週期性多孔金屬材料的熱流性能（簡體書）

《週期性多孔金屬材料的熱流性能》在揭示多功能超輕週期性多孔金屬材料和結構在強制對流條件下傳熱傳質機理，為研製以多功能超輕多孔材料為基本材料、具有優良傳熱性能和力學性能的高效緊湊式換熱器、微熱管等提供理論依據和指導。

Tian Jian Lu、Feng Xu、Ting Wen編寫的這本《周期性多孔金屬材料的熱流性能(英文版)》旨在揭示多功能超輕周期性多孔金屬材料和結構在強制對流條件下傳熱傳質機理，為研制以多功能超輕多孔材料為基本材料、具有優良傳熱性能和力學性能的高效緊湊式換熱器、微熱管等提供理論依據和指導。

Chapter1Introduction
1.1 IntroductionandSynopsis
Inlate1990s,drivenbytheneedsofminimizingmanufacturingandoperationalcostsinsatellites,arevolutionaryconcept―Multifunctionalstructures(MFS)―wasdeveloped,whichcombineselectroniccomponents(multi-chipmodules,orMCMs)andsignalandpowerdistributioncablingwithinaloadbearingstructurewithembeddedthermalcontrol.Thisdesignconceptdramaticallychangedthedesignapproachforspacesystems,andinaddition,ledtoaparadigmshiftinthedesignmethodologyofthestructuresandcontrolcommunity[1～4].
Signi.cante.ortsinincorporatingtheMFSconceptintomaterialsen-gineeringhaveledtoanentirelynewcategoryofmaterials:multifunctionalmaterials.Cellularsolidsareagroupofmaterialswithmultifunctionalattributes,whichhavetailorablestructurestoachievesystem-levelperfor-manceasmaterialsthatcombinemechanical,thermal,electrical,acoustical,andpossiblyotherfunctionalities.Recently,therehasbeenanincreasedinterestintheuseofcellularsolidsasmultifunctionalmaterialsfortworeasons[5]:(i)novelmanufacturingapproacheshavebene.ciallya.ectedperformanceandcost;(ii)higherlevelsofbasicunderstandingaboutme-chanical,thermal,andacousticpropertieshavebeendevelopedinconjunc-tionwithassociateddesignstrategies.
Multifunctionalityofcellularsolidsisaninterdisciplinaryresearchareathatrequiresaconcurrent-engineeringapproach.Theaimistoestablishstructure-propertyrelationshipsfortailoringmaterialstructurestoachievepropertiesandperformancelevelsthatarecustomizedforde.nedmultifunc-tionalapplications[6].Onesigni.cantapplicationareaisultralightmulti-functionalheatexchangersorheatsinksinlarge-scaleintegratedelectronicpackaging,wherecellularsolidsappeartobemoreattractivethanthecon-ventionalheatdissipationmediaastheheatdissipationmaterialisalsorequiredtosupportlargestructuralloads.Themultifunctionaldesignin-
2Chapter1Introduction
herentlyfacilitatestheincreaseofintegrationscale,whichresultsinincreas-ingpowerdensitiesinelectronicpackaging.Therefore,highlye.ectiveandrobustthermalmanagementviathesecellularsolidsiscrucial.Withtherequirementsoncapabilityofcarryingbothmechanicalandthermalloadsinmind,thechallengesaretoestablishrelationshipsbetweentopologyandproperties,andtooptimizethegeometricparametersapplicabletovariousthermo-mechanicalapplications[7～9].
1.2 CellularSolids
Cellularsolidsarede.nedasthosemadeupofaninterconnectednetworkofsolidstrutsorplatesthatformtheedgesandfacesofcells.Theyarefoundinmanynatural(wood,cork,sponge,bone,etc.)andman-madestructures.
Basically,therearetwobroadclassesofcellularsolids,asshowninFigure1.1:onewithastochasticstructureandtheotherwithaperiodicstructure[10～13].Cellularsolidswithstochasticstructuresaremainlyfoams,whichcanbefurtherclassi.edintotwotypesbasedontheirporestructure:open-cellfoamsandclosed-cellfoams,asshowninFigure1.2(a)and(b),respectively.Theformercontainporesthatareconnectedtoeachotherandformaninterconnectednetwork;whilethelatterdonothaveintercon-nectedpores.Cellularsolidswithperiodicstructuresarefoundinavarietyofstructures,amongwhichthemostfrequentlymentionedarethosewithlatticetrussstructures,asshowninFigure1.2(c),(d)and(e),andprismaticstructures,asshowninFigure1.2(f),(g)and(h).
