计算机在材料科学中的应用上机实验八Word格式.docx
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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
Enthalpy（ENTH）forSteel
0.0Btu/in3
128.1
163.8
174.2
InitialConditions
Temperatureofsteel
2875oF
Temperatureofsand
80oF
ConvectionProperties
Filmcoefficient
0.014Btu/（hr-in2-oF）
Ambienttemperature
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.
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>
Saveas
Casting×
geom.db
3.1.5.DefineMaterials
3.1.5.1.Step3:
Definematerialproperties.
Definethesandmoldmaterialpropertiesasmaterialnumber1.Thesearenotfunctionsoftemperature.
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]
YoucanviewademoonaddingatemperaturedependentmaterialmodelbypointingyourInternetExplorerbrowsertothefollowingURLaddress:
3.1.5.2.Step4:
Plotmaterialpropertiesvs.temperature.
1.（double-click）“Thermalconduct.（iso）”underMaterialModelNumber2.
2.[Graph]
YoucanviewademoongraphingatemperaturedependentmaterialmodelbypointingyourInternetExplorerbrowsertothefollowingURLaddress:
4.（double-click）“Enthalpy”undertherightorleftwindow.
5.[Graph]
6.[OK]
7.Material>
Exit
8.Toolbar:
SAVE_DB
3.1.5.3.Step5:
Defineelementtype.
YouwillnowdefinetheelementtypeasPLANE55.
ElementType>
Add/Edit/Delete
2.[Add...]
3.“ThermalSolid”（leftcolumn）
4.“Quad4node55”（rightcolumn）
5.[OK]
6.[Close]
7.UtilityMenu>
model.db
3.1.6.GenerateMesh
3.1.6.1.Step6:
Meshthemodel.
1.UtilityMenu>
Plot>
SpecifyaSmartSizeof4.ThiswillallowaslightlyfinermeshthanthedefaultandyettheresultingnumberofelementswillbewithintheANSYSEDprogramlimitsforthemaximumnumberofelements.
2.MainMenu>
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
11.UtilityMenu>
Areas
12.[Mesh]inMeshTool
13.PickareaA4
14.[OK]
15.[Close]inMeshTool
16.UtilityMenu>
Elements
Note:
Themeshyouobtainmayvaryslightlyfromthemeshshownhere.Asaresultofthis,youmayseeslightlydifferentresultsduringpostprocessing.Foradiscussionofresultsaccuracy,seePlanningYourApproachintheANSYSModelingandMeshingGuide.
Toverifythattheelementshavetherightmaterials,plotthemwithdifferentcolorsfordifferentmaterials.
17.UtilityMenu>
PlotCtrls>
Numbering
18.（dropdown）“Elem/Attribnumbering”=Materialnumbers
19.[OK]
theelementsofmat
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