mechanics of materials and interfaces

1、ChrakantS.DesaiMechanicsofMaterialsInterfacesTheDisturbedStateConceptBocaRatonLondonNewYkWashingtonD.C.CRCPress?2001ByCRCPressLLCThisbookcontainsinfmationobtainedfromauthentichighlyregardedsources.Reprintedmaterialisquot

2、edwithpermissionsourcesareindicated.Awidevarietyofreferencesarelisted.Reasonableefftshavebeenmadetopublishreliabledatainfmationbuttheauththepublishercannotassumeresponsibilityfthevalidityofallmaterialsftheconsequencesoft

3、heiruse.Neitherthisbooknanypartmaybereproducedtransmittedinanyfmbyanymeanselectronicmechanicalincludingphotocopyingmicrofilmingrecdingbyanyinfmationstageretrievalsystemwithoutpripermissioninwritingfromthepublisher.Thecon

4、sentofCRCPressLLCdoesnotextendtocopyingfgeneraldistributionfpromotionfcreatingnewwksfresale.SpecificpermissionmustbeobtainedinwritingfromCRCPressLLCfsuchcopying.DirectallinquiriestoCRCPressLLC2000N.W.CpateBlvd.BocaRatonF

5、lida33431visitourwebsiteatTrademarkNotice:Productcpatenamesmaybetrademarksregisteredtrademarksareusedonlyfidentificationexplanationwithoutintenttoinfringe.?2001byCRCPressLLCNoclaimtoiginalU.S.GovernmentwksInternationalSt

6、ardBookNumber084930248XLibraryofCongressCardNumber00052883PrintedintheUnitedStatesofAmerica1234567890PrintedonacidfreepaperLibraryofCongressCataloginginPublicationDataDesaiC.S.(ChrakantS.)1936–Mechanicsofmaterialsinterfa

7、ces:thedisturbedstateconceptbyChrakantS.Desaip.cm.Includesbibliographicalreferencesindex.ISBN084930248X(alk.paper)1.Strengthofmaterials—Mathematicalmodels.2.Strainsstresses.3.Interfaces(Physicalsciences)I.Title.TA405.D45

8、2000620.1′12′015118—dc2100052883Tomyfather?whoIbelieveisinquisitivequestioninginthespacebeyondwhichiscongruenttothatofmine.Tothosegiants?ofmechanicsphysicsphilosophyonwhosecontributionswestextend.ContinuumdiscontinuumPoi

9、ntsspacesExisttogetherUnitedCoupledSatAsatExistencenonexistenceExisttogetherUnitedCoupledMergingineachother.?2001ByCRCPressLLCPREFACEUnderstingacterizingthemechanicalbehaviofengineeringmaterialsinterfacesjointsplayvitalr

10、olesinthepredictionofthebehavitheanalysisdesignofengineeringsystems.Principlesofmechanicsphysicsareinvokedtoderivegoverningequationsthatallowsolutionsfthebehaviofthesystems.Suchclosedfmnumericalsolutionsinvolvetheimptant

11、componentofmaterialbehavidefinedbyconstitutivelawsequationsmodels.Definitionoftheconstitutivelawsbasedonfundamentalprinciplesofmechanicsidentificationofsignificantparametersdeterminationoftheparametersfromappropriate(lab

12、atyfield)testsvalidationofthemodelswithrespecttothetestdataimplementationofthemodelsinthesolutionprocedures—closedfmcomputational—validationofpracticalboundaryvalueproblemsareallimptantingredientsinthedevelopmentuseofrea

13、listicmaterialmodels.Theacterizationofthemechanicalbehaviofengineeringmaterialscalledthestress–strainconstitutivemodelshasbeenthetopicunderthegeneralsubjectof“mechanicsofmaterials”.Asmaterialbehaviisveryoftennonlinearthe

14、governingequationsarealsononlinear.Intheearlystageshoweveritwasnecessarytolinearizethegoverningdifferentialequationssothattheclosedfmsolutionprocedurescouldbeused.Theadventoftheelectroniccomputerwithincreasingstagecapaci

15、tyspeedmadeitpossibletosolvenonlinearequationsindiscretizedfms.Hencetheneedtoassumeconstantcoefficientsmaterialparametersinthelinearclosedfmsolutionsmaynolongerexist.Asaconsequenceitisnowpossibletodevelopusemodelsfrealis

16、ticnonlinearmaterialresponse.Almostallmaterialsexhibitnonlinearbehavi.Insimplewdsthisimpliesthattheresponseofthematerialisnotproptionaltotheinputexcitationload.Hencealthoughtheassumptionoflinearityprovidedstillcanprovide

17、usefulsolutionstheirvalidityishighlylimitedinthenonlinearregimesofthematerialresponse.Thusthefactthatmoderncomputersnumericalcomputationalmethodsnowpermittheconsiderationofnonlinearresponsesisindeedahighlydesirabledevelo

18、pment.AmonglinearconstitutivemodelsareHooke’slawthatdefineslinearelasticstress–strainresponseundermechanicalloadDarcy’slawthatdefinesthelinearvelocitygradientresponseffluidflowOhm’slawthatdefinesthelinearvoltagecurrentre

