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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... 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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... 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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