Composites in commercial aircraft engines V3 Revised...

COMPOSITES IN COMMERCIAL AIRCRAFT ENGINES FACT SHEET THE USE OF COMPOSITES IN COMMERCIAL AIRCRAFT ENGINES

COMPOSITESINCOMMERCIALAIRCRAFTENGINESFACTSHEET

1

IntroductionIn2012,duringoneoftherecordjetfuelpricepeaks,fuelaccountedfor34%ofanairline’sdirectoperatingcosts,makingitthedominantcost.Asaresultofthe fuelpricedecreaseover the last twoyears, fuelaccounted for just21%ofdirectoperatingcosts in2016.1However, fuel is still amajor costdriver forairlines,andthebehaviourofitspricedevelopmentisrelativelyunknown.Therefore,aeroenginemanufacturershavecontinuallydevelopedincreasinglyfuel-efficientengines.Thishas resulted ina35%reduction inaverage fuelburnperaircraftseat/kmforsingle-aisle jetssince1980.2Oneof themost importantfactors leading to more fuel-efficient engines is the increased replacement of metals with composite parts in various engine sections. Aeroenginemanufacturersarecurrentlydevelopingdifferent typesofcomposite-basedengines,andalthoughcompositesare relativelynewandunknown, theiruse inenginesectionsiscontinuingtogrow–themarkethasnearlytripledsince2005.2Theuseofcompositeshasmanyadvantages.Compositesarelighter,strongerandhavemoredesignshapefreedomthanmetals.3Usingtheselightweightcompositematerialsthereforeimprovestheefficiencyanddurabilityoftheenginecomponents.4 However, despite this increased efficiency, composites have disadvantages as well. They are susceptible to a variety of hidden damagesdetectableonlybyadvancedmaintenancetechniques,andtheirfailurerateunderhightemperatures(e.g.inhigh-pressureturbines)isrelativelyunknown.Tolook at the impact of composites, this factsheet also focuses on the largest consumers of these engine components: CFM International and GE (GeneralElectric)Aviation.These twoaeroenginemanufacturershave recently createdanew typeofenginewitha largenumberof compositeparts for theAirbusA320NEO(NewEngineOption)andBoeing737MAX.Theonlysectionsinwhichcompositesarenotusedyetarethecombustorandlow-pressureturbine.Thefansectionof theenginecontainsthehighestamountofcompositematerials.Figure1 illustratesthedifferentsectionsofaturbofanengine,whileTable1depictstheapplicationofcompositepartsinthesesections.

Figure 1. Different sections of a turbofan engine (Bremer, M. 2013). Table 1. Typical applications of composites in turbofan engines (Red, C. 2015).


2

CompositesA compositematerial is a combination of two ormore distinctmaterialswitharecognizableinterfacebetweenthem.Oneormoreofthematerials–calledthereinforcingphase–areintheformoffibresembeddedintheother material – called the matrix – as depicted in Figure 2.5 Thiscombinationcreateshighermechanicalandphysicalmaterialpropertiesincomparison to only one of these materials. Composite components areselectedsothattheymaximisetheiroutstandingproperties.6

CFRP (carbon fibre reinforced polymer – carbon fibres embedded in apolymerresinmatrix)andCMC(ceramicmatrixcomponents–carbonfibresembedded in a ceramic matrix) are mainly used for components in aturbofanengine.Thisfactsheetthereforefocusesonthesematerials.

AdvantagesanddisadvantagesofcompositesCarbonandceramicfibresbringsignificantadvantages.Theyareverylight,resultinginlightweightstructures.Theirthermalexpansionisbasicallyzero,sothatCFRPandCMCretaintheir itsbasicformwhenheated7,8.CMCcanresist very high temperatures (1300 Celsius)9, and composite structuressuffer from fewer fatigue issues than metals when designed anddimensioned properly. Finally, CFRP is permeable to X-rays and does notcorrode,whichisahugeissuewithmetals.7,8 Composites also have disadvantages. For instance, they are are fairlyexpensive compared to other fibres. Carbon fibre is also an electricconductor and can cause corrosion in other metals. When the materialbreaks, the parts disintegrate – which can lead to unpredictableresults.Finally,themanufacturingprocessforcompositecomponentscanbemorelabour-intensive than formetallic parts.7,8 Figure 3 shows the advantagesanddisadvantagesofCFRPandCMCforuseinaeroenginesasopposedtothetraditionalmetalstructures.

