计算机在材料科学中的应用上机实验八.docx

计算机在材料科学中的应用上机实验八.docx

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计算机在材料科学中的应用上机实验八

计算机在材料科学中的应用上机实验八

铸件凝固过程的分析（SolidificationofaCasting）

3.1.1.ProblemSpecification

∙ApplicableANSYSProducts:

 ANSYS/Multiphysics,ANSYS/Mechanical,ANSYS/ED

∙LevelofDifficulty:

 moderate

∙InteractiveTimeRequired:

 60to90minutes

∙Discipline:

 thermal

∙AnalysisType:

 nonlineartransient

∙ElementTypesUsed:

 PLANE55

∙ANSYSFeaturesDemonstrated:

 solidmodeling,conduction,convection,phasechange,selecting,solutioncontrol,time-historypostprocessing,useofa"getfunction"

∙ApplicableHelpAvailable:

 （NOTE:

Thecontentsoftheparticularhelptopicthatyouchoosewillappearinthisbrowserwindow,replacingtheinformationyouarenowreading.Whenyouarefinishedreadingthehelptopic,clickonthebrowser'sBackbuttontoreturntothistutorial.） ThermalAnalysisGuide-Chapter3.TransientThermalAnalysis,ElementsReference-PLANE55

3.1.2.ProblemDescription

Thisisatransientheattransferanalysisofacastingprocess. Theobjectiveistotrackthetemperaturedistributioninthesteelcastingandthemoldduringthesolidificationprocess,whichoccursoveradurationof4hours. ThecastingismadeinanL-shapedsandmoldwith4inchthickwalls. Convectionoccursbetweenthesandmoldandtheambientair.

Given

MaterialPropertiesforSand

Conductivity（KXX）

0.025Btu/（hr-in-oF）

Density（DENS）

0.054lb/in3

Specificheat（C）

0.28Btu/（lb-oF）

Conductivity（KXX）forSteel

at0oF

1.44Btu/（hr-in-oF）

at2643oF

1.54

at2750oF

1.22

at2875oF

1.22

Enthalpy（ENTH）forSteel

at0oF

0.0Btu/in3

at2643oF

128.1

at2750oF

163.8

at2875oF

174.2

InitialConditions

Temperatureofsteel

2875oF

Temperatureofsand

80oF

ConvectionProperties

Filmcoefficient

0.014Btu/（hr-in2-oF）

Ambienttemperature

80oF

ApproachandAssumptions

A2-Danalysisofaoneunitthickslicewillbeperformed. Halfsymmetryisusedtoreducethesizeofthemodel. Thelowerhalfistheportionmodeled.

Themoldmaterial（sand）hasconstantmaterialproperties. Thecasting（steel）hastemperature-dependentthermalconductivityandenthalpy;bothareinputinatableofvaluesversustemperature. Theenthalpypropertytablecapturesthelatentheatcapacityofthemetalasitsolidifies. Radiationeffectsareignored.

Solutioncontrolisusedtoestablishseveralnonlinearoptions,includingautomatictimestepping. Automatictimesteppingdeterminesthepropertimestepincrementsneededtoconvergethephasechangenonlinearity. Thismeansthatsmallertimestepsizeswillbeusedduringthetransitionfrommoltenmetaltosolidstate.

3.1.3.PrepareforaThermalAnalysis

改变工作文件名：

UtilityMenu>file>ChangeJobname>

Casting××××××

Newloganderrorfiles?

Yes

3.1.3.1.Step1:

Setpreferences.

ToSetPreferences:

1.MainMenu>Preferences

2.（check）“Individualdiscipline（s）toshowintheGUI”=Thermal

3.[OK]

3.1.4BuildGeometry

1. Definekeypoints.

Totakeadvantageofsymmetryinthisproblem,modelonlyhalfofthe"L." First,constructthetrapezoidrepresentingtheoutlineofthemoldbydefiningthefourcornerpointsofthetrapezoidandthendefininganareaconnectingthesefourkeypoints.

