7/28/2019 Buckling Tutorial

1/202011 Hormoz Zareh & Donald Bell 1 Portland State University, Mechanical Engineering

Abaqus/CAE (ver.6.10)NonlinearBucklingTutorialProblemDescriptionThis is the NAFEMS1 proposed benchmark (Lees frame buckling) problem. The applied load is based on

the normalized (EI/L

2

) value of F = 996.389N. The analysis will investigate post-buckling nonlinearbehavior of the frame at the applied load location.

This tutorial will also describe x-y plotting capability in Abaqus/CAE, including combining variables to

generate load-displacement plots.

E = 71.74109N/m

2

= 0.0

L = 1.2 m

1 National Agency for Finite Element Methods and Standards, NAFEMS Non-Linear Benchmarks (Glasgow:

NAFEMS, Oct., 1989., Rev. 1.) Test No. NL7.

0.2 L 0.8 L

L

0.03

0.02

F

7/28/2019 Buckling Tutorial

2/202011 Hormoz Zareh & Donald Bell 2 Portland State University, Mechanical Engineering

AnalysisSteps

1. StartAbaqusandchoosetocreateanewmodeldatabase2. InthemodeltreedoubleclickonthePartsnode(orrightclickonpartsandselectCreate)

3. IntheCreatePartdialogbox(shownabove)namethepartanda. Select2DPlanarb. SelectDeformablec. SelectWired. Setapproximatesize=10e. ClickContinue

4. Createthegeometryshownbelow(notdiscussedhere)

7/28/2019 Buckling Tutorial

3/202011 Hormoz Zareh & Donald Bell 3 Portland State University, Mechanical Engineering

5. DoubleclickontheMaterialsnodeinthemodeltree

a. Namethenewmaterialandgiveitadescriptionb. ClickontheMechanicaltabElasticityElastic

i.Enter

a

Youngs

modulus

of

71740000000,

and

Poissons

ratio

of

0

c. ClickOK

7/28/2019 Buckling Tutorial

4/202011 Hormoz Zareh & Donald Bell 4 Portland State University, Mechanical Engineering

6. DoubleclickontheProfilesnodeinthemodeltreea. NametheprofileandselectRectangularb. ClickContinuec. Enter0.03foraand0.02forbd. ClickOK

7. DoubleclickontheSectionsnodeinthemodeltreea. NamethesectionbeamandselectBeamforthecategoryandBeamforthetypeb. ClickContinuec. Selecttheprofilecreatedabove(rect_beam) andthematerialcreatedabove(Material1)

7/28/2019 Buckling Tutorial

5/202011 Hormoz Zareh & Donald Bell 5 Portland State University, Mechanical Engineering

d.ClickOK

8. ExpandthePartsnodeinthemodeltree,expandthenodeofthepartjustcreated,anddoubleclickonSectionAssignments

a. SelecttheentiregeometryintheviewportandpressDoneinthepromptareab. Selectthesectioncreatedabove(beam)c. ClickOK

9. InthetoolboxareaclickontheAssignBeamOrientationbuttona. Selectallthegeometryb. ClickDone

7/28/2019 Buckling Tutorial

6/202011 Hormoz Zareh & Donald Bell 6 Portland State University, Mechanical Engineering

c. Leavethedefaultvaluesof0.0,0.0,1.0d. PresstheEnterkeye. Thebeamnormalsshouldbeorientedasshownbelow.f. ClickOKtoconfirm

10.ExpandtheAssemblynodeinthemodeltreeandthendoubleclickonInstancesa. SelectDependentfortheinstancetypeb. ClickOK

7/28/2019 Buckling Tutorial

7/202011 Hormoz Zareh & Donald Bell 7 Portland State University, Mechanical Engineering

11.DoubleclickontheStepsnodeinthemodeltreea. Namethestep,settheproceduretoGeneral,andselectStatic,Riks,ClickContinueb. OntheBasictab

i. Givethestepadescriptionandii. Setgeometricnonlinearitieson(Nlgeom=ON)iii. UnderStoppingcriteriacheckMaximumloadproportionalityfactorandsetto30

c. OntheIncrementation tab,i. Settheinitialarclengthincrementsizeto0.1ii. Setthemaximumarclengthincrementsizeto2iii. Setthemaximumnumberofincrementsto200