Onemayarguethedi.erencebetweentheperiodicengineeringstructuresandthecellularmaterialswithperiodicstructures.Ashby[14] pointedoutthattheydi.erinoneimportantregard:thatofscale.Scaleoftheunit
1.2 CellularSolids3
4Chapter1Introduction
cellofcellularsolidsisoneofmillimetersormicrometers,anditisthisthatallowsthemtobeviewedbothasstructuresandasmaterials.Atonelevel,theycanbeanalyzedusingclassicalmethodsofmechanics,justasanyspaceframeisanalyzed.Butatanotherwemustthinkofthecellularstructuresnotonlyasasetofconnectedstruts,butasa‘material’initsownright,withitsownsetofe.ectiveproperties,allowingdirectcomparisonswiththoseoffullydense,monolithicmaterials.
Variouspropertiesofacellularsoliddependontwoseparatesetsofpa-rameters:thosedescribingthegeometricstructureofthecellularsolid,andthosedescribingthepropertiesofthematerialofwhichthecellularsolidismade.Inotherwords,forcellularsolidswithdi.erentstructuresordif-ferentmaterials,theunderlyingmechanismsgoverningstructure-propertyrelationshipscanbeverydi.erent.
1.3 PeriodicCellularSolids
Whilecommercialmetalfoamswithopencells,whicharetypicalstochas-ticcellularstructures,aregoodcompactheatexchangersandrelativelycheapwhenmadebysintering,theirload-bearingcapabilityismuchinfe-riortoperiodicstructureshavingthesameweight.Thisarisesbecausetheirdeformationundermechanicalloadingisdominatedbycellwallbendingasopposedtocellwallstretchinginmostperiodicstructures[18].Nonetheless,ascross-.owheatexchangerstheycanprovideahighthermalconductivitypathforheattransport,averyhighsurfaceareafordissipationintoacool-ing.uidlocatedintheporesandacontiguouspathforforcingthecoolantthroughthestructure.
Therapidadvanceinmanufacturingtechniquessuchaslithographyandrapidprototypinghasmadepossibletoconstructnewtypesofcel-lularmaterialswithperiodicmicrostructures.Thesecellularstructureshavethermalandstructuraladvantagesoverotherconventionalheatdissi-pationmediaandotherperformancecharacteristics[13,19～23].Theprecisecontroloftopologiesduringthemanufacturingstagedi.erentiatesthenewcellularmaterialsfromconventionalheatdissipationmedia.Awidevari-etyofprocess-routeshavebeendevelopedtomanufacturecellularmetalswithrelativedensitiesof1%～20%andcellsizesfrom100μmtoseveralcentimetres[12].
1.3.1 2Dperiodiccellularsolids
Two-dimensional(2D)cellularsolids,withthesimpleststructuresamon-
1.3 PeriodicCellularSolids5
gstdi.erentcellularsolids,aregenerallyselectedasthefundamentalgeom-etryformodellingmorecomplicatedcellularsolidssuchasfoams[24].Moreimportantly,certainstructuralandthermalpropertiesof2Dcellularsolidsaresuperiortothoseoffoamswithequivalentdensities[18].
2Dcellularsolidsarecomposedofatwo-dimensionalarrayofpolygonswhichpackto.llaplaneareasuchasthehexagonalcellsofabeehivehoneycomb[25].Anexampleofa2DcellularsolidisshowninFigure1.2(a).Itisobviousthat,topologically,2Dcellularsolidsareanisotropic.Twodirectionscanbede.nedin2Dcellularsolids:oneisnormalorlateraltothecellprincipalaxes,y-zplaneshowninFigure1.2(b),whichislateraldirection;theotherisparalleltothecellprincipalaxes,xdirectionshowninFigure1.2(c),whichisaxialdirection.
