Getting Started with Abaqus: Interactive Edition - iMechanica

24 Pages·2009·0.85 MB·English

Appendix B: Abaqus/CAE: A BASIC TUTORIAL
Appendix B: Creating and Analyzing a Simple Model in
Abaqus/CAE
ThefollowingsectionisabasictutorialfortheexperiencedAbaqususer. ItleadsyouthroughtheAbaqus/CAE
modeling process by visiting each of the modules and showing you the basic steps to create and analyze a
simplemodel. Toillustrateeachofthesteps,youwillfirstcreateamodelofasteelcantileverbeamandload
itstopsurface(seeFigureB–1).
0.5 MPa
20 mm
25 mm
200 mm
Figure B–1 A loaded cantilever beam.
You will then analyze the beam and plot the resulting stresses and displacements. The entire tutorial takes
approximately90minutestocomplete.
Thefollowingtopicsarecovered:
• “UnderstandingAbaqus/CAEmodules,”SectionB.1
• “UnderstandingtheModelTree,”SectionB.2
• “Creating apart,”Section B.3
• “Creatingamaterial,”SectionB.4
• “Definingandassigningsectionproperties,”SectionB.5
• “Assemblingthemodel,”SectionB.6
• “Definingyouranalysissteps,”SectionB.7
• “Applyingaboundaryconditionandaloadtothemodel,”SectionB.8
• “Meshingthemodel,”SectionB.9
• “Creatingandsubmittingananalysisjob,”SectionB.10
• “Viewingtheresultsofyouranalysis,”SectionB.11
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B.1 Understanding Abaqus/CAE modules
Abaqus/CAE is divided into modules, where each module defines an aspect of the modeling process;
forexample,definingthegeometry,definingmaterialproperties,andgeneratingamesh. Asyoumove
frommoduletomodule,youbuildthemodelfromwhichAbaqus/CAEgeneratesaninputfilethatyou
submittoAbaqus/StandardorAbaqus/Explicitforanalysis. Forexample,youusethePropertymodule
to define material and section properties and the Step module to choose an analysis procedure. The
Abaqus/CAEpostprocessoriscalledtheVisualizationmoduleandisalsolicensedasaseparateproduct
called Abaqus/Viewer.
YouenteramodulebyselectingitfromtheModulelistinthecontextbar,asshowninFigureB–2.
Figure B–2 Selecting a module.
For the cantilever beam tutorial, you will enter the following Abaqus/CAE modules and perform the
following tasks:
Part
Sketchatwo-dimensionalprofileandcreateapartrepresentingthecantileverbeam.
Property
Definethematerialpropertiesandothersectionpropertiesofthebeam.
Assembly
Assemblethemodelandcreatesets.
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Step
Configuretheanalysisprocedureandoutputrequests.
Load
Applyloadsandboundaryconditionstothebeam.
Mesh
Mesh the beam.
Job
Createajobandsubmititforanalysis.
Visualization
Viewtheresultsoftheanalysis.
AlthoughtheModulelistinthecontextbarliststhemodulesinalogicalsequence,youcanmoveback
andforthbetweenmodulesatwill. However,certainobviousrestrictionsapply;forexample,youcannot
assignsectionpropertiestogeometrythathasnotyetbeencreated.
AcompletedmodelcontainseverythingthatAbaqus/CAEneedstogenerateaninputfileandstart
theanalysis. Abaqus/CAEusesamodeldatabasetostoreyourmodels. WhenyoustartAbaqus/CAE,
theStartSessiondialogboxallowsyoutocreateanew,emptymodeldatabaseinmemory. Afteryou
startAbaqus/CAE,youcansaveyourmodeldatabasetoadiskbyselectingFile→Savefromthemain
menubar;toretrieveitfromadisk,selectFile→Open.
For a complete listing of which module generates a particular keyword, see “Abaqus keyword
browser table,” Section A.1 of the Abaqus/CAE User’s Manual, in the online HTML version of this
manual.
B.2 Understanding the Model Tree
TheModelTreeprovidesavisualdescriptionofthehierarchyofitemsinamodel. FigureB–3showsa
typical Model Tree.
