冪硬化材料三維斷裂力學的三參數(shù)理論.pdf

1、南京航空航天大學碩士學位論文冪硬化材料三維斷裂力學的三參數(shù)理論姓名：向目靖申請學位級別：碩士專業(yè)：工程力學指導(dǎo)教師：郭萬林201012冪硬化材料三維斷裂力學的三參數(shù)理論IIAbstractInaeronauticastronauticfieldsitisimptanttoaccuratelyassessingthestructure’scapacityfbearingload.Howeverthedamagetolerancemetho

2、dcurrentlyusedinengineeringapplicationisbasedonthetwodimensional(2D)fracturetheythenwecannotaccuratelypredictthedamagebehavisofthreedimensional(3D)structuresfromexperimentaldata.Basedonthe3Dfracturetheyfiniteelementanaly

3、seswemakeadeepanalysisofthe3DmodeIthroughthicknesscracktipstressfieldsfthepowerlawplasticitycreepingsolidsproposesimplifiedfmulationsfthetwoparametersolutionthreeparametersolutionfconvienentfengineeringapplicationbringup

4、anideatofurtherdevelopcriteriaf3Dfractureproblems.Themaincontentsareasfollows:1.Basedonthe3Dfacturetheyfcreepingsolidsbuiltbyourgroupweproceedtoinvestigatetherelationsbetweencracktipstrainfieldstimecracktipdisplacementfi

5、eldstimecracktipopeningdisplacementstime.WedrawconclusionsfromfiniteelementanalysesthattheC(t)Tztwoparametersolutioncanprovideefficientpredictionfthetensilestressontheligamentaheadofthecrackundersmallscalecreepconditions

6、whileunderextensivecreepconditionsathirdparameterQisnecessarytobeintroduced.Besidesweprovetheoutofplaneshearstressesbeingignedinthederivationisreasonable.2.Fromthe3Dfracturetheywecanseethattheactual3Dstateisatransitionst

7、atefromplanestraininthecracktiptoplanestressfarawayfromthetip.Butit’stoocomplicatedtobeappliedintheengineeringproblems.Hereweproposea“l(fā)ineartransition”fmfthepowerlawplasticitycreepingsolidstosimplifythetheeticalcalculati

8、onwhichisverifiedbythefiniteelementmethodsfitthevaryingparametersinappendix.Basedonthesimplified3DfracturetheywecomparetheJTztwoparametersolutionJTzQTthreeparametersolutionfthepowerlawplasticitysolidsindetailedfiniteelem

9、entanalysisgivethemodeIfracturecriteriafpowerlawplasticitysolidscreepcrackgrowthinasimplifiedfm.Keywds:C(t)TztwoparametersolutionC(t)TzQthreeparametersolutionlineartransitionfitJTztwoparametersolutionJTzQTthreeparameters