7/28/2019 Buckling Tutorial

8/202011 Hormoz Zareh & Donald Bell 8 Portland State University, Mechanical Engineering

d. ClickOK12.DoubleclickontheBCsnodeinthemodeltree

a. NametheboundaryconditionedPinnedandselectDisplacement/Rotationforthetypeb. ClickContinue

c. SelectthetwofreeendsoftheframeandclickDonei. Note:toselectmultipleitems,holdtheshiftkey

d. SelectU1andU2andsettozero,clickOK

7/28/2019 Buckling Tutorial

9/202011 Hormoz Zareh & Donald Bell 9 Portland State University, Mechanical Engineering

13.DoubleclickontheLoadsnodeinthemodeltree

a. NametheloadandselectConcentratedforceasthetypeb. ClickContinue

c. Selectthepointalongthetopbeamnearthecorner,ClickDoned. SetCF1to0andCF2to 996.389e. ClickOK

7/28/2019 Buckling Tutorial

10/202011 Hormoz Zareh & Donald Bell 10 Portland State University, Mechanical Engineering

14.InthemodeltreedoubleclickonMeshfortheframepart,andinthetoolboxareaclickontheAssignElementTypeicon

a. Selecttheentiregeometryb. SelectStandardforelementtypec. SelectLinearforgeometricorderd. SelectBeamforfamilye. Notethatthenameoftheelement(B21)anditsdescriptionaregivenbelowtheelementcontrolsf. ClickOK

7/28/2019 Buckling Tutorial

11/202011 Hormoz Zareh & Donald Bell 11 Portland State University, Mechanical Engineering

15.In

the

toolbox

area

click

on

the

Seed

Part

icon

a. Enter0.08forApproximateglobalsize,clickOK

7/28/2019 Buckling Tutorial

12/202011 Hormoz Zareh & Donald Bell 12 Portland State University, Mechanical Engineering

16.InthetoolboxareaclickontheMeshParticon,ClickYes

17.Createasetfortheuppercentervertexa. ExpandtheAssemblynodeinthemodeltree,andthendoubleclickonsetsb. Namethesetandselectgeometryforthetype,ClickContinuec. Selectthevertexwheretheloadisapplied,ClickDone

18.ExpandtheHistoryOutputRequestsnodeinthemodeltree,andthenrightclickonHOutput1(HOutput1wasautomaticallygeneratedwhencreatingthestep)andselectDelete

19.DoubleclickontheHistoryOutputRequestsnodea. NamethehistoryandselectContinueb. SetthedomaintoSetsandselectthesetcreatedabove

7/28/2019 Buckling Tutorial

13/202011 Hormoz Zareh & Donald Bell 13 Portland State University, Mechanical Engineering

c. Leavethefrequencysettoeveryincrement(n=1)d. FortheoutputvariablesselecttheU2displacement

20.InthemodeltreedoubleclickontheJobnodea. Namethejobframe_buckleb. Givethejobadescription

7/28/2019 Buckling Tutorial

14/202011 Hormoz Zareh & Donald Bell 14 Portland State University, Mechanical Engineering

21.InthemodeltreerightclickonthejobjustcreatedandselectSubmita. WhileAbaqusissolvingtheproblemrightclickonthejobsubmitted,andselectMonitor

b. IntheMonitorwindowcheckthattherearenoerrorsorwarningsi. Ifthereareerrors,investigatethecause(s)beforeresolvingii. Iftherearewarnings,determineifthewarningsarerelevant,somewarningscanbesafely

ignored

iii. Inthefarrightcolumn,notehowAbaqusadjustedtheincrement

22.Inthemodeltreerightclickonthesubmittedandsuccessfullycompletedjob,andselectResults