Items in the Model Tree are represented by small icons; for example, the Steps
icon, . Inaddition,parenthesesnexttoanitemindicatethattheitemisacontainer,
andthenumberintheparenthesesindicatesthenumberofitemsinthecontainer. Youcanclickonthe
“ ”and“−”signsintheModelTreetoexpandandcollapseacontainer. Therightandleftarrowkeys
perform thesameoperation.
ThearrangementofthecontainersanditemsintheModelTreereflectstheorderinwhichyouare
expected to create your model. As noted earlier, a similar logic governs the order of modules in the
modulemenu—youcreatepartsbeforeyoucreatetheassembly,andyoucreatestepsbeforeyoucreate
loads. Thisarrangementisfixed—youcannotmoveitemsintheModelTree.
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Figure B–3 Model Tree.
TheModelTreeprovidesmostofthefunctionalityofthemainmenubarandthemodulemanagers.
For example, if you double-click on the Parts container, you can create a new part (the equivalent of
selectingPart→Createfromthemainmenubar).
The instructions for the examples that follow will focus on using the Model Tree to access the
functionality of Abaqus/CAE. Menu bar actions will be considered only when necessary (e.g., when
creatingafiniteelementmeshorpostprocessingresults).
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B.3 Creating a part
YoucancreatepartsthatarenativetoAbaqus/CAE,oryoucanimportpartscreatedbyotherapplications
eitherasageometricrepresentationorasafiniteelementmesh.
You will start the cantilever beam tutorial by creating a three-dimensional, deformable solid
body. Youdothisbysketchingthetwo-dimensionalprofileofthebeam(arectangle)andextrudingit.
Abaqus/CAEautomaticallyenterstheSketcherwhenyoucreateapart.
Abaqus/CAEoftendisplaysashortmessageinthepromptareaindicatingwhatitexpectsyoutodo
next, asshown inFigureB–4.
previous prompt
cancel
Figure B–4 Messages and instructions are displayed in the prompt area.
ClicktheCancelbuttontocancelthecurrenttask. ClickthePreviousbuttontocancelthecurrentstep
inthetaskandreturntothepreviousstep.
To create the cantilever beam:
1. If you did not already start Abaqus/CAE, type abaqus cae. Resize your windows so that you
canfollowthetutorialandseetheAbaqus/CAEmainwindow.
2. From the Start Session dialog box that appears, select Create Model Database. If you are
alreadyinanAbaqus/CAEsession,selectFile→Newfromthemainmenubar.
Abaqus/CAEentersthePartmodule. TheModelTreeappearsintheleftsideofthemainwindow.
Between the Model Tree and the canvas is the Part module toolbox. A toolbox contains a set of
icons that allow expert users to bypass the menus in the main menu bar. For many tools, as you
selectanitemfromthemainmenubarortheModelTree,thecorrespondingtoolishighlightedin
themoduletoolboxsoyoucanlearnitslocation.
3. IntheModelTree,double-clickthePartscontainertocreateanewpart.
TheCreate Partdialogboxappears. Abaqus/CAEalsodisplaystextinthepromptareanearthe
bottomofthewindowtoguideyouthroughtheprocedure.
YouusetheCreatePartdialogboxtonamethepart;tochooseitsmodelingspace,type,andbase
feature;andtosettheapproximatesize. Youcaneditandrenameapartafteryoucreateit;youcan
alsochangeitsmodelingspaceandtypebutnotitsbasefeature.
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4. Name the part Beam. Accept the default settings of a three-dimensional, deformable body and a
solid,extrudedbasefeature. IntheApproximatesizetextfield,type300.
5. ClickContinuetoexittheCreatePartdialogbox.
Abaqus/CAE automatically enters the Sketcher. The Sketcher toolbox appears in the left side of
the main window, and the Sketcher grid appears in the viewport. The Sketcher contains a set of
basictoolsthatallowyoutosketchthetwo-dimensionalprofileofyourpart. Abaqus/CAEenters
theSketcherwheneveryoucreateoreditapart. TofinishusingaSketchertool,clickmousebutton
2intheviewportorselectanewtool.
Tip: LikealltoolsinAbaqus/CAE, ifyousimplypositionthecursoroveratoolinthe
Sketchertoolboxforashorttime,asmallwindowappearsthatgivesabriefdescription
of the tool.
