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附录A外文翻译－原文部分Studyofdelaminationindrillingcarbonfiberreinforcedplastics(CFRP)usingdesignexperimentsJ.P.Davim*,PedroReisDepartmentofMechanicalEngineering,UniversityofAveiroCampusSantiago,3810-193Aveiro,PortugalAbstractInthispaperispresentedanewcomprehensiveapproachtoselectcuttingparametersfordamage-freedrillingincarbonfiberreinforcedepoxycompositematerial.TheapproachisbasedonacombinationofTaguchi_stechniquesandontheanalysisofvariance(ANOVA).Aplanofexperiments,basedonthetechniquesofTaguchi,wasperformeddrillingwithcuttingparametersprefixedinanautoclavecarbonfiberreinforcedplastic(CFRP)laminate.TheANOVAisemployedtoinvestigatethecuttingcharacteristicsofCFRP_susinghighspeedsteel(HSS)andCementedCarbide(K10)drills.TheobjectivewastoestablishacorrelationbetweencuttingvelocityandfeedratewiththedelaminationinaCFRPlaminate.Thecorrelationwasobtainedbymultiplelinearregression.Finally,confirmationtestswereperformedtomakeacomparisonbetweentheresultsforeseenfromthementionedcorrelation._2002ElsevierScienceLtd.Allrightsreserved.Keywords:Drilling；Carbonfiberreinforcedplastics；Delaminationfactor；Taguchi_stechniques；Analysisofvariance.1.IntroductionOwingtothegrowinguseofcompositematerials,specificallythefiberreinforcedplastics(FRP)outsidethedefenceindustryandtheaerospaceindustry,theunitcostreplacestheperformanceatanycostasthemainconcernforproduction.So,theproductiontechnologies,especiallythemachiningofcomposites,areassumingamoreandmoresignificantroleastheyconditiontheeconomicviabilityoftheproduct.Machiningcompositematerialsisarathercomplextaskowingtoitsheterogeneity,heatsensitivity,andtothefactthatreinforcementsareextremelyabrasive.Conventionalmachiningmethodsshouldbeadaptedinsuchawaythattheydiminishthermalandmechanicaldamage.Drillingisafrequentlypracticedmachiningprocessinindustryowingtotheneedforcomponentassemblyinmechanicalpiecesandstructures.Thedrillingoflaminatecompositematerialsissignificantlyaffectedbythetendencyofthesematerialstodelaminateandthefiberstobondfromthematrixundertheactionofmachiningforces(thrustforceandtorque).Manyauthors[1–3],whenreportingaboutthedrillingoflaminatedcompositematerialsbyconventionaltools,haveshownthatthequalityofthecutsurfacesisstronglydependentonthedrillingparameters,toolgeometryandtoolmaterial.Aninappropriatechoiceoftheseparameterscanleadtounacceptablematerialdegradation,suchasfiberpull-out,matrixcratering,thermal江苏大学毕业设计1damageanddelamination.Amongthedefectscausedbydrilling,delaminationappearstobethemostcritical.Laminatedfiberreinforcedply_sundermachiningforcesaresubjecttotheriskofinterlaminarcrackpropagation,calleddelamination.Koenigetal.,studiedin1985themachiningoffiberreinforcedplasticsandconcludedthatahighfeedrateofdrillingwillcauseacrackaroundtheexitedgeofthehole[4].Millerpresentedin1987adatabaseonoptimumcuttingparametersfordrillingholeswithminimumlocalmachiningdamage[5].HochengandPuw[1],in1992presentedastudyofthechipformationandassessesthemachinabilityoftwocompositematerials(Thermoset-basedandThermoplastics-based)andconcludedthatfromcuttingchipstheformerpresentsalargeamountofdeformationinchipformation,whilethelattertendstofracture.Healsonoticedthatcarbon/ABSissuperiortocarbon/epoxyforsurfacequalityandbothholeedges.ChambersandBishop[6]in1995investigatedtheeffectofthecuttingparametersondrillingcarbon/epoxyandcarbon/peekandconcludedthatthedrillingofcarboncompositesisdependentuponthecharacteristicsofthematrixandthehelicalPCDdrillgeometrygavethebestoverallperformance.Inadditiontotheproblemsoftoolwear,itisverydifficulttoachievethequalityofsurfaceneededfortheaccurateassemblyofcomponentsinmechanicalstructures.Linetal.[7]in1996,carriedoutastudyondrillingofcarbonfiberreinforcedcompositeathighspeedandconcludedthatanincreaseofthecuttingvelocityleadsaincreasingofthedrillwear.Inthiswaythefactofincreasingthewearofdrillcausesarisingofthrustforce.Wen-ChouChen[3]in1997studiedthevariationsofcuttingforceswithorwithoutonsetdelaminationduringthedrillingoperationsandconcludedthatthedelamination-freedrillingprocessesmaybeobtainedbytheproperselectionsoftoolgeometryanddrillingparameters.Piquetetal.[8]in2000carriedoutastudyofdrillingthincarbon/epoxylaminateswithtwotypesofdrills,ahelicaldrillandadrillofspecialgeometry,andconcludedthatbothdrillsleadsadamageattheentranceinthewallandtheexitofthehole,withtheexceptionofspecialgeometrydrillwhichispossibleasignificantreductioninthefinaldamage.Enemuohetal.[9]in2001,realizethatwiththeapplicationofthetechniqueofTaguchiandothermethods,werepossibletoachievethecuttingparametersthatallowedtheabsenceofdamageinthedrillingoffiberreinforcedplastics.Alltheaboveworkscontributestothepracticeofcuttingcompositematerials,buttheydonotshowthebasicmechanismsofcutandthecharacterizationofthemachinability.2.Experimentalprocedure2.1.Meansandmaterials许静波：干燥机（组）设计2Inordertoachievetheobjectiveofthisexperimentalwork,mainlytheestablishingofcorrelationsbetweenthecuttingconditionswiththedelamination,machiningissueswereeffectuatedwithdifferentcuttingconditions,andwereusedcarbonfiberreinforcedplastics(CFRP_s)(Epoxymatrixreinforcedwith55%ofcarbonfiber)fortests.Thiscompositematerialwasproducedbyautoclavewithafiberorientationof0/90degrees,aswecanobserveonFig.1.Theexperimentshadbeencarriedoutinanautoclavelaminatemadeupof16layersoffiberswith4mmofthickness,usingthreedifferenttypesof5mmdiameterdrillspresentedintheFig.2.Ahelicalflutehighspeedsteel(HSS)drill(R415.5-0500-50-8C0),afour-flutecementedcarbide(K10)drill(R950.01H10F)andfinallyahelicalfluteK10carbidedrill(R415.5-0500-30-AC0),accordingtoISO1832.Adrillingmachinewith2,2kWspindlepowerandamaximumspindlespeedof2500rpmwasusedtoperformtheexperiments.Theuseddrillshavean118_pointangle.Thesqueezeofthelaminate,inthepressofjawofthedrillingmachinewasmadebyasystemofclamps,tomakesurethatvibrationsanddisplacementdoesnotexist,aswecanobserveinFig.3.Thedamagearoundtheholeswasmeasuredwithashopmicroscope,MitutoyoTM500,with30_magnificationand1lmresolution.2.2.Planofexperiments(Taguchi’stechniques)Taguchi_stechniqueshavebeenusedwidelyinengineeringanalysis.Thesetechniquesconsistofaplanofexperimentswiththeobjectiveofacquiringdatainacontrolledway,executingtheseexperiments,inordertoobtaininformationaboutthebehaviorofagivenprocess.Thetreatmentoftheexperimentalresultsisbasedontheanalysisaverageandtheanalysisofvariance(ANOVA)[10–13].FortheelaborationofexperimentsplanweusedthemethodofTaguchifortwofactorsatthreelevels.Bylevelswemeanthevaluestakenbythefactors.Table1indicatesthefactorstobestudiedandtheassignmentofthecorrespondinglevels.ThearraychosenwastheL9(24),whichhasninerowscorrespondingtothenumberoftests(eightdegreesoffreedom)withtwocolumnsatthreelevels,asshowninTable2.Thefactorsandtheinteractionsareassignedtothecolumns.Theplanofexperimentsismadeofninetests(arrayrows)inwhichthefirstcolumnwasassignedtothecuttingvelocityeVTandthesecondcolumntothefeedrateefTandtheremainingwereassignedtotheinteractions.TheresponsetobestudiedisthedelaminationfactoreFdTinCFRPlaminate.3.Resultsanddiscussion江苏大学毕业设计33.1.InfluenceofthecuttingparametersinthedelaminationfactorThedamagearoundtheholeswasmeasuredusingashopmicroscopeMitutoyoTM-500,followingtheschemapresentedintheFig.4.AftermeasuringthemaximumdiametereDmaxTinthedamagezone,i.e.aroundeachhole,wecarriedouttodeterminedthevalueofthedelaminationfactoreFdT.ThisfactorisdeterminedbytheratiothemaximumdiametereDmaxTofthedamagezonetotheholediametereDT.ThevalueofdelaminationfactoreFdTcanbeobtainedbythefollowingequation:Fd¼DmaxDe1Tbeing,DmaxthemaximumdiameterofthedamageholeinlmandDthediameteroftheholeinlm.Table3showstheresultsofthedelaminationfactoreFdT,forthethreesetsofdrillingtests,obtainedbytheEq.(1)infunctionofthecuttingparameters.IntheFigs.5and6wecanobservetheevolutionofthedelaminationfactoreFdTwiththefeedforthedifferentcuttingspeedvalues.InFig.5wecanevidencethattheFdincreaseswiththefeedrate,andwiththecuttingspeed.Accordingtothegraph,wecanobservethatthecarbidedrillpresentsabetterperformancethantheHSSdrill,i.e.underthesamecuttingconditions(cuttingspeedandfeedrate),theHSSdrillcausesalwaysabiggerdelaminationfactor,witchmeanshigherdamageinthecompositelaminate.WealsocanobservethatinFig.6,theFdincreaseswiththefeedrate,andwiththecuttingspeed.Wecanevidencethatthehelicalflute(K10)drillpresentsabetterperformancethanthefour-flute(K10)drill,i.e.underthesamecuttingconditions(cuttingspeedandfeedrate).Thefour-flutedrillcausesalwaysabiggerdelaminationfactor,exceptinthetestwhichhavethehigherfeedrateandthelowercuttingvelocity.Geometricaldifferencesbetweenthetwotypesofdrillmaybethereasonforthisfact.Withanopticalmicroscope(OM)waspossibletoobservethedamagearoundtheholes,andnoticetheinfluenceofthecuttingvelocityeVThaveonthedelaminationfactoreFdT,aswecanseeonFig.7.InFig.7,wecanevidencethat,foraconstantafeedrate,anincreaseofthecuttingvelocityincreasesthedelaminationfactoreFdTaswell.AnanalysisofvarianceofthedatawiththedelaminationfactoreFdTinCFRPlaminate,withtheobjectiveofanalyzingtheinfluenceofthecuttingvelocityeVT,offeedrateefTonthetotalvarianceoftheresults.Thestatisticaltreatmentofthedatawasmadeintwophases.Thefirstphasewasconcernedwiththeanalysisofvarianceandtheeffectofthefactorsandoftheinteractions.Thesecondphaseallowedustoobtainthecorrelationbetweentheparameters(Vandf).Tables4–6showtheresultsoftheanalysisofvariancewiththedelaminationfactoreFdTinCFRPlaminate.FromtheanalysisofTable4,wecanobservethatthecuttingvelocityeP72:5%Tandthefeed

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