2Dcellularsolids,sometimes,areusedassandwichcorestoformasandwichpanel.Inthesecases,correspondingly,thesandwichpanelwithface-sheetsnormaltothecellprincipalaxes,asshowninFigure1.2(g),iscalledasandwichpanelwithaxialcoressincetheloads(mechanical,ther-mal,etc.)aregenerallynormaltotheface-sheetsandequivalentlyparalleltothecellprincipalaxes;andthesandwichpanelwithface-sheetsparalleltothecellprincipalaxes,asshowninFigure1.2(h),isnamedasasandwichpanelwithlateralcoresforsimilarreasons.
1.3.2 3Dperiodiccellularsolids
Forthree-dimensional(3D)cellularsolids,themostoftenusedislattice,suchastetrahedrallattice,pyramidallattice,Kagomelatticeandwoventextile,asshowninFigure1.2(c)～(e).
Thepotentialuseofametalweavecon.gurationasoneoftheperiodicmaterials,coupledwithanovelbondingschemetofabricateperiodiccel-lularstructureswasreportedbyTian[11].Diversedesignsofthistextilecon.gurationhavebeenattemptedandsomeofresultswerereportedbyLi&Wirtz[26] and Xu & Wirtz[27].Thetetrahedrallattice,asshowninFigure1.2(c),hasthreetrusseseachmeetingatafacesheetnode,whilethepyramidalstructurehasfourtrussesmeetingatafacesheetnode,asshowninFigure1.2(d).Bothtopologieshavedirectionswhicharenotobscuredfor.uid.ow:threeofthesechannelsinasinglelayerofthetetrahedralstructureandtwointhepyramidalsystem[17].Anotherexampleforthethree-dimensionalperiodicmaterialswasreportedbyHo.mann[28],referredtoasaKagometopology.Thebasictopologyissomewhatsimilartothatofthebankofcylinderarrays,showingstructuralandaerodynamicanisotropy,
6Chapter1Introduction
asshowninFigure1.2(e).
Otherlatticetrusstopologieshavealsobeenproposedbaseduponmanu-facturingconsiderations[17].Figure1.2(f)～(h)showsexamplesthatareeasytomakefromwires.Thediamondtextilestructureismadefromlayersofaplainweavemetalfabricthathavebeenbondedtoeachother.
1.4 MultifunctionalApplications
Wellestablisheddataonthemechanicalpropertiesofcellularsystemswitheitherperiodicorstochasticmicrostructuresdemonstratethattherel-ativelyhighsti.nessandyieldstrengthachievableatlowdensitycreatesanopportunityforlightweightstructures[5,29～33].Periodiccellularmet-alshavebeenexploitedformultifunctionalapplications[17].Forexample,some,suchashexagonalhoneycomb,arewidelyusedtoenablethedesignoflightweightsandwichpanelstructures[34],forcreatingunidirectional.uid.ows[35],forabsorbingtheenergyofimpacts[36],toimpedethermaltrans-portacrossthefacesofsandwichpanelsandforacousticdamping,forblastwavemitigation[37～39].
Inaddition,theopentopologieswithhighsurfaceareadensityhavethermalattributesthatmayenableapplicationswhichrequireastructureforheatdissipationaswellasmechanicalsti.ness/strength.Thestructureshaveahighsurfaceareadensityandmaybeconstructedoutofhighcon-ductivitymaterials.Thesecombinationsmakethecellularmaterialscapableheatdissipationmediathatcanbeusede.ectivelyforcoupledthermalandstructuralapplications,forexampleasajetblastde.ectoronanaircraftcarrier.Insuchanapplication,highmechanicalcompressionisexertedonthede.ectorplatewhenanaircraftrollsovertheretractedde.ectorandthensubsequentlyahighthermalloadfromthejetisappliedattake-o..Thejetblastde.ectorisinclinedatapproximately50. withrespecttothedecksurfaceduringtake-o..Inthissituation,thehotjetofsurfacetem-peraturewithradialvariationsimpingesthe.atplatethathasconvectioncoolingmechanismunderneathtocooltheplatedowntoacertainleveloftemperatureinashortperiodoftime.Toenhancethisconvectionheattransfer,avarietyofstructuredlattice-materialscanbeused.However,con-ventional.ntypeheatexchangersarenotsuitableduetothemechanicalloadings.
Whilstcommercialmetalfoamswithstochasticcellularmorphologiesareingeneralgoodcompactheatexchangersandrelativelycheap(ifpro-cessedviathesinteringroute),theyarenotstructurallye.cient,astheir