资源描述：
《Fatigue limit and fatigue life prediction in high strength cold drawn eutectoid steel wires英文学习材料》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。
1、hu/~,?urfrwr.EyynpMorczr.S/ruc.rVol.I?,No.I,pp.3145.19898756-758X89$3.00+0.00PrintedinGreatBritain.AllrightsreservedCopyrighl(-1989FatigueofEngineeringMaterialsLidFATIGUELIMITANDFATIGUELIFEPREDICTIONINHIGHSTRENGTHCOLDDRAWNEUTECTOIDSTEELWIRESJ.LLORCAandV.SANCHEZ-GALVEZDe
2、partmentofMaterialsScience,ETSIngenierosdeCaminos,UniversidadPolitecnica.28040-Madrid,Spain(Receiwdin.finalfi~rni17May1988)Abstract-Boththefatiguelimitandthefatiguelifeofastructuralmemberarehighlydependentuponitssurfaceconditionandonthemicrocrackgrowthrate.Amodelbasedon
3、linearelasticfracturemechanicshasbeendevelopedwhichinvolvesbothparametersandpredictswithgoodaccuracytheavailableexperimentalresults.Thefactorsthatmustbemodifiedinordertoimprovethefatiguebehaviourofcolddrawneutectoidsteelwiresareindicated.NOMENCLATUREa=crackdepthc=surfac
4、ehalfcracklengthajc=aspectratioN=numberofcyclesda/dN=crackdepthgrowthratedc/dN=surfacecrackgrowthrateD=wirediameterCT,=yieldstressu;=failurestressCT~=fatiguelimitACT=stressrangeAK=stressintensityfactorrangeAKth=thresholdstressintensityfactorrangeR,=nominalstressratioR=s
5、tressintensityfactorratioA,=surfaceresidualstressA,,,=residualstressgradientrp=plasticzonesizeatcracktipINTRODUCTIONDuringthefatiguelifeofasmoothmetallicmember,threephysicallydifferentstagescanbedistinguished:firstly,thegenerationofasurfaceflaw;secondly,thepropagationof
6、suchaflaworcrackuptoacriticalsizeandfinally,theunstablegrowthofthecrackleadingtotheruptureofthemember.LinearElasticFractureMechanics(LEFM)haspermittedthecharacterizationofthebehaviourduringthetwolaststages,butsomedifficultieshaveariseninthecaseofcrackinitiation.Ontheoth
7、erhand,crackinitiationandcrackpropagationarephysicallydifferentphenomenaandthusthereisatransitionperiodbetweenthosestageswhereLEFMisnotalwaysvalid[l].Muchresearchhasbeencarriedouttostudysurfaceinitiationandpropagationofamicrocrack.Asaresult,manymodelshavebeenproposed[2-
8、6]thatmayexplainsomespecificexperimental3132J.LLORCAandV.SANCHEZ-GALVEZresults.Theyidentifiedthemechanicalandm
