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外文翻译碳纤维增强砖钻削分层的研究.doc

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外文翻译碳纤维增强砖钻削分层的研究.doc

附录A外文翻译-原文部分StudyofdelaminationindrillingcarbonfiberreinforcedplasticsCFRPusingdesignexperimentsJ.P.Davim,PedroReisDepartmentofMechanicalEngineering,UniversityofAveiroCampusSantiago,3810193Aveiro,PortugalAbstractInthispaperispresentedanewcomprehensiveapproachtoselectcuttingparametersfordamagefreedrillingincarbonfiberreinforcedepoxycompositematerial.TheapproachisbasedonacombinationofTaguchi_stechniquesandontheanalysisofvarianceANOVA.Aplanofexperiments,basedonthetechniquesofTaguchi,wasperformeddrillingwithcuttingparametersprefixedinanautoclavecarbonfiberreinforcedplasticCFRPlaminate.TheANOVAisemployedtoinvestigatethecuttingcharacteristicsofCFRP_susinghighspeedsteelHSSandCementedCarbideK10drills.TheobjectivewastoestablishacorrelationbetweencuttingvelocityandfeedratewiththedelaminationinaCFRPlaminate.Thecorrelationwasobtainedbymultiplelinearregression.Finally,confirmationtestswereperformedtomakeacomparisonbetweentheresultsforeseenfromthementionedcorrelation._2002ElsevierScienceLtd.Allrightsreserved.KeywordsDrillingCarbonfiberreinforcedplasticsDelaminationfactorTaguchi_stechniquesAnalysisofvariance.1.IntroductionOwingtothegrowinguseofcompositematerials,specificallythefiberreinforcedplasticsFRPoutsidethedefenceindustryandtheaerospaceindustry,theunitcostreplacestheperformanceatanycostasthemainconcernforproduction.So,theproductiontechnologies,especiallythemachiningofcomposites,areassumingamoreandmoresignificantroleastheyconditiontheeconomicviabilityoftheproduct.Machiningcompositematerialsisarathercomplextaskowingtoitsheterogeneity,heatsensitivity,andtothefactthatreinforcementsareextremelyabrasive.Conventionalmachiningmethodsshouldbeadaptedinsuchawaythattheydiminishthermalandmechanicaldamage.Drillingisafrequentlypracticedmachiningprocessinindustryowingtotheneedforcomponentassemblyinmechanicalpiecesandstructures.Thedrillingoflaminatecompositematerialsissignificantlyaffectedbythetendencyofthesematerialstodelaminateandthefiberstobondfromthematrixundertheactionofmachiningforcesthrustforceandtorque.Manyauthors1–3,whenreportingaboutthedrillingoflaminatedcompositematerialsbyconventionaltools,haveshownthatthequalityofthecutsurfacesisstronglydependentonthedrillingparameters,toolgeometryandtoolmaterial.Aninappropriatechoiceoftheseparameterscanleadtounacceptablematerialdegradation,suchasfiberpullout,matrixcratering,thermal江苏大学毕业设计1damageanddelamination.Amongthedefectscausedbydrilling,delaminationappearstobethemostcritical.Laminatedfiberreinforcedply_sundermachiningforcesaresubjecttotheriskofinterlaminarcrackpropagation,calleddelamination.Koenigetal.,studiedin1985themachiningoffiberreinforcedplasticsandconcludedthatahighfeedrateofdrillingwillcauseacrackaroundtheexitedgeofthehole4.Millerpresentedin1987adatabaseonoptimumcuttingparametersfordrillingholeswithminimumlocalmachiningdamage5.HochengandPuw1,in1992presentedastudyofthechipformationandassessesthemachinabilityoftwocompositematerialsThermosetbasedandThermoplasticsbasedandconcludedthatfromcuttingchipstheformerpresentsalargeamountofdeformationinchipformation,whilethelattertendstofracture.Healsonoticedthatcarbon/ABSissuperiortocarbon/epoxyforsurfacequalityandbothholeedges.ChambersandBishop6in1995investigatedtheeffectofthecuttingparametersondrillingcarbon/epoxyandcarbon/peekandconcludedthatthedrillingofcarboncompositesisdependentuponthecharacteristicsofthematrixandthehelicalPCDdrillgeometrygavethebestoverallperformance.Inadditiontotheproblemsoftoolwear,itisverydifficulttoachievethequalityofsurfaceneededfortheaccurateassemblyofcomponentsinmechanicalstructures.Linetal.7in1996,carriedoutastudyondrillingofcarbonfiberreinforcedcompositeathighspeedandconcludedthatanincreaseofthecuttingvelocityleadsaincreasingofthedrillwear.Inthiswaythefactofincreasingthewearofdrillcausesarisingofthrustforce.WenChouChen3in1997studiedthevariationsofcuttingforceswithorwithoutonsetdelaminationduringthedrillingoperationsandconcludedthatthedelaminationfreedrillingprocessesmaybeobtainedbytheproperselectionsoftoolgeometryanddrillingparameters.Piquetetal.8in2000carriedoutastudyofdrillingthincarbon/epoxylaminateswithtwotypesofdrills,ahelicaldrillandadrillofspecialgeometry,andconcludedthatbothdrillsleadsadamageattheentranceinthewallandtheexitofthehole,withtheexceptionofspecialgeometrydrillwhichispossibleasignificantreductioninthefinaldamage.Enemuohetal.9in2001,realizethatwiththeapplicationofthetechniqueofTaguchiandothermethods,werepossibletoachievethecuttingparametersthatallowedtheabsenceofdamageinthedrillingoffiberreinforcedplastics.Alltheaboveworkscontributestothepracticeofcuttingcompositematerials,buttheydonotshowthebasicmechanismsofcutandthecharacterizationofthemachinability.2.Experimentalprocedure2.1.Meansandmaterials许静波干燥机(组)设计2Inordertoachievetheobjectiveofthisexperimentalwork,mainlytheestablishingofcorrelationsbetweenthecuttingconditionswiththedelamination,machiningissueswereeffectuatedwithdifferentcuttingconditions,andwereusedcarbonfiberreinforcedplasticsCFRP_sEpoxymatrixreinforcedwith55ofcarbonfiberfortests.Thiscompositematerialwasproducedbyautoclavewithafiberorientationof0/90degrees,aswecanobserveonFig.1.Theexperimentshadbeencarriedoutinanautoclavelaminatemadeupof16layersoffiberswith4mmofthickness,usingthreedifferenttypesof5mmdiameterdrillspresentedintheFig.2.AhelicalflutehighspeedsteelHSSdrillR415.50500508C0,afourflutecementedcarbideK10drillR950.01H10FandfinallyahelicalfluteK10carbidedrillR415.5050030AC0,accordingtoISO1832.Adrillingmachinewith2,2kWspindlepowerandamaximumspindlespeedof2500rpmwasusedtoperformtheexperiments.Theuseddrillshavean118_pointangle.Thesqueezeofthelaminate,inthepressofjawofthedrillingmachinewasmadebyasystemofclamps,tomakesurethatvibrationsanddisplacementdoesnotexist,aswecanobserveinFig.3.Thedamagearoundtheholeswasmeasuredwithashopmicroscope,MitutoyoTM500,with30_magnificationand1lmresolution.2.2.PlanofexperimentsTaguchistechniquesTaguchi_stechniqueshavebeenusedwidelyinengineeringanalysis.Thesetechniquesconsistofaplanofexperimentswiththeobjectiveofacquiringdatainacontrolledway,executingtheseexperiments,inordertoobtaininformationaboutthebehaviorofagivenprocess.ThetreatmentoftheexperimentalresultsisbasedontheanalysisaverageandtheanalysisofvarianceANOVA10–13.FortheelaborationofexperimentsplanweusedthemethodofTaguchifortwofactorsatthreelevels.Bylevelswemeanthevaluestakenbythefactors.Table1indicatesthefactorstobestudiedandtheassignmentofthecorrespondinglevels.ThearraychosenwastheL924,whichhasninerowscorrespondingtothenumberoftestseightdegreesoffreedomwithtwocolumnsatthreelevels,asshowninTable2.Thefactorsandtheinteractionsareassignedtothecolumns.TheplanofexperimentsismadeofninetestsarrayrowsinwhichthefirstcolumnwasassignedtothecuttingvelocityeVTandthesecondcolumntothefeedrateefTandtheremainingwereassignedtotheinteractions.TheresponsetobestudiedisthedelaminationfactoreFdTinCFRPlaminate.3.Resultsanddiscussion江苏大学毕业设计33.1.InfluenceofthecuttingparametersinthedelaminationfactorThedamagearoundtheholeswasmeasuredusingashopmicroscopeMitutoyoTM500,followingtheschemapresentedintheFig.4.AftermeasuringthemaximumdiametereDmaxTinthedamagezone,i.e.aroundeachhole,wecarriedouttodeterminedthevalueofthedelaminationfactoreFdT.ThisfactorisdeterminedbytheratiothemaximumdiametereDmaxTofthedamagezonetotheholediametereDT.ThevalueofdelaminationfactoreFdTcanbeobtainedbythefollowingequationFd¼DmaxDe1Tbeing,DmaxthemaximumdiameterofthedamageholeinlmandDthediameteroftheholeinlm.Table3showstheresultsofthedelaminationfactoreFdT,forthethreesetsofdrillingtests,obtainedbytheEq.1infunctionofthecuttingparameters.IntheFigs.5and6wecanobservetheevolutionofthedelaminationfactoreFdTwiththefeedforthedifferentcuttingspeedvalues.InFig.5wecanevidencethattheFdincreaseswiththefeedrate,andwiththecuttingspeed.Accordingtothegraph,wecanobservethatthecarbidedrillpresentsabetterperformancethantheHSSdrill,i.e.underthesamecuttingconditionscuttingspeedandfeedrate,theHSSdrillcausesalwaysabiggerdelaminationfactor,witchmeanshigherdamageinthecompositelaminate.WealsocanobservethatinFig.6,theFdincreaseswiththefeedrate,andwiththecuttingspeed.WecanevidencethatthehelicalfluteK10drillpresentsabetterperformancethanthefourfluteK10drill,i.e.underthesamecuttingconditionscuttingspeedandfeedrate.Thefourflutedrillcausesalwaysabiggerdelaminationfactor,exceptinthetestwhichhavethehigherfeedrateandthelowercuttingvelocity.Geometricaldifferencesbetweenthetwotypesofdrillmaybethereasonforthisfact.WithanopticalmicroscopeOMwaspossibletoobservethedamagearoundtheholes,andnoticetheinfluenceofthecuttingvelocityeVThaveonthedelaminationfactoreFdT,aswecanseeonFig.7.InFig.7,wecanevidencethat,foraconstantafeedrate,anincreaseofthecuttingvelocityincreasesthedelaminationfactoreFdTaswell.AnanalysisofvarianceofthedatawiththedelaminationfactoreFdTinCFRPlaminate,withtheobjectiveofanalyzingtheinfluenceofthecuttingvelocityeVT,offeedrateefTonthetotalvarianceoftheresults.Thestatisticaltreatmentofthedatawasmadeintwophases.Thefirstphasewasconcernedwiththeanalysisofvarianceandtheeffectofthefactorsandoftheinteractions.ThesecondphaseallowedustoobtainthecorrelationbetweentheparametersVandf.Tables4–6showtheresultsoftheanalysisofvariancewiththedelaminationfactoreFdTinCFRPlaminate.FromtheanalysisofTable4,wecanobservethatthecuttingvelocityeP725Tandthefeed

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