ThefollowingaspectsoftheSketcherhelpyousketchthedesiredgeometry:
• TheSketchergridhelpsyoupositionthecursorandalignobjectsintheviewport.
• DashedlinesindicatetheX-andY-axesofthesketchandintersectattheoriginofthesketch.
• Atriad inthelower-leftcorneroftheviewportindicatestherelationshipbetweenthesketch
planeandtheorientationofthepart.
• Whenyouselectasketchingtool,Abaqus/CAEdisplaystheX-andY-coordinatesofthecursor
intheupper-leftcorneroftheviewport.
6. Tosketchtheprofileofthecantileverbeam,youneedtoselecttherectangledrawingtool .
The rectangle drawing tool appears in the Sketcher toolbox with a white background indicating
that you selected it. Abaqus/CAE displays prompts in the prompt area to guide you through the
procedure.
7. Intheviewport,sketchtherectangleusingthefollowingsteps:
a. You will first sketch a rough approximation of the beam and then use constraints and
dimensionstorefinethesketch. Selectanytwopointsastheoppositecornersoftherectangle.
b. Clickmousebutton2anywhereintheviewporttoexittherectangletool.
Note: If you are a Windows user with a 2-button mouse, press both mouse buttons
simultaneouslywheneveryouareaskedtopressmousebutton2.
c. TheSketcherautomaticallyaddsconstraintstothesketch(inthiscasethefourcornersofthe
rectangleareassignedperpendicularconstraintsandoneedgeisdesignatedashorizontal).
d. Use the dimension tool to dimension the top and left edges of the rectangle. The top
edgeshouldhaveahorizontaldimensionof200mm,andtheleftedgeshouldhaveavertical
dimension of 20 mm. When dimensioning each edge, simply select the line, click mouse
button1topositionthedimensiontext,andthenenterthenewdimensioninthepromptarea.
e. ThefinalsketchisshowninFigureB–5.
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200.
20.
H
Figure B–5 Sketch of the rectangle.
8. IfyoumakeamistakewhileusingtheSketcher,youcandeletelinesinyoursketch,asexplainedin
thefollowing procedure:
a. FromtheSketchertoolbox,clicktheDeletetool, .
b. Fromthesketch,clickalinetoselectit.
Abaqus/CAEhighlightstheselectedlineinred.
c. Clickmousebutton2intheviewporttodeletetheselectedline.
d. Repeatstepsbandcasoftenasnecessary.
e. Clickmousebutton2intheviewporttofinishusingtheDeletetool.
9. Fromthepromptarea(nearthebottomofthemainwindow),clickDonetoexittheSketcher.
Note: Ifyoudon’tseetheDonebuttoninthepromptarea,continuetoclickmousebutton2inthe
viewport until it appears.
10. Becauseyouarecreatinganextrudedpart,Abaqus/CAEdisplaystheEditBaseExtrusiondialog
boxforyoutoselectthedepth. Optionalparameterstomodifytheextrusionshapearealsoavailable.
IntheDepthfield,erasethedefaultvalueof30andtypeavalueof25.0. ClickOKtoacceptthis
value.
Abaqus/CAEdisplaysanisometricviewofthenewpart,asshowninFigureB–6.
Tohelpyouorientthecantileverbeamduringthemodelingprocess,Abaqus/CAEdisplaysatriad
inthelower-leftcornerindicatingtheorientationoftheX-,Y-,andZ-axes.
11. Beforeyoucontinuethetutorial,saveyourmodelinamodeldatabasefile.
a. From the main menu bar, select File→Save. The Save Model Database As dialog box
appears.
b. Type a name for the new model database in the File Name field, and click OK. You do not
needtoincludethefileextension;Abaqus/CAEautomaticallyappends.caetothefilename.
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2
3 1
Figure B–6 Isometric view of the beam.
Abaqus/CAE stores the model database in a new file and returns to the Part module. The
titlebaroftheAbaqus/CAEwindowdisplaysthepathandnameofthemodeldatabase. You
shouldalwayssaveyourmodeldatabaseatregularintervals(forexample,eachtimeyouswitch
modules).
B.4 Creating a material
ForthecantileverbeamtutorialyouwillcreateasinglelinearelasticmaterialwithYoung’smodulusof
209×103 MPaandPoisson’sratioof0.3.
