材料成形力學(xué)雙語(yǔ)課件

材料成形力學(xué)

（雙語(yǔ)教學(xué)）MechanicsofMaterialFormingTheContentsoftheSubject1Introduction(引言)2StressAnalysis（應(yīng)力分析）3StrainAnalysis（應(yīng)變分析）4YieldCriteriaforDuctileMetals（塑性材料的屈服準(zhǔn)則）5Stress-StrainRelation（應(yīng)力－應(yīng)變關(guān)系）6StressEvaluationApproch-SlabMethod（工程法）7PlainStrainSlip-lineFieldTheory（平面應(yīng)變滑移線場(chǎng)理論）8ExtremumPrincipleforaRigidPerfectlyPlasticMaterial

（剛塑性材料的極限分析原理）Chapter1Introduction1)Elasticandplasticdeformation(彈性變形和塑性變形)A)ElasticdeformationForce(small)(力)StressState(應(yīng)力狀態(tài))Deformation(strain)(變形或應(yīng)變)Stress-Strain:linear(線性的)Deformation:recoverable（變形）

reversibleElasticdeformationTheoryofelasticity(elasticdeformedbody)(彈性理論)（彈性變形體）1.1DefinitionandscopeofthesubjectB)PlasticdeformationStress-Strain:non-linear(非線性的)Deformation:irrecoverable(不可恢復(fù)的)（變形）irreversiblePlasticdeformationTheoryofPlasticity(塑性理論)2)TheoryofPlasticity(塑性理論)Itisconcernedwiththemathematicalstudyofstressandstraininaplasticallydeformedbody.塑性理論主要考慮塑性變形體內(nèi)應(yīng)力－應(yīng)變的數(shù)學(xué)關(guān)系。Object（研究對(duì)象）Researchmethod（研究方法）Ductilemetalmaterials(塑性金屬材料)，independentoftime.ExperimentalobservationMacroscopicbehaviour.FormulizationItisdifferentfrommaterialscience.PhysicalexplanationMicroscopestructureCombineTheoryofplasticityMaterialscienceUnifiedtheoryofplasticityOurtask

3)NatureofEngineeringPlasticity(工程塑性理論的特性)Practiceandapplication（實(shí)踐和應(yīng)用）ToconstructrelationbetweenstressandstrainformetalsandtheiralloysTodevelopmathematicaltechnique,determinestressdistributionandpredictplasticdeformationTwoaimsFeaturesComplexstressstateNon-linearMath.difficultiesAssumptionsapproximations1864.TrescaYieldcriterion1.2BriefhistoricalaccountH.E.Trescacarriedoutexperimentsofmetalformingsuchaspunching,extrusionandcompressionusingsomemetals,andmeasuredtherelationbetweenformingloadandramdisplacement.HepresentedaseriesofpaperstotheFrenchAcademyofSciences,firstin1864.InFig.4thecross-sectionofanextrudedbilledmadeof20leadsheetsisgiven.Trescawasinterestedinthemetalflowassuggestedbythetitleofhisfirstpaper,(Ontheflowofsolidbodysubjectedtohighpressure),notyieldinginmaterialtesting.TrescaassumedthattheextrusionforcePcouldbeexpressedintermsoftheshearstressk,andestimatedthevalueofkfromthemeasuredformingloadofvariousprocesses.Becausethevaluesofshearstresskestimatedfromtheformingloadsdroppedinacertainrange,heconcludedthatthemetalflowoccurredunderaconstantmaximumshearstress.Saint-VenantandLévy1.2BriefhistoricalaccountWhenTrescapresentedhispapertotheFrenchAcademyofSciences,BarrédeSaint-Venant(1797–1886)wastheauthorityofmechanicsinFrancewhowaselectedamemberoftheAcademyin1868.AfterreadingtheexperimentalresultsofplasticflowbyTresca,hisattentionwasdrawntotheareaofplasticity.In1871,hewroteapaperonelastic-plasticanalysisofpartlyplasticproblems,suchastwistingofrod,bendingofrectangularbeamandpressurizingofhollowcylinder.Saint-Venantassumedthat(1)thevolumeofmaterialdoesnotchangeduringplasticdeformation,(2)thedirectionsofprincipalstrainscoincidewiththoseoftheprincipalstresses(nowknownastotalstraintheory),(3)themaximumshearstressateachpointisequaltoaspecificconstantinplasticregion.1.2Briefhistoricalaccount1.2BriefhistoricalaccountProgressofresearchinyieldcondition1.2Briefhistoricalaccount1.2Briefhistoricalaccount1920.PrandtlandHencky.Theoryofsliplinefield1.2BriefhistoricalaccountLudwigPrandtl（1870–1953）receivedengineeringeducationattheMunichTH.Aftergraduating,heremainedattheschoolasanassistantofA.F?ppl,andcarriedoutdoctoralworkonbendingofcircularplates.Afterworkingintheindustryforawhile,hewasappointedasaprofessorofindustrialmechanicsofHannoverTHin1900.Thereheproposedmembraneanalogyoftorsionandboundarylayeroffluidflow.In1904hewasinvitedtotheInstituteofMechanicsinG?ttingenUniversity.Soonhebegantostudyplasticitysuchasplasticbucklingandbending.Hewasappointedtheleaderofthelaboratoryofaerodynamics,andstudiedwingtheoremandotherimportantworksoffluiddynamics.In1922Prandtlestablishedthesocietyofappliedmathematicsandmechanics,“Gesellschaft

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MathematikundMechanik”,andledtheareaofappliedmechanics.Heisalsofamousastheteacherofmanyleadersinmechanicsinthe20thcenturysuchasTh.vonKármán(CaliforniaInstituteofTechnology),S.P.Timoshenko(StanfordUniversity),A.Nádai(WestinghouseLaboratory),W.Prager(BrownUniversity)andothers.1.2Briefhistoricalaccount1.2Briefhistoricalaccount1.2Briefhistoricalaccount1.2Briefhistoricalaccount1.2Briefhistoricalaccount1925.Von-Karman.Slabmethodapplytorolling1.2Briefhistoricalaccount1.2Briefhistoricalaccount1.2BriefhistoricalaccountChapter1Introduction1)AccordingtothehomologoustemperatureTHthehomologoustemperatureTheabsolutetesttemperature(實(shí)驗(yàn)時(shí)的絕對(duì)溫度)Theabsolutemeltingtemperature(絕對(duì)熔點(diǎn)溫度)Hotmetalformingprocesses（熱加工）Coldmetalformingprocesses（冷加工）Intermediate:Warmmetalformingprocesses（溫加工）1.3Classificationofmetalformingprocesses2)AccordingtothetypeofstressstateCompressivestressstate(predominant)Squeezinggroup（壓應(yīng)力狀態(tài)類）UpsettingClosedieforgingForging（鍛造）Extrusion（擠壓）ForwardBackwardPunch(沖頭)Work-piece(工件)Rolling（軋制）TensilestressstateDrawinggroup（拉應(yīng)力狀態(tài)類）s1s2s3Drawingofsheet,tube,barandwire.Fs1s2s3Deepdrawing.s1s2s3Dendinggroup（彎曲類）Tensilestressstateononeside.Compressio