Metal Inelasticity in ABAQUS(ABAQUS金属非线性).ppt

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1、DuctileMetalResponseOverviewUniaxialTestatLowTemperaturesStressandstrainmeasuresYieldStrainreversalafteryieldCyclicloadingNeckingTemperatureandstrain-ratedependenceUniaxialTestatElevatedTemperatures2MetalInelasticityinABAQUSUniaxialTestatLowTemperaturesAuniaxia

2、ltest,whenperformedintensionorcompressionatarelativelylowtemperature(belowtwo-thirdsofthemetal’smeltingtemperatureonanabsolutescale),exhibitsseveralphenomenathatarebasictotheformulationoftheclassicaltheoriesofmetalplasticity.Atypicalresponseisshowninthefigurebe

3、low:Typicaluniaxialstress-straincurveforametalstressBAAstrain3MetalInelasticityinABAQUSUniaxialTestatLowTemperaturesStressandstrainmeasuresTheresultsareplottedasstressversusstrain.Becausenominalstrainsof20%–100%arepossibleintensionfortypicalmetalsatroomtempera

4、ture,aprecisedefinitionofstrainisneeded.Thedominantmicromechanicalmechanismforductilityinpolycrystallinematerialsisdislocationmotion.Themechanismdrivingdislocationmotionistheforce,orresolvedstress,associatedwiththedislocationmechanism.Thus,theimportantstressmea

5、sureonthemicroscopicscaleisthetrue(orCauchy)stress:theforceperunitofcurrentareatransmittedacrossasurfaceinthematerial.4MetalInelasticityinABAQUSUniaxialTestatLowTemperaturesDatafromtensionandcompressiontestscorrespondwhentruestressisadoptedonthemacroscaleandthe

6、conjugatelogarithmicstrainmeasureisused.Truestresssandlogarithmicstraineareconjugateinthesensethatse=workperunitvolume.Tensionandcompressionstress-straincurvesforcopper:experimentaldatafromLudwikandScheu,fromHill(1950)Tensileorcompressivestressinkg/mm2Percentag

7、ereductioninarea(tension)orpercentagereductioninheight(compression)353025201050155102025301535TensionCompression5MetalInelasticityinABAQUSUniaxialTestatLowTemperaturesYielddatashouldalwaysbegiveninABAQUSastruestressversuslogarithmicstrain.Logarithmicstrain,e,is

8、definedaswherelisthecurrentgaugelength,l0istheoriginalgaugelength,andenomistheengineeringornominalstrain.Truestress,s,isdefinedaswheresnomistheengineeringornominalstress(sno