Mechanical Properties of Engineered Materials 2008 Part 15 potx

... Inc. AgreatdealofworkhasbeencarriedoutontheuseofSÀNcurves, andaconsiderableamountofusefuldatahasbeenaccumulatedonthe effectsofmeanstress,environment,notches,andotherfactors.Suchdata havebeenused,andarestillwidelyused,intheestimationofcomponent livesinengineeringstructures.However,theSÀNcurveisempiricalin nature,anditdoesnotprovideanyfundamentalunderstandingofthe underlyingfatigueprocessesinst...

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... Inc. 15. 6FUNCTIONALFORMSINTHEDIFFERENTCREEP REGIMES AsdiscussedinSec .15. 5,thefunctionalformsofthestrain–timerelation- shipsaredifferentintheprimary,secondary,andtertiaryregimes.Theseare generallycharacterizedbyempiricalormechanism-basedexpressions.This sectionwillfocusonthemechanism-basedmathematicalrelationships. Intheprimarycreepregime,thedependenceofcreepstrain,",ontime, t,hasbeen...

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... to Prof. Tom Eager and Prof. Nam Suh of MIT for inviting me to spend a sabbatical year as Visiting Martin Luther King Professor in the departments of Materials Science and Engineering and Mechanical ... Inc. 13.6Crack-TipBlunting 13.7CrackDeflection 13.8TwinToughening 13.9CrackTrapping 13.10MicrocrackShielding/Antishielding 13.11LinearSuperpositionConcept 13.12SynergisticTougheningConc...

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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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... 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. 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. givenbyEq.(6.5)foracubiclattice.Slipis,therefore,morelikelytooccur bytheexchangeofbonds,thanthecompleteshearofatomicplanesover eachother,assuggestedbyFig.6.1. Thereader...

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... Marcel Dekker, Inc. partialdislocationsisconfinedtoplanescontainingthestackingfaults, materialswithlowerstackingfaultenergies(wideseparationsofpartials) tendtoexhibithigherlevelsofstrainhardening(Table7.3). 7.8.6Superdislocations Sofar,ourdiscussionhasfocusedondislocationmotionindisordered structuresinwhichthesoluteatomscanoccupyanypositionwithinthe crystalstructure.However,insomeintermetallic...

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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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