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1、萬方數(shù)據(jù)激光動(dòng)態(tài)柔性微彎曲成形尺寸效應(yīng)研究(3)尺寸效應(yīng)引起的材料不均勻塑性流動(dòng)在激光動(dòng)態(tài)柔性加載下得到一定的改善。激光沖擊區(qū)域材料發(fā)生明顯沖擊強(qiáng)化，材料原始晶界對(duì)塑性變形行為的影響減弱。實(shí)驗(yàn)中厚度309m箔板受高應(yīng)變率慣性效應(yīng)、晶粒細(xì)化機(jī)制作用呈現(xiàn)出超塑性變形行為，最大減薄率可達(dá)50％～60％。適當(dāng)提高激光能量可以使己粗化的表面凸起沿著模具型腔“削平”，避免材料發(fā)生局部頸縮，從而在一定程度上抑制了尺寸效應(yīng)現(xiàn)象。(4)利用LS．DYNA軟件對(duì)不同激光能量、不同厚度箔板的微彎曲成形過程進(jìn)行數(shù)值模擬分析，探究了激光沖擊軟模動(dòng)態(tài)加載下箔板的微彎曲變形歷程及微塑性變形規(guī)律。模擬分析了箔板的應(yīng)力
2、應(yīng)變分布、成形深度、減薄率分布，整體變化趨勢(shì)與實(shí)驗(yàn)結(jié)果基本一致。初步揭示激光動(dòng)態(tài)柔性微彎曲的四個(gè)成形階段：拉深階段、碰撞回彈階段、沖模階段、彈性恢復(fù)階段。關(guān)鍵詞：激光沖擊，金屬箔板，微彎曲成形，軟模，尺寸效應(yīng)，成形能力II萬方數(shù)據(jù)江蘇大學(xué)碩士學(xué)位論丈ABSTRACTMicroscalelaserdynamicforming(IxLDF)combinestheadvantagesoflasershockpeeningandhigh—speedforming，whichissuitableforhighstrengthand3Dcomplicatedshapeofmicroparts．It
3、greatlyincreasestheproductivityandimprovesfatiguepropertiesandformingabilityofformedparts．AlthoughtheformingmechanismofmicroscalelaserdyrmnicformingWasdifferentfromthetraditionalmicroforming，themechanicalpropertiesofmaterialsandplasticflowbehaviorshowscertainsizeeffect．Sizeeffecthasbecomearesear
4、chfocusinmicroformingfield．Inthisdissertation，themicroscalelaserdynamicfexibleforming，withrubberasthemediumofshockwave，isproposedbasedonthetheoryoflasershockandflexibleforming．Onthebasisoftheadvancedtechnology,theresearchofhighstrainrateformingmechanismandsizeeffectperformanceWascarriedout．Thema
5、inresearchworkandachievementsareasfollows：(1)Firstly,themicrobendingdiewithdifferentcharacteristicsizesismanufacturedandthelaserwithflatdistributionenergyisemployedtorealizelargeareamicrobendingofT2copperfoil．Inordertoquantitativelyinvestigatethecouplingeffectofgriansizeeffectandfeaturesizeeffec
6、t，theprocessparameterssuchasthefoilthickness(力，grainsize(回，featuresizeofmicrodie(叨ischangedtoobtainavarietyofN(Ⅳ_t／d)andMO仁w／t)values．TheformingdepthandfracturemodelischaracterizedtoindirectlyinvestigatetheeffectofNvalueandMvalueonmechanicalpropertiesofcopperfoil．ItWasfoundthatthemechanicalbehav
7、iorWasreducedwiththeincreasingNvalue．WhenN=0．4，theaxialdistributionofcrackWasappearedaroundthelocationofdiecorner．(2)ThesizeeffectphenomenainthedynamicdeformaionwithhighstainrateWasstudiedfromtheaspectsofsurfacemicroplasticd
