铰节点.docx
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铰节点.docx
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铰节点
ThistutorialwascreatedusingANSYS5.7.1.Thistutorialwillintroduce:
∙theuseofmultipleelementsinANSYS
∙elementsCOMBIN7(Joints)andCOMBIN14(Springs)
∙obtaining/storingscalarinformationandstorethemasparameters.
A1000Nverticalloadwillbeappliedtoacatapultasshowninthefigurebelow.Thecatapultisbuiltfromsteeltubingwithanouterdiameterof40mm,awallthicknessof10,andamodulusofelasticityof200GPa.Thespringshaveastiffnessof5N/mm.
1.Openpreprocessormenu
/PREP7
2.GiveexampleaTitle
UtilityMenu>File>ChangeTitle...
/title,Catapult
3.DefineElementTypes
Forthisproblem,3typesofelementsareused:
PIPE16,COMBIN7(RevoluteJoint),COMBIN14(Spring-Damper).Itisthereforerequiredthatthetypesofelementsaredefinedpriortocreatingtheelements.Thiselementhas6degreesoffreedom(translationalongtheX,YandZaxis,androtationabouttheX,YandZaxis).
a.DefinePIPE16
With6degreesoffreedom,thePIPE16elementcanbeusedtocreatethe3Dstructure.
▪Preprocessor>ElementType>Add/Edit/Delete...>click'Add'
▪Select'Pipe','Elaststraight16'
▪Clickon'Apply'Youshouldsee'Type1PIPE16'inthe'ElementTypes'window.
b.DefineCOMBIN7
COMBIN7(RevoluteJoint)willallowthecatapulttorotateaboutnodes1and2.
▪Select'Combination','RevoluteJoint7'
▪Click'Apply'.
c.DefineCOMBIN14
Nowwewilldefinethespringelements.
▪Select'Combination','Springdamper14'
▪Clickon'OK'
Inthe'ElementTypes'window,thereshouldnowbethreetypesofelementsdefined.
4.DefineRealConstants
RealConstantsmustbedefinedforeachofthe3elementtypes.
a.PIPE16
▪Preprocessor>RealConstants>Add/Edit/Delete...>click'Add'
▪SelectType1PIPE16andclick'OK'
▪Enterthefollowingproperties,thenclick'OK'
OD=40
TKWALL=10
b.'Set1'willnowappearinthedialogbox
c.COMBIN7(Joint)
Fiveofthedegreesoffreedom(UX,UY,UZ,ROTX,andROTY)canbeconstrainedwithdifferentlevelsofflexibility.Thesecanbedefinedbythe3realconstants:
K1(UX,UY),K2(UZ)andK3(ROTX,ROTY).Forthisexample,wewillusehighvaluesforK1throughK3sinceweonlyexpectthemodeltorotateabouttheZaxis.
▪Click'Add'
▪Select'Type2COMBIN7'.Click'OK'.
▪Inthe'RealConstantsforCOMBIN7'window,enterthefollowinggeometricproperties(thenclick'OK'):
X-YtransnationalstiffnessK1:
1e9
ZdirectionalstiffnessK2:
1e9
RotationalstiffnessK3:
1e9
▪'Set2'willnowappearinthedialogbox.
Note:
Theconstantsthatwedefineinthisproblemrefertotherelationshipbetweenthecoincidentnodes.ByhavinghighvaluesforthestiffnessintheX-YplaneandalongtheZaxis,weareessentiallyconstrainingthetwocoincidentnodestoeachother.
d.COMBIN14(Spring)
▪Click'Add'
▪Select'Type3COMBIN14'.Click'OK'.
▪Enterthefollowinggeometricproperties:
SpringconstantK:
5
e.Inthe'ElementTypes'window,thereshouldnowbethreetypesofelementsdefined.
5.DefineElementMaterialProperties
a.Preprocessor>MaterialProps>MaterialModels
b.Inthe'DefineMaterialModelBehavior'Window,ensurethatMaterialModelNumber1isselected
c.SelectStructural>Linear>Elastic>Isotropic
d.Inthewindowthatappears,enterthegivethepropertiesofSteelthenclick'OK'.
Young'smodulusEX:
200000
Poisson'sRatioPRXY:
0.33
6.DefineNodes
Preprocessor>(-Modeling-)Create>Nodes>InActiveCS...
N,#,x,y,z
Wearegoingtodefine13Nodesforthisstructureasgiveninthefollowingtable(asdepictedbythecirclednumbersinthefigureabove):
Node
Coordinates(x,y,z)
1
(0,0,0)
2
(0,0,1000)
3
(1000,0,1000)
4
(1000,0,0)
5
(0,1000,1000)
6
(0,1000,0)
7
(700,700,500)
8
(400,400,500)
9
(0,0,0)
10
(0,0,1000)
11
(0,0,500)
12
(0,0,1500)
13
(0,0,-500)
7.CreatePIPE16elements
a.Defineelementtype
Preprocessor>(-Modeling-)Create>Elements>ElemAttributes...
Thefollowingwindowwillappear.Ensurethatthe'Elementtypenumber'issetto1PIPE16,'Materialnumber'issetto1,and'Realconstantsetnumber'issetto1.Thenclick'OK'.
b.Createelements
Preprocessor>(-Modeling-)Create>Elements>(-AutoNumbered-)ThruNodes
E,nodea,nodeb
CreatethefollowingelementsjoiningNodes'a'andNodes'b'.