19、lationfelectricalflow.Itisrecognizedthatthevalidityofthesemodelsislimited.Hooke’slawdoesnotapplyifthematerialresponseinvolveseffectoffactssuchasstateofstressstrainstressloadingpathstemperatureinitialinduceddiscontinuitie

20、sexistence?2001ByCRCPressLLCoffluidgasinthematerial’spousmicrostructure.Darcy’slawdoesnotapplyiftheflowisturbulentOhm’slawlosesvalidityiftheconductingmaterialisnonhomogeneousthermaleffectsarepresent.Ftheacterizationofthe

21、nonlinearbehaviofmaterialstheeffectsofsignificantfactssuchasinitialconditionsstateofstressstressloadingpathtypeofloadingmultiphasenatureneedtobeconsideredfrealisticengineeringsolutions.Thepursuitofthedevelopmentofmodelsf

22、thenonlinearresponsehasalonghistyinthesubjectsofphysicsmechanicsofmaterials.Amongthemodelsproposeddevelopedarelinearnonlinearelasticity(e.g.hyperhypoelasticity)classicalplasticity(vonMisesTrescaMohr–CoulombDrucker–Prager

23、)continuoushardeningyieldingplasticity(criticalstatecaphierarchicalsinglesurface–HISS)kinematicanisotropichardeninginthecontextofthetheyofplasticity.Viscoelasticviscoplasticelastoviscoplasticmodelsareamongthosedevelopedt

24、oaccountftimedependentviscouscreepresponse.Endochronictheyinvolvinganimplicittimescalehasbeenproposedinthecontextofplasticityviscoplasticity.Modelsbasedonmicromechanicalconsiderationsinvolvetheideathattheobservedmacrolev

25、elresponseofthematerialcanbeobtainedbyintegratingtheresponsesofbehaviatthemicroparticleleveloftenthroughaprocessoflinearintegration.Althoughthisideaiselegantatthistimeitsuffersfromthelimitationthattheparticlelevelrespons

26、eisdifficulttomeasureacterize.Mostofthemodelsarebasedontheassumptionthatthematerialiscontinuous.Asaresultthetheiesofcontinuummechanicshavebeeninvokedftheirfmulation.Itisrecognizedhoweverthatdiscontinuitiesexistdevelopina

27、defmingmaterial.Thusthetheiesbasedoncontinuummechanicsmaynotbestrictlyvalidvariousmodelsbasedonfracturecontinuumdamageconceptstherebybecomerelevant.Theclassicalcontinuumdamagemodelsarebasedontheideathatamaterialexperienc

28、esmicrocrackingfracturingwhichcancausedegradationdamageinthematerial’sstiffnessstrength.Theremainingdegradedstiffness(strength)isthendefinedonthebasisoftheresponseoftheundamagedpartmodifiedbygrowingdamagedpartswhichareas

29、sumedtoactlikevoidspossessnostrengthatall.Asaresulttheclassicalcontinuumdamagemodelsdonotallowfthecouplinginteractionbetweenthedamagedundamagedparts.Thisaspecthassignificantconsequencesastheeffectofneighbing(damaged)part

30、sisnotincludedintheacterizationoftheresponse.Variousnonlocalmicrocrackinteractionmodelshavebeenproposedinthecontextoftheclassicaldamagemodel.Anobjectiveherehasbeentodevelopconstitutiveequationsthatallowfthecouplingbetwee

31、nthedamaged(microcracked)undamagedpartstheeffectofwhathappensintheneighbhoodofamaterialpoint.SuchenhancementsasgradientCosseratmicropolartheieshavebeenproposedtoincpatethenonlocaleffects.?2001ByCRCPressLLCTheeffectsoftem

32、peratureotherenvironmentalfactsareincporatedbydevelopingseparatetheiesbyexpressingtheparametersintheabovemodelsasfunctionsoftemperatureotherenvironmentalfacts.Thefegoingmodelsareusuallyrelevantfaspecificacteristicofthema

33、terialbehavisuchaselasticplasticcreepmicrocrackingfracture.Eachmodelinvolvesasetofparametersfaspecificacteristicthatneedstobedeterminedfromlabatytests.Thereisagrowingrecognitionthatdevelopmentofunifiedintegratedconstitut

34、ivedeionscanleadtomeefficienteconomicalsimplifiedmodelswitheaseofimplementationinsolutionprocedures.Asaresultanumberofefftshavebeenmadetowardunifiedhierarchicalmodels.Theapproachpresentedinthisbookrepresentsoneoftheseuni

35、fiedconcepts:thedisturbedstateconcept(DSC).TheDSCisaunifiedmodellingapproachthatallowsinanintegratedmannerfelasticplasticcreepstrainsmicrocrackingfractureleadingtosofteningdamagestiffeninghealinginasingleframewk.Itshiera

36、rchicalnaturepermitstheadoptionuseofspecializedversionsfthefegoingfacts.Asaresultitsdevelopmentapplicationaresimplifiedconsiderably.TheDSCisbasedonthebasicphysicalconsiderationthattheobservedresponseofamaterialcanbeexpre

