陶瓷材料力学性能

陶瓷材料力学性能第一页，共二十九页，编辑于2023年，星期四•Tensilestress,s:•Shearstress,t:Stresshasunits:N/m2orlb/in2ENGINEERINGSTRESS第二页，共二十九页，编辑于2023年，星期四•Elasticmodulus,E•E~curvatureatroEislargerifEoislarger.PROPERTIESFROMBONDING:E第三页，共二十九页，编辑于2023年，星期四•ElasticShearmodulus,G:t=G

g•ElasticBulkmodulus,K:•Specialrelationsforisotropicmaterials:simpletorsiontestpressuretest:Init.vol=Vo.Volchg.=DVOTHERELASTICPROPERTIES第四页，共二十九页，编辑于2023年，星期四•Tensilestrain:•Lateralstrain:•Shearstrain:qStrainisalwaysdimensionless.(L)(-LL)ENGINEERINGSTRAIN第五页，共二十九页，编辑于2023年，星期四(c)2003Brooks/Cole,adivisionofThomsonLearning,Inc.ThomsonLearning™isatrademarkusedhereinunderlicense.Figure6.3(a)Tensile,compressive,shearandbendingstresses.(b)IllustrationshowinghowYoung’smodulusisdefinedforelasticmaterial.(c)Fornonlinearmaterials,weusetheslopeofatangentasavariablequantitythatreplacestheYoung’smodulusconstant第六页，共二十九页，编辑于2023年，星期四TheTensileTest:UseoftheStress-StrainDiagramLoad-Theforceappliedtoamaterialduringtesting.StraingageorExtensometer-Adeviceusedformeasuringchangeinlengthandhencestrain.Glasstemperature(Tg)-Atemperaturebelowwhichanotherwiseductilematerialbehavesasifitisbrittle.Engineeringstress-Theappliedload,orforce,dividedbytheoriginalcross-sectionalareaofthematerial.Engineeringstrain-Theamountthatamaterialdeformsperunitlengthinatensiletest.第七页，共二十九页，编辑于2023年，星期四(c)2003Brooks/Cole,adivisionofThomsonLearning,Inc.ThomsonLearning™isatrademarkusedhereinunderlicense.Figure6.7Aunidirectionalforceisappliedtoaspecimeninthetensiletestbymeansofthemoveablecrosshead.Thecross-headmovementcanbeperformedusingscrewsorahydraulicmechanism第八页，共二十九页，编辑于2023年，星期四(c)2003Brooks/Cole,adivisionofThomsonLearning,Inc.ThomsonLearning™isatrademarkusedhereinunderlicense.Figure6.9Tensilestress-straincurvesfordifferentmaterials.Notethatthesearequalitative第九页，共二十九页，编辑于2023年，星期四•Ductilefractureisdesirableforstructuralapplications!•Classification:Ductile:warningbeforefracture,i.e.changesgeometrybeforefailureBrittle:NowarningAdaptedfromFig.8.1,Callister6e.DUCTILEVSBRITTLEFAILURE第十页，共二十九页，编辑于2023年，星期四(c)2003Brooks/Cole,adivisionofThomsonLearning,Inc.ThomsonLearning™isatrademarkusedhereinunderlicense.Figure6.10Thestress-straincurveforanaluminumalloy第十一页，共二十九页，编辑于2023年，星期四1.Initial2.Smallload3.UnloadElasticmeansreversible!ELASTICDEFORMATION第十二页，共二十九页，编辑于2023年，星期四31.Initial2.Smallload3.UnloadPlasticmeanspermanent!PLASTICDEFORMATION(METALS)第十三页，共二十九页，编辑于2023年，星期四(c)2003Brooks/Cole,adivisionofThomsonLearning,Inc.ThomsonLearning™isatrademarkusedhereinunderlicense.Figure6.11(a)Determiningthe0.2%offsetyieldstrengthingraycastion,and(b)upperandloweryieldpointbehaviorinalow-carbonsteel第十四页，共二十九页，编辑于2023年，星期四TrueStressandTrueStrainTruestressTheloaddividedbytheactualcross-sectionalareaofthespecimenatthatload.TruestrainThestraincalculatedusingactualandnotoriginaldimensions,givenbyεtln(l/l0).Figure6.17Therelationbetweenthetruestress-truestraindiagramandengineeringstress-engineeringstraindiagram.Thecurvesareidenticaltotheyieldpoint第十五页，共二十九页，编辑于2023年，星期四TheBendTestforBrittleMaterialsBendtest-Applicationofaforcetothecenterofabarthatissupportedoneachendtodeterminetheresistanceofthematerialtoastaticorslowlyappliedload.Flexuralstrengthormodulusofrupture-Thestressrequiredtofractureaspecimeninabendtest.Flexuralmodulus-Themodulusofelasticitycalculatedfromtheresultsofabendtest,givingtheslopeofthestress-deflectioncurve.第十六页，共二十九页，编辑于2023年，星期四Figure6.18Thestress-strainbehaviorofbrittlematerialscomparedwiththatofmoreductilematerials第十七页，共二十九页，编辑于2023年，星期四Figure6.19(a)Thebendtestoftenusedformeasuringthestrengthofbrittlematerials,and(b)thedeflectionδobtainedbybending第十八页，共二十九页，编辑于2023年，星期四Figure6.21(a)Threepointand(b)four-pointbendtestsetup第十九页，共二十九页，编辑于2023年，星期四第二十页，共二十九页，编辑于2023年，星期四HardnessofMaterialsHardnesstest-Measurestheresistanceofamaterialtopenetrationbyasharpobject.Macrohardness-Overallbulkhardnessofmaterialsmeasuredusingloads>2N.MicrohardnessHardnessofmaterialstypicallymeasuredusingloadslessthan2NusingsuchtestasKnoop(HK).Nano-hardness-Hardnessofmaterialsmeasuredat1–10nmlengthscaleusingextremelysmall(~100µN)forces.第二十一页，共二十九页，编辑于2023年，星期四Figure6.23IndentorsfortheBrinellandRockwellhardnesstests第二十二页，共二十九页，编辑于2023年，星期四VickersHardness,Hv第二十三页，共二十九页，编辑于2023年，星期四FRACTURETOUGHNESSFracturetoughness:Kc=Ysc(pa)0.5=Y(2Egs)0.5

KcisamaterialpropertyY~1,dependsongeometry第二十四页，共二十九页，编辑于2023年，星期四increasingBasedondatainTableB5,Callister6e.Compositereinforcementgeometryis:f=fibers;sf=shortfibers;w=whiskers;p=particles.Additiondataasnoted(vol.fractionofreinforcement):1.(55vol%)ASMHandbook,Vol.21,ASMInt.,MaterialsPark,OH(2001)p.606.2.(55vol%)CourtesyJ.Cornie,MMC,Inc.,Waltham,MA.3.(30vol%)P.F.Becheretal.,FractureMechanicsofCeramics,Vol.7,PlenumPress(1986).pp.61-73.4.CourtesyCoorsTek,Go