Mechanical Properties of Engineered Materials 2008 Part 12 pps

... 11 FundamentalsofFractureMechanics 11.1INTRODUCTION Inthe17thcentury,thegreatscientistandpainter,LeonardodaVinci, performedsomestrengthmeasurementsonpianowireofdifferentlengths. Somewhatsurprisingly,hefoundthatthestrengthofpianowiredecreased withincreasinglengthofwire.Thislength-scaledependenceofstrengthwas notunderstooduntilthe20thcenturywhentheseriousstudyoffracturewas revisitedbyanumberofi...

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... Inc. Bibliography 11FundamentalsofFractureMechanics 11.1Introduction 11.2FundamentalsofFractureMechanics 11.3NotchConcentrationFactors 11.4GriffithFractureAnalysis 11.5EnergyReleaseRateandCompliance 11.6LinearElasticFractureMechanics 11.7Elastic–PlasticFractureMechanics 11.8FractureInitiationandResistance 11.9InterfacialFractureMechanics 11.10DynamicFractureMechanics 11.11Summary Bibliography 1...

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... treatment of the fundamen- tals of the mechanical behavior of materials. The text provides a rigorous review of the fundamental mechanics aspects of the mechanical behavior of materials. Shackleford, ... Inc. 1 Overview of Crystal/Defect Structure and Mechanical Properties and Behavior 1.1 INTRODUCTION The mechanical behavior of materials describes the response...

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... Inc. 3 BasicDefinitionsofStressandStrain 3.1INTRODUCTION Themechanicalpropertiesofmaterialsdescribetheircharacteristic responsestoappliedloadsanddisplacements.However,mosttextsrelate themechanicalpropertiesofmaterialstostressesandstrains.Itis,therefore, importantforthereadertobecomefamiliarwiththebasicdefinitionsof stressandstrainbeforeproceedingontotheremainingchaptersofthis book.However,thewe...

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... plastic deformation of solids are often controlled by the movem ent of defects. It is, therefore, important for the student of mechanical behavior to be familiar with the different types of defects that ... Hardness The hardness of a material is a measure of its resistance to penetration by an indenter. Hardness is also a measure of strength and often has the units of stress...

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... Inc. 5.2PHYSICALBASISFORPLASTICITY 5.2.1PlasticityinCeramics Mostceramicsonlyundergoonlyelasticdeformationpriortotheonsetof catastrophicfailureatroomtemperature.Hence,mostreportsonthe mechanicalpropertiesofceramicsareoftenlimitedtoelasticproperties. Furthermore,mostceramistsreportflexuralpropertiesobtainedunder three-orfour-pointbending.Typicalstrengthpropertiesofselectedceramic materialsarepr...

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... Inc. Cottrell, A.H. (1957) The Properties of Materials at High Rates of Strain. Institute of Mechanical Engineering, London, UK. Courtney, T.H. (1990) Mechanical Behavior of Materials, John Wiley, New ... Inc. therefore,appearstomovetotherightbyadistanceofonelatticespacing,b [Fig.6.9(b)]. Ifwecontinuetoapplyasufficientlyhighshearstresstothecrystal, dislocationmotionwillcontinu...

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... b 3 ð7:12aÞ or 1 2 ½ 110¼ 1 6 ½ 211þ 1 6 ½ 121 ð7:12bÞ The partial dislocations, b 2 and b 3 , are generally referred to as Shockley partials. They are formed because the elastic energies of the ... Marcel Dekker, Inc. partialdislocationsisconfinedtoplanescontainingthestackingfaults, materialswithlowerstackingfaultenergies(wideseparationsofpartials) tendtoexhibithigherlevelsofstrainharde...

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... Inc. isms,especiallywhenthenatureoftheparticleboundariespermitdisloca- tionentryintotheparticles,asshownschematicallyinFigs8.13(a)and 8.13(b)forcoherentandsemicoherentinterfaces(notethatcoherentinter- faceshavematchingprecipitateandmatrixatomsattheinterfaces,while semicoherentinterfaceshaveonlypartialmatchingofatoms).Incontrast, dislocationentry(intotheprecipitate)isdifficultwhentheinterfacesa...

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... Inc. usarefamiliarwithpolymermatrixcompositesthatareoftenusedinmod- erntennisracquetsandpolevaults.Wealsoknow,fromwatchingathletic events,thattheseso-calledadvancedcompositematerialspromotesignifi- cantimprovementsinperformance. Thischapterintroducestheconceptsthatarerequiredforabasic understandingoftheeffectsofcompositereinforcementoncomposite strengthandmodulus.Followingabriefdescriptionofth...

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