1.MainMenu:

 Preprocessor-Modeling-Create--Keypoints --InActiveCS

2.Enter1forkeypointnumber -»

3.Enter0,0,0forcoordinatelocations -»

4.Applytodefinekeypoint1（keypointwillbeat0,0,0） -»

5.Enter2forkeypointnumber -»

6.Enter22,0,0forcoordinatelocations -»

7.Applytodefinekeypoint2 -»

8.Enter3forkeypointnumber -»

9.Enter10,12,0forcoordinatelocations -»

10.Applytodefinekeypoint3 -»

11.Enter4forkeypointnumber -»

12.Enter0,12,0forcoordinatelocations -»

13.OK -»

Removetheglobaltriadsymbolsothatitwon'tobscuretheviewofthekeypointattheorigin.

14.UtilityMenu:

PlotCtrls --WindowControls --WindowOptions

15.SetlocationoftriadtoNotshown -»

16.OK -»

.

2. Createareasformoldandcasting.

Nowcreateanareaforthemoldbyconnectingthefourkeypoints.

1.MainMenu:

 Preprocessor-Modeling-Create-Areas-Arbitrary--ThroughKPs

2.Pickkeypoints1through4insequentialorder. Youcanseethelinesformasyoupick.

3.OKtocreatearea（inpickingmenu）

4.Toolbar:

 SAVE_DB

Tocreatetheareaforthecasting,"carveout"theareafromthefirstarea. Thisisdonebycreatingarectangleprimitive（don'tworryabouttheexactdimensionsontherightside;itcanbelongerthanitneedstobe）,overlappingtheareas（Booleanoperation）,andthendeletingtheextraneousarealeftover.

5.MainMenu:

 Preprocessor-Modeling-Create-Areas-Rectangle-ByDimensions

6.Enter4and22forX-coordinates -»

7.Enter4and8forY-coordinates -»

8.OK -»

9.UtilityMenu:

 PlotCtrls- Numbering

10.Turnonkeypointnumbers -»

11.Turnonareanumbers -»

12.OK -»

13.UtilityMenu:

 Plot- Areas

14.MainMenu:

 Preprocessor-Modeling-Operate-Booleans-Overlap-Areas

15.PickAlltochoosebothareasforoverlapping -»

16.MainMenu:

 Preprocessor-Modeling-Delete-AreaandBelow

17.Pickarea3

18.OK（inpickingmenu）todeletearea3

19.UtilityMenu>file>Saveas

Casting××××××geom.db

3.1.5.DefineMaterials

3.1.5.1.Step3:

Definematerialproperties.

Definethesandmoldmaterialpropertiesasmaterialnumber1.Thesearenotfunctionsoftemperature.

1.MainMenu>Preprocessor>MaterialProps>MaterialModels

2.（double-click）“Thermal”,then“Conductivity”,then“Isotropic”

3.“KXX”=0.025

4.[OK]

5.（double-click）“SpecificHeat”

6.“C”=0.28

7.[OK]

8.（double-click）“Density”

9.“DENS”=0.54

10.[OK]

Note

PCUsers:

YoucanviewademoondefiningonematerialmodelbypointingyourInternetExplorerbrowsertothefollowingURLaddress:

Themetalcastingisdefinedasmaterialnumber2.Thesepropertieschangesignificantlyasthemetalcoolsdownfromtheliquidphasetothesolidphase.Therefore,theyareenteredinatableofpropertiesversustemperature.

Firstdefinethetemperaturedependentthermalconductivity.

11.Material>NewModel

12.“DefineMaterialID”=2

13.[OK]

14.（double-click）“Isotropic”

15.[AddTemperature]threetimestocreatefieldsforthefourtemperatures.

