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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.