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14.0Release
IntroductiontoANSYSMechanicalPart2
Workshop9ContactOffsetControl
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GoalsProblemstatement: Themodelconsistsofaworkbencharchivefilerepresentingavalveandpiston
assemblywithloadsapplied(seefigureonleft). Asthefigureontherightshows,agapexistsbetweenthepistonandbore(0.39mm). Ourgoalisto:
Solvethemodelasiswithnointerfacetreatment(resultswillbenonphysical). Solvethemodelasecondtimeusinganappropriateinitialcontactoffsettoclosethe
gap.
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ProjectSchematicBeginanewWorkbenchsessionand,fromtheProjectpage,chooseRestoreArchive...andbrowsetothefileWS9_Contact_Interface.wbpzandOpen(locationprovidedbyinstructor).Whenprompted,Saveusingthedefaultnameandthesamelocation.
FromtheUnitsmenuverify: ProjectunitsaresettoMetric(kg,mm,s,C,mA,N,mV). DisplayValuesinProjectUnitsischecked(on).
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...ProjectSchematic1. FromtheStaticStructuralsystemdouble
click(orRMB>Edit)theModelcell.
2. WhenMechanicalopens,verifytheunitsaresettoMetric(mm,kg,s,mV,mA).
2.
1.
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Preprocessing
3. Verifytheboundaryconditionsaresetasdescribedhere:
Force(20Nin+Y)appliedtotheendofthepistonshaft. Fixedsupportsappliedtothe4holesinthevalve. Remotedisplacementappliedtotheinsidefaceofthe
piston:
X=0 Y=Free
Z=
0
RotX =0 RotY =0 RotZ =Free 3.
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...Preprocessing4. Checkthecurrentcontactsettings:
Noticethecontacttypeisfrictionlessandthatnooffsethasbeenspecifiedintheformofaninterfacetreatment.
Allothersettingsareleftasdefault.
Recallthata0.39mmgapexistsbetweenthepistonandvalve. Withtheboundaryconditionsasset,weshouldexpectthepistontobeinitiallyfreeastheforceisapplied.
0.39mmGap
4.
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5. Solvethemodel:
Whenthesolutioncompletesamessageshouldindicatepossiblerigidbodymotionhasoccurred.
Aquickcheckofthemagnitudeoftotaldeformationshouldconfirmthemessage.
Amagnifieddeformationshowsthe2partshaveseparatedasexpected.
Solution
5.
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Background
Background:howwouldwefindthesizeofthegap? Onemethodistoselectthecircularlinesforthepistonandtheboreandrequestthe
SelectionInformation.
Fromtheinformationpanelwecansee8.89 8.5=0.39mmgap.
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...Background Background:howwouldwefindthesizeofthegap?
AsecondmethodistoinserttheContactToolattheConnectionsbranchandGenerateInitialContactResults.
TheinitialinformationshowsaGapof0.3851mm.
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Toaddressthegapinthecontactreturntothecontactdetails:6. IntheOffsetfieldenter0.39.
Verifythe
Interface
Treatment
is
set
to
Add
Offset,
NoRamping.
7. Resolvethemodel. Themodelshouldsolveinseveraliterations.
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8. Thedeformationandstressresultsnowappeartobereasonable.
TotalDeformation EquivalentStressonthevalve
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9. InserttheContactToolintotheSolutionbranch. ChecktheContactStatustoverifycontacthasbeenmaintained.
...Postprocessing
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Conclusions
Notes:
Theinitialsolutionverifiedthatrigidbodymotionwasoccurringwhenwetriedtoapplyaforcetopartswhichwereseparatedbyaninitialgap.
Wewereabletodeterminethegapsizeusing2differentmethodsinordertodeterminehowtoaddressthecontactproblem.
Withthegapsizeverified,weinputaninitialoffsetatthecontact,effectivelyclosingthegap.