To define a material:
1. IntheModelTree,double-clicktheMaterialscontainertocreateanewmaterial.
Abaqus/CAEswitchestothePropertymodule,andtheEditMaterialdialogboxappears.
2. NamethematerialSteel. Usethemenubarunderthebrowserareaofthematerialeditortoreveal
menuscontainingalltheavailablematerialoptions. Someofthemenuitemscontainsubmenus;for
example,FigureB–7showstheoptionsavailableundertheMechanical→Elasticitymenuitem.
Whenyouselectamaterialoption,theappropriatedataentryformappearsbelowthemenu.
3. Fromthematerialeditor’smenubar,selectMechanical→Elasticity→Elastic.
Abaqus/CAEdisplaystheElasticdataform.
4. Type a value of 209.E3 for Young’s modulus and a value of 0.3 for Poisson’s ratio in the
respectivefields,asshowninFigureB–8. Use[Tab]tomovebetweencells.
5. ClickOKtoexitthematerialeditor.
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Figure B–7 SubmenusavailableundertheMechanicalmenu.
FigureB–8 Enteringdatavaluesfortheelasticmaterialproperties.
B.5 Defining and assigning section properties
Youdefinethepropertiesofapartthroughsections. Afteryoucreatethesection,youcanuseoneofthe
followingtwomethodstoassignthesectiontothepartinthecurrentviewport:
• Youcansimplyselecttheregionfromthepartandassignthesectiontotheselectedregion.
• YoucanusetheSettoolsettocreateahomogeneoussetcontainingtheregionandassignthesection
to the set.
Forthecantileverbeamtutorialyouwillcreateasinglehomogeneoussolidsectionthatyouwillassign
tothebeambyselectingthebeamfromtheviewport. Thesolidsectionwillcontainareferencetothe
materialSteelthatyoujustcreated.
Defining a homogeneous solid section
Ahomogeneoussolidsectionisthesimplestsectiontypethatyoucandefine;itincludesonlyamaterial
referenceandaplanestress/planestrainthickness.
To definethe homogeneous solid section:
1. IntheModelTree,double-clicktheSectionscontainertocreateasection.
TheCreate Sectiondialogboxappears.
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2. IntheCreate Sectiondialogbox:
a. NamethesectionBeamSection.
b. IntheCategorylist,acceptSolidasthedefaultcategoryselection.
c. IntheTypelist,acceptHomogeneousasthedefaulttypeselection.
d. Click Continue.
TheEdit Sectiondialogboxappears.
3. In the dialog box:
a. AcceptthedefaultselectionofSteelfortheMaterialassociatedwiththesection.
b. Acceptthedefaultvalueof1forthePlanestress/strainthickness.
c. Click OK.
Assigning the section to the cantilever beam
ThesectionBeamSectionmustbeassignedtothepart.
To assign thesectionto thecantileverbeam:
1. In the Model Tree, expand the branch for the part named Beam by clicking the “ ” symbol to
expandthePartscontainerandthenclickingthe“ ”symboltoexpandtheBeamitem.
2. Double-clickSectionAssignmentsinthelistofpartattributesthatappears.
Abaqus/CAEdisplayspromptsinthepromptareatoguideyouthroughtheprocedure.
3. Clickanywhereonthebeamtoselecttheregiontowhichthesectionwillbeapplied.
Abaqus/CAEhighlightstheentirebeam.
4. Click mouse button 2 in the viewport or click Done in the prompt area to accept the selected
geometry.
TheEditSectionAssignmentdialogboxappearscontainingalistofexistingsections.
5. AcceptthedefaultselectionofBeamSectionasthesection,andclickOK.
Abaqus/CAEassignsthesolidsectiontothebeam,colorstheentirebeamaquatoindicatethatthe
regionhasasectionassignment,andclosestheEditSectionAssignmentdialogbox.
Notethefollowingkeypoint:
• Whenyouassignasectiontoaregionofapart,theregiontakesonthematerialpropertiesassociated
with the section.
B.6 Assembling the model
Eachpartthatyoucreateisorientedinitsowncoordinatesystemandisindependentoftheotherparts
inthemodel. Althoughamodelmaycontainmanyparts,itcontainsonlyoneassembly. Youdefinethe
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