Composite-Materials

CompositeMaterialsR.LindekeENGR2110Introduction•ACompositematerialisamaterialsystemcomposedoftwoormoremacroconstituentsthatdifferinshapeandchemicalcompositionandwhichareinsolubleineachother.Thehistoryofcompositematerialsdatesbacktoearly20thcentury.In1940,fiberglasswasfirstusedtoreinforceepoxy.•Applications:–Aerospaceindustry–SportingGoodsIndustry–AutomotiveIndustry–HomeApplianceIndustryAdvancedAerospaceApplication:LearFan2100“all-composite”aircraftAdvancedAerospaceApplication:Boeing767(andin777,787airplanesw/thelatest,fullwingboxiscomposite):•Composites:--Multiphasematerialw/significantproportionsofeachphase.•Dispersedphase:--Purpose:enhancematrixproperties.MMC:increasesy,TS,creepresist.CMC:increaseKcPMC:increaseE,sy,TS,creepresist.--Classification:Particle,fiber,structural•Matrix:--Thecontinuousphase--Purposeisto:-transferstresstootherphases-protectphasesfromenvironment--Classification:MMC,CMC,PMCmetalceramicpolymerReprintedwithpermissionfromD.HullandT.W.Clyne,AnIntroductiontoCompositeMaterials,2nded.,CambridgeUniversityPress,NewYork,1996,Fig.3.6,p.47.Terminology/Classificationwovenfiberscrosssectionview0.5mm0.5mmCompositeStructuralOrganization:thedesignvariationsCompositeSurveyLarge-particleDispersion-strengthenedParticle-reinforcedContinuous(aligned)AlignedRandomlyorientedDiscontinuous(short)Fiber-reinforcedLaminatesSandwichpanelsStructuralCompositesAdaptedfromFig.16.2,Callister7e.•CMCs:IncreasedtoughnessCompositeBenefitsfiber-reinfun-reinfparticle-reinfForceBenddisplacement•PMCs:IncreasedE/rE(GPa)G=3E/8K=EDensity,r[mg/m3].1.3131030.01.1110102103metal/metalalloyspolymersPMCsceramicsAdaptedfromT.G.Nieh,Creepruptureofasilicon-carbidereinforcedaluminumcomposite,Metall.Trans.AVol.15(1),pp.139-146,1984.Usedwithpermission.•MMCs:Increasedcreepresistance20305010020010-1010-810-610-46061Al6061Alw/SiCwhiskerss(MPa)ess(s-1)CompositeSurvey:Particle-I•Examples:AdaptedfromFig.10.19,Callister7e.(Fig.10.19iscopyrightUnitedStatesSteelCorporation,1971.)-Spheroiditesteelmatrix:ferrite(a)(ductile)particles:cementite(Fe3C)(brittle)60mmAdaptedfromFig.16.4,Callister7e.(Fig.16.4iscourtesyCarboloySystems,Department,GeneralElectricCompany.)-WC/Cocementedcarbidematrix:cobalt(ductile)particles:WC(brittle,hard)Vm:5-12vol%!600mmAdaptedfromFig.16.5,Callister7e.(Fig.16.5iscourtesyGoodyearTireandRubberCompany.)-Automobiletiresmatrix:rubber(compliant)particles:C(stiffer)0.75mmParticle-reinforcedFiber-reinforcedStructuralCompositeSurvey:Particle-IIConcrete–gravel+sand+cement-Whysandandgravel?SandpacksintogravelvoidsReinforcedconcrete-Reinforcewithsteelrebarorremesh-increasesstrength-evenifcementmatrixiscrackedPrestressedconcrete-remeshundertensionduringsettingofconcrete.Tensionreleaseputsconcreteundercompressiveforce-Concretemuchstrongerundercompression.-AppliedtensionmustexceedcompressiveforceParticle-reinforcedFiber-reinforcedStructuralthreadedrodnutPosttensioning–tightennutstoputunderrodundertensionbutconcreteundercompression•Elasticmodulus,Ec,ofcomposites:--twoapproaches.•Applicationtootherproperties:--Electricalconductivity,se:ReplaceEintheaboveequationswithse.--Thermalconductivity,k:ReplaceEinaboveequationswithk.AdaptedfromFig.16.3,Callister7e.(Fig.16.3isfromR.H.Krock,ASTMProc,Vol.63,1963.)CompositeSurvey:Particle-IIIlowerlimit:1Ec=VmEm+VpEpcmmupperlimit:E=VE+VpEp“ruleofmixtures”Particle-reinforcedFiber-reinforcedStructuralData:Cumatrixw/tungstenparticles020406080100150200250300350vol%tungstenE(GPa)(Cu)(W)CompositeSurvey:Fiber•Fibersthemselvesareverystrong–Providesignificantstrengthimprovementtomaterial–Ex:fiber-glass•Continuousglassfilamentsinapolymermatrix•Strengthduetofibers•PolymersimplyholdstheminplaceandenvironmentallyprotectsthemParticle-reinforcedFiber-reinforcedStructuralFiberLoadingEffectunderStress:•Criticalfiberlength(lC)foreffectivestiffening&strengthening:•Ex:Forfiberglass,afiberlength15mmisneededsincethislengthprovidesa“Continuousfiber”basedonusualglassfiberpropertiesCompositeSurvey:FiberParticle-reinforcedFiber-reinforcedStructuralcfds15lengthfiberfiberdiametershearstrengthoffiber-matrixinterfacefiberstrengthintension•Why?Longerfiberscarrystressmoreefficiently!Shorter,thickerfiber:cfds15lengthfiberLonger,thinnerfiber:PoorerfiberefficiencyAdaptedfromFig.16.7,Callister7e.cfds15lengthfiberBetterfiberefficiencys(x)s(x)FiberLoadBehaviorunderStress:*l2fccdsCompositeSurvey:Fiber•FiberMaterials–Whiskers-Thinsinglecrystals-largelengthtodiameterratio•graphite,SiN,SiC•highcrystalperfection–extremelystrong,strongestknown•veryexpensiveParticle-reinforcedFiber-reinforcedStructural–Fibers•polycrystallineoramorphous•generallypolymersorceramics•Ex:Al2O3,Aramid,E-glass,Boron,UHMWPE–Wires•Metal–steel,Mo,WFiberAlignmentalignedcontinuousalignedrandomdiscontinuousAdaptedfromFig.16.8,Callister7e.BehaviorunderloadforFibers&MatrixCompositeStrength:LongitudinalLoadingContinuousfibers-Estimatefiber-reinforcedcompositestrengthforlongcontinuousfibersinamatrix•Longitudinaldeformationsc=smVm+sfVfbutec=em=efvolumefractionisostrainEce=EmVm