16.“T1”=0

17.“T2”=2643

18.“T3”=2750

19.“T4”=2875

20.“KXX”at“T1”=1.44

21.“KXX”at“T2”=1.54

22.“KXX”at“T3”=1.22

23.“KXX”at“T4”=1.22

YouwillnowcopythefourtemperaturessoyouwillbeabletopastethemintotheEnthalpydialogbox.

24.Selectthetemperaturesbyholdingtheleftmousebuttonanddraggingacrossthetemperaturerowsothattherowishighlighted.

25.[Ctrl]then[c]tocopythetemperatures.

26.[OK]

Next,definethetemperaturedependententhalpy.

27.（double-click）“Enthalpy”

28.[AddTemperature]threetimestocreatefieldsforthefourtemperatures.

29.PastethetemperaturesintothedialogboxbyhighlightingtheT1temperaturefield,andpressing[Ctrl]then[v].

30.“ENTH”at“T1”=0

31.“ENTH”at“T2”=128.1

32.“ENTH”at“T3”=163.8

33.“ENTH”at“T4”=174.2

34.[OK]

Note

PCUsers:

YoucanviewademoonaddingatemperaturedependentmaterialmodelbypointingyourInternetExplorerbrowsertothefollowingURLaddress:

3.1.5.2.Step4:

Plotmaterialpropertiesvs.temperature.

1.（double-click）“Thermalconduct.（iso）”underMaterialModelNumber2.

2.[Graph]

3.[OK]

Note

PCUsers:

YoucanviewademoongraphingatemperaturedependentmaterialmodelbypointingyourInternetExplorerbrowsertothefollowingURLaddress:

4.（double-click）“Enthalpy”undertherightorleftwindow.

5.[Graph]

6.[OK]

7.Material>Exit

8.Toolbar:

SAVE_DB

3.1.5.3.Step5:

Defineelementtype.

YouwillnowdefinetheelementtypeasPLANE55.

1.MainMenu>Preprocessor>ElementType>Add/Edit/Delete

2.[Add...]

3.“ThermalSolid”（leftcolumn）

4.“Quad4node55”（rightcolumn）

5.[OK]

6.[Close]

7.UtilityMenu>file>Saveas

Casting××××××model.db

3.1.6.GenerateMesh

3.1.6.1.Step6:

Meshthemodel.

1.UtilityMenu>Plot>Areas

SpecifyaSmartSizeof4.ThiswillallowaslightlyfinermeshthanthedefaultandyettheresultingnumberofelementswillbewithintheANSYSEDprogramlimitsforthemaximumnumberofelements.

2.MainMenu>Preprocessor>Meshing>MeshTool

3.（check）“SmartSize”

4.（slide）“FineCourse”=4

5.[Mesh]

Meshthemoldareafirst.Notethatthematerialattributereferencenumberdefaultsto1andthereisnoneedtosetattributesbeforemeshingthearea.

6.PickthemoldareaA5（Hint:

PlacethemousecursorontopoftheA5labelwhenyoupick--thisisthepicking"hotspot,"basedonthecentroidofthearea.）.

7.

[OK]

Beforemeshingthecastingarea,setthematerialattributetothatofsteel（material2）.

8.（dropdowninMeshTool）“ElementAttributes”=Global,then[Set]

9.（dropdown）“Materialnumber”=2

10.[OK]

11.UtilityMenu>Plot>Areas

12.[Mesh]inMeshTool

13.PickareaA4

14.[OK]

15.[Close]inMeshTool

16.UtilityMenu>Plot>Elements

Note:

Themeshyouobtainmayvaryslightlyfromthemeshshownhere.Asaresultofthis,youmayseeslightlydifferentresultsduringpostprocessing.Foradiscussionofresultsaccuracy,seePlanningYourApproachintheANSYSModelingandMeshingGuide.

Toverifythattheelementshavetherightmaterials,plotthemwithdifferentcolorsfordifferentmaterials.

17.UtilityMenu>PlotCtrls>Numbering

18.（dropdown）“Elem/Attribnumbering”=Materialnumbers

19.[OK]

Note:

theelementsofmat