ABAQUSInput 2 DATAPREPARATION 2.3 Exercises 2 DATAPREPARATION
** OUTPUT REQUESTS *EL PRINT, POSITION=INTEGRATION POINT, FREQ=1
** S
*Restart, write, frequency=1 E
** *EL FILE, POSITION=INTEGRATION POINT, FREQ=1
** FIELD OUTPUT: F-Output-1 S
** E
*Output, field, variable=PRESELECT *End Step
**
** HISTORY OUTPUT: H-Output-1
**
*Output, history, variable=PRESELECT Data File : cantilever.inp
**
*NODE PRINT, FREQ=1 Figure5showstheorganisationofamodeldefinedintermsofanassemblyofpartinstance.This
U organisationofthemodelmatchesthewaymodelsarecreatedinABAQUS/CAE.
RF Seethesection2.9.1oftheABAQUSUser’smanual(Volume1)foracompletedefinitionofan
*NODE FILE, FREQ=1 assembly.
U
RF 2.3 Exercises
**
*EL PRINT, POSITION=INTEGRATION POINT, FREQ=1 2.3.1 Exercise1
S
Whatarethechangesyouneedtomaketotheaboveinputfileiftheloadingistransverseienormalto
E
theplateinthezdirection?
COORD
*EL FILE, POSITION=INTEGRATION POINT, FREQ=1
S 2.3.2 Exercise2
E
Reruntheaboveexampleasanon-linearanalysiswithahigherloadandseetheeffectithasonthe
COORD
frequenciesinthesecondstep.
*End Step Makethefollowingchanges.
** ----------------------------------------------------------------
** *STEP, AMPLITUDE=RAMP, NLGEOM, INC=100
** STEP: eigenmodes *STATIC
** 0.01, 1.0, 1.E-5, 1.0
*Step, name=eigenmodes, perturbation
eigenmodes **
*Frequency, eigensolver=Lanczos *CLOAD, OP=NEW
5, , , , , _G5, 2, -200.E6
**
** OUTPUT REQUESTS *NODE PRINT, FREQ=10
** U
*Restart, write, frequency=1 RF
** *NODE FILE, FREQ=10
** FIELD OUTPUT: F-Output-2 U
** RF
*Output, field **
*Node Output *EL PRINT, POSITION=INTEGRATION POINT, FREQ=10
U, S
*Element Output E
S,
*STEP, NLGEOM
**
Frequency analysis
*NODE PRINT, FREQ=1
U **
*NODE FILE, FREQ=1 *FREQUENCY
U
**
19 20