仪器压痕法断裂韧性检测方法.ppt

《仪器压痕法断裂韧性检测方法.ppt》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、EvaluationofFractureToughnessofMaterialsUsingInstrumentedIndentationTechnique:Ductile/BrittleFractureModels2013.08.30.WonJeJoContentsIntroductionIndentationFractureToughnessModels-BrittlefracturemodelDuctilefracturemodelVerificationoftheModelsComparisonbetweenfracturetestresul

2、tsandIITresultsApplicationsatlowtemperatureBasicconceptofindentationfracturetoughnessFracturetestCrackpropagationandfractureIndenterIITNocrackandnofractureIssueofindentationfracturetoughnessWhatisacorrelationbetweenfracturetestandIIT?Inthecaseofmetals,2Constrainteffectaheadofac

3、racktipPlasticregionconstrainedbyelasticregionbeneathanindenterSimilarconstrainteffect3R=250mIndenter[Material:APIX70]loadingConstrainteffect2.13.22.33.0TriaxialityofcracktipTriaxialityofindentationSENBIndentation4IndentationfracturetoughnessAnalogoussituation5Energyconcept=R

4、equiredenergyforcrackpropagationEquivalentfractureenergyinIndentationAnalysisofindentationprocess6IndentationprocessFormationofaplasticzonetothesurface7Formationofafully-developedplasticzone(c/aisconstant)Expansionofplasticzone(c/aincrease)cacaAssumptionOnsetofformationofafully

5、-developedplasticzone=Maximumstrainenergybeneaththeindenter≈Formationofequivalentfractureenergyh*8c/ahh*BrittlematerialsDuctilematerialsFracturesurfaceDeformationRelativelylittleornodeformationLargeplasticdeformationCriterionStresscontrolledcriticalfracturestressatthecracktip(s

6、f)Straincontrolledcriticalfracturestrainatthecracktip(ef)FormationoffractureenergyWhenstressreachedcriticalfracturestressWhenstrainreachedcriticalfracturestrainFractureBehavior9BrittleFractureModelDuctileFractureModelBrittleFractureModel10Criterion11Criticalindentationdepth(h*)

7、εrrCriticalstress(pressure)ath*CriterionAssumptionOnsetofformationtoafully-developedplasticzone=FormationofEquivalentfractureenergy12ApplicationofindentationtheoriesStep1Yieldingrightoutsidethecontactarea→FormationofaplasticzonetothesurfaceStep2Expansionoftheplasticzone→Formati

8、onoffully-developedplasticzonecah*13Hertzelasticcontac