Ch20 - Materials Selection

CHAPTER20MaterialsSelectionThemanufacturerofthiscarbon-berreinforcedcompositebicycleusesasophisticatedsoftwarepackage[utilizing“niteelementanalysis”]toanalyzehowtheframewillrespondtostress,allowingtheengineerstotailortheframestiff-nesstotheindividualrider.(CourtesyofAlgor,Inc.)T.S.Y.S.ESpecificationsUNSnumber.A92036ChemicalComositionCompositionlimits.0.50maxSi;0.50maxFe;2.2maxCu;0.10to0.40Mn;0.30to0.6Mg;0.10maxCr;0.25maxZn;0.15maxTi;0.05maxothers(each);0.15maxothers(total);balAlApplicationsTypicaluses.SheetforautobodypanelsMechanicalPropertiesTensileproperties.Typical,for0.64to3.18mm(0.025to0.125in.)flatsheet,T4temper;tensilestrength,340MPa(49ksi);yieldstrength,195MPa(28ksi);elongation,24%in50mmor2in.Minimum,for0.64to3.18mmflatsheet,T4temper;tensilestrength,290MPa(42ksi);yieldstrength,160MPa(23ksi);elongation,20%in50mmor2in.Hardness.Typical,T4temper:80HR15Tstrain-hardeningexponent,0.23Elasticmodulus.Tension,70.3GPa(10.2×106ksi);compression,71.7GPa(10.4×106ksi)Fatiguestrength.Typical,T4temper:124MPa(18ksi)at107cyclesforflatsheettestedinreversedflexureFigure20-1Thebasicmechanicalpropertiesobtainedfromthetensiletestintro-ducedinChapter6leadtoalistofengineeringdesignparametersforagivenalloy.(TheparametersarereproducedfromalistinASMHandbook,Vol.2,ASMInternational,MaterialsPark,Ohio,1990.)MaterialpropertiesMaterialsscienceMaterialsengineeringStructureAtomicbondingCrystalstructureDefectstructureMicrostructureMacrostructureServiceperformanceStressesCorrosionTemperatureRadiationVibrationFigure20-2Schematicillustrationofthecentralroleplayedbypropertiesintheselectionofmaterials.Propertiesarealinkbetweenthefundamentalis-suesofmaterialsscienceandthepracticalchallengesofmaterialsengineer-ing.(FromG.E.Dieter,inASMHandbook,Vol.20:MaterialsSelectionandDesign,ASMInternational,MaterialsPark,Ohio,1997,p.245.)DesignServiceconditionsFunctionCostMaterialsPropertiesAvailabilityCostPropertiesEquipmentselectionInfluenceonpropertiesCostFigure20-3Schematicillustrationoftheintegralrelationshipamongmaterials,theprocessingofthosematerials,andengineeringdesign.(FromG.E.Dieter,inASMHandbook,Vol.20:Ma-terialsSelectionandDesign,ASMInternational,MaterialsPark,Ohio,1997,p.243.)EngineeringcompositesLowerElimitfortruesolidsWoodproductsWoodsParalleltograinPolymersfoamsYoungsmodulus,E(GPa)0.10.010.11.01010010000.31.03.01030EngineeringpolymersEngineeringalloysEngineeringceramicsPorousceramicsDiamondSialonsSiAluminasBeCorkPerpendiculartograinAshMELPCEpoxiesPMMAPVCHDPELDPEPTFENylonPolyestersPlasticizedPVCPUElastomersPSPPAshOakOakPinePineFirFirHardbutylSoftbutylSiliconeBalsaBalsaSpruceBMoAlloysWC-CoWalloysNialloysCualloysRock,stoneCement,concreteGlassesPotteryTialloysZnalloysTinalloysLeadalloysAlalloysMgalloysSteelsCFRPUni-plyKFRPGFRPCFRPLaminatesGFRPKFRPGeSiCBeOSi3N4ZrO2MODULUS-DENSITYMFA:88-91Figure20-4Amaterialspropertychartwithaglobalviewofrelativemateri-alsperformance.Inthiscase,plotsofelasticmodulusanddensitydata(onlogarithmicscales)forvariousmaterialsindicatethatmembersofthedif-ferentcategoriesofstructuralmaterialstendtogrouptogether.(AfterM.F.Ashby,MaterialsSelectioninEngineeringDesign,PergamonPress,Inc.,Elmsford,N.Y.,1992.)SailBattenBoardFinMastDaggerboardWishboneUniversaljointFigure20-5Componentsofawindsurferdesign.Thestiffnessofthemastcontrolsthesailshape,andthepivotingofthemastabouttheuniversaljointcontrolstheresponseofthecraft.(Af-terM.F.Ashby,“PerformanceIndices,”inASMHandbook,Vol.20:MaterialsSelectionandDesign,ASMInternational,MaterialsPark,Ohio,1997,pp.281–290.)EngineeringcompositesLowerElimitfortruesolidsWoodproductsWoodsParalleltograinPolymersfoamsYoungsmodulus,E(GPa)0.10.010.11.01010010000.31.03.01030EngineeringpolymersEngineeringalloysEngineeringceramicsPorousceramicsDiamondSialonsSiAluminasBeCorkPerpendiculartograinAshMELPCEpoxiesPMMAPVCHDPELDPEPTFENylonPolyestersPlasticizedPVCPUElastomersPSPPAshOakOakPinePineFirSpruceFirHardbutylSoftbutylSiliconeBalsaBalsaSpruceBMoAlloysWC-CoWalloysNialloysCualloysRock,stoneCement,concreteGlassesPotteryTialloysZnalloysTinalloysLeadalloysAlalloysMgalloysSteelsCFRPUni-plyKFRPGFRPCFRPLaminatesGFRPKFRPGeSiCBeOSi3N4ZrO2MODULUS-DENSITYMFA:88-91Figure20-6ThebehaviorofthewindsurfermastmaterialsinTable20.4aresu-perimposedonthelnEversuslnchartofFigure20–4normalizedbytheshapefactor,,ofathin-walledtube.Forexample,theCFRPmastwithashapefactorofD14:3isshownatapositionof.E=14:3;=14:3/rela-tivetothe.E;/positionofthebulkmaterialforwhichD1.(AfterM.F.Ashby,“PerformanceIndices,”inASMHandbook,Vol.20:MaterialsSelectionandDesign,ASMInternational,MaterialsPark,Ohio,1997,pp.281–290.)Figure20-7Adrivesprocketmadefromdispersion-toughenednylonhasre-placedaluminumandsteelpartsinmanymotocrossracingdesigns.(Cour-tesyoftheDuPontCompany,EngineeringPolymersDivision)StabilizertipsStabilizerfixedtrailingedgepanelsRudderElevatorsWingtobodyfairingFlapfairings(belowwing)LandinggeardoorsCowlcomponentsRadomeStrutfairingsUpperandlowerfixedleadingedgeAilerons(inboardandoutboard)Spoilers(inboardandoutboard)Upperandlowerfixedtrailinge