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1、哈尔滨工业大学工程硕士学位论文AbstractMicroforminghaveadvantagesofmassproduction,highefficiency,lowcost,non-pollutingandnetshape,etc.ithasbecomeakeydirectionformicromanufacturingprocess.Withthereducedsizeoftheparts,plasticformingprocessexhibitsscaleeffectsdifferingfrommacroscopicforming,andt
2、heconventionalmaterialmodelisnolongerapplicable.Tostudymaterial’sanddiesize’sinfluenceonformingprocess,thisprojectcarrysoutmicrodeepdrawingusingT2purecopperfoil.Andamaterialmodelisconstructedbycombingcrystalplasticitytheoryandsurfacegrainmodel.Basedonthemodel,simulationofmicro
3、deepdrawingprocessiscarriedout.Detailsareasfollows:Thekineticformulasandtheconstitutiveformulasofcrystalplasticitymodelaredescribedandderived.Thennumericalsolverformulasbasedonimplicitintegrationarederivedandtwoleveliterativeprocessisusedtosolveiterativeequations.Thenmodelisim
4、plementedinUMATsubroutineofAbaqususingFortranlanguage.Usingthismodel,coppersinglecrystaltensionandcompressionprocesssimulationiscarriedout.Thesimulationresultsagreewellwiththeexperimentalresultsinliterature.Tensiletestiscarriedoutwithpurecopperfoilsthicknessofwhichare50μmto200
5、μmatastrainrateof1×10-3s-1.Afterannealing,yieldstrengthof50μmfoilsissignificantlylowerthanthatof200μmfoils,whichverifiesthescaleeffectthatflowstressreducewiththesizeofmaterialreducing.Bycombingthecrystalplasticityandsurfacegrainmodel,tensiletestsimulationisexecuted.Theresultre
6、flectsthescaleeffectcorrectlyandmaterialparametersaredetermined.Microdeepdrawingprocesswassimulatedusigmaterialmodelbuiltbefore.Accordingtotheprincipleofnon-dimensionaltheory,sameshapesbutdifferentsizesdrawingmodlesareconstructed.Andinfluenceofpuchradiusandfrictioncoefficient.
7、Resultsshowthatwiththeincreaseofpunchradius,maxdrawingloadreduces,andpunchstrokewheremaxloadappearsincreases.Drawingloadincreaseswithfrictioncoefficientincreasing.Whenscalefactordecreasesfrom2to0.5,themaxstrainandstressofdeformedcupsincreased,normalizeddrawingloaddecreasesbuts
8、econdnormalizedloadincreases.Basedontheprincipleofnon-dimensi
