constitutive equations-plasticity.pdf

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1、MCEN5023/ASEN5012Chapter9ConstitutiveEquations-PlasticityFall,20061ConstitutiveEquationsMechanicalPropertiesofMaterials:¾ModulusofElasticity¾Tensilestrength¾YieldStrength¾Compressivestrength¾Hardness¾Impactstrength¾Creep2ConstitutiveEquationsMechanicalPropertiesofMaterials:Force

2、Extension3ConstitutiveEquationsMechanicalPropertiesofMaterials:Timedependent,ratedependentForceExtension4ConstitutiveEquationsMechanicalPropertiesofMaterials:StressStresstimetimeStrainStraintimetimeElasticityViscoelasticity5ConstitutiveEquationsMechanicalPropertiesofMaterials:Vi

3、scoelasticityCreepRelaxationStressStresstimetimeStrainStraintimetime6ConstitutiveEquationsPlasticDeformationinMaterialsLoadElongation7ConstitutiveEquationsPhysicsofplasticityofmetalsSometypicalcrystalstructureofmetalsBodyCenteredCubicFaceCenteredCubicHexagonalclose-packed(b.c.c)

4、(f.c.c)(h.c.p)8ConstitutiveEquationsPhysicsofplasticityofmetals9ConstitutiveEquationsPhysicsofplasticityofmetals-DefectsLinedefects10ConstitutiveEquationsPhysicsofplasticityofmetals-DislocationsEdgedislocationScrewdislocation11ConstitutiveEquationsPhysicsofplasticityofmetals-Dis

5、locationsFromedgedislocationtoscrewdislocations12ConstitutiveEquationsPhysicsofplasticityofmetals-MotionofdislocationsEdgedislocationsScrewdislocations13ConstitutiveEquationsPhysicsofplasticityofmetals-MotionofdislocationsProfessorHideharuNakashimaKyushuUniversity,Japan14Constit

6、utiveEquationsPhysicsofplasticityofmetals-HardeningHardeningisduetoobstaclestothemotionofdislocations;obstaclescanbeparticles,precipitations,grainboundaries.15ConstitutiveEquationsPhysicsofplasticityofmetals-HardeningThreetypesofhardeningmechanismSolidsolutionhardeningPrecipitat

7、ionhardeningStrainhardening16ConstitutiveEquationsPhysicsofplasticityofmetals-YieldσσyisyieldstrengthσyQuestion:howcanrelatetheσyfrom1Dtesttoyieldinageneral3Dstressstate?0.2%eAsimpletensiontest17ConstitutiveEquationsPhysicsofplasticityofmetals-YieldCriteriaIthasbeenfoundexperime

8、ntally1.Trescayieldcondition(1864)1τ=σ−σ≤τShear