37、ssedintermsoftheresponsesofitsconstituentsconnectedbythecouplingdisturbancefunction.Insimplewdstheobservedmaterialstateisconsideredtorepresentdisturbancedeviationwithrespecttothebehaviofthematerialfappropriatelydefinedre

38、ferencestates.Thisapproachisconsistentwiththeideathatthecurrentstateofamaterialsystemanimateinanimatecanbeconsideredtobethedisturbedstatewithrespecttoitsinitialfinalstate(s).InthecaseofengineeringmaterialstheDSCstipulate

39、sthatatanygivendefmationstagethematerialiscomposedoftwo(me)parts.Finstanceadrydefmingmaterialiscomposedofmaterialpartsintheiginal(continuum)statecalledtherelativelyintact(RI)stateremainingpartsinthedegradedstiffenedstate

40、calledthefullyadjusted(FA)statethemeaningsoftheterms“RIFAstate”willbeexplainedinsubsequentchapters.Thedegradedpartcanrepresenteffectsofrelativeparticlemotionsmicrocrackingduetothenaturalselfadjustment(SA)ofparticlesinthe

41、material’smicrostructurecanleadtodamagedegradation.Underfactssuchaschemicaltemperaturefluideffectsthemicrostructuremayexperiencestiffeninghealing.AlthoughthedegradationdamageaspectintheDSCissimilartothatintheclassicaldam

42、agemodelsthebasicframewkoftheDSCisgeneralsignificantlydifferentfromthatofthedamageconcept.IfamaterialelementiscomposedofmethanonematerialtheDSCcanbefmulatedftheoverallobservedresponse(ofthecomposite)bytreatingthebehaviof

43、individualcomponentsasreferenceresponses.ThebehaviofanindividualcomponentmaybeacterizedbyusingacontinuumtheybytreatingitasamixtureoftheRIFAparts.?2001ByCRCPressLLCDetailsoftheDSCincludingfmulationofequationsidentificatio

44、nofmaterialparametersdeterminationofparametersfrom(labaty)testsvalidationatthelabatyteststageimplementationinsolution(computer)proceduresvalidationsolutionofpracticalboundaryvalueproblemsarepresentedinthisbook.Comparison

45、sbetweentheDSCotheravailablemodelsarediscussedincludingtheadvantagestheDSCoffers.ThelatterariseduetoacteristicssuchasthecompactunifiednatureoftheDSCphysicalmeaningsofmaterialparametersconsiderablereductionintheregression

46、curvefittingrequiredinmanyothermodelseaseofdeterminationofparameterseaseofimplementationinsolutionprocedures.OneoftheDSC’sadvantagesisthatitcanbeusedf“solid”materialsfinterfacesjoints.Thelatterplayanimptantroleinthebehav

47、iofmanyengineeringsystemsinvolvingcombinationsoftwomematerials.Theyincludecontactsinmetalsinterfacesinsoilmedium(structure)problemsjointsinrockjointsinelectronicpackagingsystems.ItisshownthatthemathematicalframewkoftheDS

48、Cfthreedimensionalsolidscanbespecializedfthebehaviofmaterialcontactsidealizedasthinlayerzoneselements.ThefactthattheDSCallowsfinteractioncouplingbetweentheRIFApartsoffersanumberofadvantagesinthatthenonlocaleffectsareincl

49、udedinthemodelhencealsotheacteristicdimension.TheDSCdoesnotrequireconstitutivedeionofparticlelevelprocessesasthemicromechanicalmodelsdo.Theinteractingbehaviofthematerialcomposedofmillionsofparticlesisexpressedintermsofth

50、ecoupledresponsesofthematerialparts(clusters)intheRIFAparts.TheresponseoftheRIFApartscanbedefinedfromlabatytests.ThustheDSCeliminatestheneedfdefiningparticlelevelbehaviwhichisdifficulttomeasureatthistime.Atthesametimeita

51、llowsfthecoupledmicrolevelprocesses.ThebehaviofmaterialpartsinthereferencestatesintheDSCcanbedefinedonthebasisofanysuitablemodel(s).Oftensuchavailablecontinuumtheiesaselasticityplasticitythecriticalstateconceptareinvoked

52、ftheacterizations.TheDSCrepresentsacontinuousevolutioninthepursuitofthedevelopmentofconstitutivemodelsbytheauthhiscowkers.AlthoughitinvolvesanumberofnewinnovativeideastheDSCalsoreliesontheavailabletheiesofmechanicsthecon

53、tributionsofmanypeoplewhohavebeenthegiantsinthisfield.FinstancetheDSCincludesideasconceptsfromtheavailableelasticityplasticityviscoplasticitydamagefracturecriticalstatetheies.AstheDSCallowsadoptionoftheseavailablemodelsa

54、sspecialcasestheyarepresentedindividuallyinseparatechapterswithidentificationoftheiruseintheDSC.InsummarytheDSCisconsideredtorepresentauniquepowerfulmodellingproceduretoacterizethebehaviofawiderangeofmaterials?2001ByCRCP