柔性电子器件与制造：第4.1节柔性电子弯曲力学.pdf

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1、4.1BendingMechanicsChapterFlexibleElectronicsDevice&ManufacturingYongAnHuang,Ph.DFlexibleElectronicsResearchCenterSchoolofMechanicalScienceandEngineeringHuazhongUniversityofScienceandTechnologyOutline2First–FailureModeCausingtremendouslossindailylifeFailureModes3Columnscanfailiftheapplie

2、dloadexceedstheyieldstressofthematerial.ThisisastrengthfailureColumnscanalsofailbybuckling.ThisisastabilityfailureStrengthfailure4Strengthfailure5MechanicalfailureisdeterminedbytheweakestcomponentsofdevicesThecrackstrainofinorganicbrittlematerialisabout1-2%，andthemetalisalsobrokenaft

3、erneckingThefreestandingmetalfilmisdifferentfromfilm-on-substrateincrackingFracture6Moore,G.Electronics38,114–117(1965)FractureinmicrostructureVerticalstabilizer,whichseparatedTheS.S.SchenectadysplitfromAmericanAirlinesFlight587,apartbybrittlefracturewhileleadingtoafatalcrashinharbor(194

4、4)Fracture:utility7Stabilityfailure8Bucklingisaphenomenaofcompressionmembers.Oncethebucklingload,orcriticalload,isreached,thecolumnwillinstantlyloosestabilityand“kickout”tooneside.Oncebuckled,thecolumn’sabilitytocarryloadisgreatlyreduced.Buckling9Buckling10新西兰6.3级地震Stressed-outbehavior

5、s11StressAnxietyTensionPressureDepressionStressengineering:badsituations12DelaminationFatigueCrows-feetStriaegravidarumStressengineering:Beneficialapplications13Wrinkleandbuckleareubiquitousphenomena脱氢作用dehydrogenationNature419,579(2002)Phys.Rev.Lett.90,074302(2003)Bucklingpatternsof

6、AuonPDMS14Scriptamaterialia50,797(2004)NestedBucklingofArtificialSkin15Stiffskinoncompliantsubstrate:Auniversalmodel−Asaresultofageing,thesoftdermiscontracts,placingthesystemundercompressivestress.−HierarchicalwrinklingbyinternalstressNatureMaterials4,271(2005)NatureMaterials4,293(2005)F

7、oldableElectronicsonapliablesubstrate16Robustnessagainstbending,stretching,foldingNatureNanotechnology1,201-207(2008)BuckledSphere17CaoGuoxing,ChenXi,C.R.Li,Z.X.Cao,PRL100,2008Peel-Pick-Place18Mechanicsofflexibleelectronics19JohnA.Rogers:Mechanicsisthefutureofflex