7/28/2019 Buckling Tutorial

15/202011 Hormoz Zareh & Donald Bell 15 Portland State University, Mechanical Engineering

23.InthemenubarclickonViewportViewportAnnotationsOptionsa. UnchecktheShowcompassoptionb. ThelocationsofviewportitemscanbespecifiedonthecorrespondingtabintheViewport

AnnotationsOptions

24.Displaythedeformedcontourofthe(Von)Misesstressa. Inthetoolboxareaclickonthefollowingicons

i. PlotContoursonDeformedShapeb. Notethatwhenincludingtheeffectsofgeometricnonlinearities,thedeformationscalefactor

defaultstoavalueof1

7/28/2019 Buckling Tutorial

16/202011 Hormoz Zareh & Donald Bell 16 Portland State University, Mechanical Engineering

25.Clickonthearrowsonthecontextbartochangethetimestepbeingdisplayeda. Clickonthethreesquarestobringuptheframeselectorsliderbar

26.Ontheresultstree,expandtheHistoryOutputnodeanddoubleclickonthedisplacementhistorycreated

a. NoticethatdisplacementitplottedagainstArcLength,notLoadorLoadProportionalityFactor.b. Toplotloadagainstdisplacement,wewillneedtoextractthevaluesforLoadanddisplacementfrom

theFieldOutputs.

7/28/2019 Buckling Tutorial

17/202011 Hormoz Zareh & Donald Bell 17 Portland State University, Mechanical Engineering

27.IntheToolboxareaclickontheCreateXYDataicon

a. ChooseODBfieldoutputforSourceandclickContinueb. OntheVariablestab

i. SelectUniqueNodalforPositionii. ExpandCF:PointloadsandselectCF2iii.

Expand

U:

Spatial

displacement

and

select

U2

c. SelecttheElements/Nodestabi. SelectNodeSetsforMethodii. SelectthesetcreatedearlierTop

7/28/2019 Buckling Tutorial

18/202011 Hormoz Zareh & Donald Bell 18 Portland State University, Mechanical Engineering

d. ClickSave,thenOKonthenextwindowe. ClickDismissontheXYDatafromODBFieldOutputwindow

28.ExpandtheXYDatanodeontheresultstree.a. Thereshouldnowbetwosetsofdataunderthenodeasshown.

b. DoubleclicktheXYDatanodec. ForSourceselectOperateonXYdatad. FromtheOperatorslistselectcombine(X,X),Itshouldappearintheexpressionboxatthetopof

thewindow.

i. Thecombine(X,X)operatorcombinestwosetsofsavedXYdataii. TheYvaluesofthefirstargumentbecometheXvaluesofthenewXYdataiii. TheYvaluesofthesecondargumentbecometheYvaluesofthenewXYdataiv. ThevaluesarecombinedwherevertheXvaluesofthetwoargumentsalignv. FormoredetailseeAbaqus/CAEUsersManualsection45.4.39,CombiningtwoXYdata

objects

7/28/2019 Buckling Tutorial

19/202011 Hormoz Zareh & Donald Bell 19 Portland State University, Mechanical Engineering

e. SelectU:U2P1:PART.FromtheXYDatasectionandclickAddtoExpressionf. SelectCF:CF2PI:PART.FromtheXYDatasectionandclickAddtoExpressiong. Sincethe loadanddisplacementbothincreaseinthenegativedirection,theyneedtobemultiplied

by 1tomakeloadanddisplacementincreaseinthepositivedirection.

h. Thefinalexpressionshouldlooklike:

i. ClickSaveAs,nameitloaddisplacement,clickOKj. ClosetheOperateonXYDatawindow

29.RightclickonloaddisplacementundertheXYDatanodeandselectPlot

a. Thebucklingbehaviorcanbeseenintheplot.

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30.ThisdatacanalsobecopiedintoExcelorotherprograms.a. RightclickonloaddisplacementundertheXYDatanodeandselectEditb. Selectallthedataintheeditwindow,rightclickandchooseCopyc. OpenExcel,rightclickinanemptycellandchoosePaste