Note:
becauseitisdifficulttographicallyselectthenodesyoumaywishtousethecommandline(forexample,thefirstentrywouldbe:
E,1,6).
Nodea
Nodeb
1
6
2
5
1
4
2
3
3
4
10
8
9
8
7
8
12
5
13
6
12
13
5
3
6
4
Youshouldobtainthefollowinggeometry(Obliqueview)
8.CreateCOMBIN7(Joint)elements
a.Defineelementtype
Preprocessor>(-Modeling-)Create>Elements>ElemAttributes
Ensurethatthe'Elementtypenumber'issetto2COMBIN7andthat'Realconstantsetnumber'issetto2.Thenclick'OK'
b.Createelements
Whendefiningajoint,threenodesarerequired.Twonodesarecoincidentatthepointofrotation.Theelementsthatconnecttothejointmustreferenceeachofthecoincidentpoints.Theothernodeforthejointdefinestheaxisofrotation.Theaxiswouldbethelinefromthecoincidentnodestotheothernode.
Preprocessor>(-Modeling-)Create>Elements>(-AutoNumbered-)ThruNodes
E,nodea,nodeb,nodec
CreatethefollowinglinesjoiningNode'a'andNode'b'
Nodea
Nodeb
Nodec
1
9
11
2
10
11
9.CreateCOMBIN14(Spring)elements
a.Defineelementtype
Preprocessor>(-Modeling-)Create>Elements>ElemAttributes
Ensurethatthe'Elementtypenumber'issetto3COMBIN7andthat'Realconstantsetnumber'issetto3.Thenclick'OK'
b.Createelements
Preprocessor>(-Modeling-)Create>Elements>(-AutoNumbered-)ThruNodes
E,nodea,nodeb
CreatethefollowinglinesjoiningNode'a'andNode'b'
Nodea
Nodeb
5
8
8
6
10.NOTE:
Toensurethatthecorrectnodeswereusedtomakethecorrectelementintheabovetable,youcanlistalltheelementsdefinedinthemodel.Todothis,selectUtilitiesMenu>List>Elements>Nodes+Attributes.
11.Meshing
Becausewehavedefinedourmodelusingnodesandelements,wedonotneedtomeshourmodel.Ifweinitiallydefinedourmodelusingkeypointsandlines,wewouldhavehadtocreateelementsinourmodelbymeshingthelines.ItistheelementsthatANSYSusestosolvethemodel.
12.PlotElements
UtilityMenu>Plot>Elements
Youmayalsowishtoturnonelementnumberingandturnoffkeypointnumbering
UtilityMenu>PlotCtrls>Numbering...
1.DefineAnalysisType
Solution>NewAnalysis>Static
ANTYPE,0
2.AllowLargeDeflection
Solution>Sol'nControls>basic
NLGEOM,ON
Becausethemodelisexpectedtodeformconsiderably,weneedtoincludetheeffectsoflargedeformation.
3.ApplyConstraints
Solution>(-Loads-)Apply>(-Structural-)>Displacement>OnNodes
oFixNodes3,4,12,and13.(ie-alldegreesoffreedomareconstrained).
4.ApplyLoads
Solution>(-Loads-)Apply>(-Structural-)>Force/Moment>OnNodes
oApplyaverticalpointloadof1000Natnode#7.
Theappliedloadsandconstraintsshouldnowappearasshowninthefigurebelow.
Note:
Tohavetheconstraintsandloadsappeareachtimeyouselect'Replot'inANSYS,youmustchangesomesettingsunderUtilityMenu>PlotCtrls>Symbols....Inthewindowthatappearschecktheboxbeside'AllAppliedBC's'inthe'BoundaryConditionSymbol'section.
5.SolvetheSystem
Solution>(-Solve-)CurrentLS
SOLVE
Note:
Duringthesolution,youwillseeayellowwarningwindowwhichstatesthatthe"Coefficientratioexceeds1.0e8".Thiswarningindicatesthatthesolutionhasrelativelylargedisplacements.Thisisduetotherotationaboutthejoints.
1.PlotDeformedShape
GeneralPostproc>PlotResults>DeformedShape
PLDISP.2
2.ExtractingInformationasParameters
Inthisproblem,wewouldliketofindtheverticaldisplacementofnode#7.WewilldothisusingtheGETcommand.
a.SelectUtilityMenu>Parameters>GetScalarData...
b.Thefollowingwindowwillappear.Select'Resultsdata'and'Nodalresults'asshownthenclick'OK'
c.Fillinthe'GetNodalResultsData'windowasshownbelow:
d.ToviewthedefinedparameterselectUtilityMenu>Parameters>ScalarParameters...
ThereforetheverticaldisplacementofNode7is323.78mm.Thiscanberepeatedforanyoftheothernodesyouareinterestedin.
TheaboveexamplewassolvedusingamixtureoftheGraphicalUserInterface(orGUI)andthecommandlanguageinterfaceofANSYS.ThisproblemhasalsobeensolvedusingtheANSYScommandlanguageinterfacethatyoumaywanttobrowse.Openthe.HTMLversion,copyandpastethecodeintoNotepadorasimilartexteditorandsaveittoyourcomputer.Nowgoto'File>Readinputfrom...'andselectthefile.A.PDFversionisalsoavailableforprinting.
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