Figure 3. Advantages vs Disadvantages of composites Figure 2. Structure of a composite. (Bavan, D. 2013)


3

TheincreaseduseofcompositesincommercialaircraftenginesTheapplicationofcompositesincommercialaircraftengineswasrelativelylimiteduptotheturnofthecentury.Morethanhalfofthetotalcompositevolume was directly associated with nacelle (the housing that holds theengine to theaircraft)andcowlingcomponents.2However, increased fuelpricesledaeroenginemanufacturerstocreatemorefuel-efficientengines,with weight playing an important role. As composites are lighter thanmetals,enginemanufacturersfocusedoncreatingcompositeengineparts.GE’s GE90 engine entered into service in 1995, and applied many moreadvanced materials and resin transfer moulding (RTM) processing tointroduceanumberofnewcomposite components –mostnotably, largefan bladesmade fromhundreds of plies of intermediate-modulus carbonfibre prepreg.2 Since then, composites have continued to account for anincreasing share turbofans,witha commensurate reduction indryweight(Figure4).

Figure 4. Turbofan Engine Composite Usage vs. Engine Dry Weight (the blue dots represent different engine

types). (Red, C. 2015).

AeroenginemanufacturersMany aeroengine manufacturers have significant in-house compositemanufacturing capacity. GE Aviation, for example, has US facilities inBatesville,MS;Newark,DE;Baltimore,MD;Asheville,NC;andEllisville,MS,as well as joint-venture subsidiaries. Rolls-Royce has purchased a largenumberofsmallfibre-placementmachinesfortheproductionofcompositefanbladesfortheirupcomingengineplatforms.2

CFM InternationalandGEAviationarecurrently the largest consumersofcomposite engine components – together, they represent about 72% oftotalaeroenginecompositedemand.Overthenextseveralyears,however,Rolls-Royce’s Trent and Pratt &Whitney’s PurePower engine families areexpected to account for a considerable portion of the remaining 28%(Figure5).2

Figure 5. Consumers of composite engine components. (Red, C. 2015).

The next section will discuss two engines developed by the largestcomposite-based aeroengine manufacturers: CFM International and GEAviation.

72%

28%

Consumersofcompositeenginecomponents

CFMInternafonal&GEAviafon

Rolls-Royce’sTrentandPrag&Whitney’sPurePowerenginefamilies&Other


4

CFMInternationalLEAP–1A&GeneralElectricPassportThe LEAP – 1A engine,manufactured by CFM international, entered intoservice in August of 2016.10 One of the differences of the LEAP enginecomparedtoitspredecessor(theCFM56)isanincreaseduseofcompositematerials. The LEAP therefore delivers a 15% improvement in fuelconsumptioncomparedtotheCFM56,whilemaintainingthesamelevelofdispatchreliabilityandlife-cyclemaintenancecosts.4The LEAP engine’s fan blades are manufactured from a 3-D woven RTMcarbonfibrecomposite,whichisanindustryfirstforCFM.Thistechnologyresults infanbladesthatarenotonly lightweightbutalsosodurablethateach individual blade is strong enough to support the weight of a wide-body airplane such as theAirbus A350 or the Boeing 787.4 The LEAPengine’s basic architecture is based on the GEnx (General Electric next-generation)engine,whichalsohascarbonfibrefanbladesandacompositefancase(usedbythenewBoeing747-8and787aircraft).TheLEAPenginealso uses CMCmaterials in its high-pressure turbine shrouds in order toreduceweightandoptimizeairflowcooling.11

TheAirbusA320NEOandtheBoeing737MAXarethefirstairplanestouseLEAP engines. However, the LEAP engine has now attracted more than5000ordersanditisexpectedthatthisamountwillcontinuetogrow.12

TheGeneral Electric Passport engine is currently under development andusescompositepartssimilartothoseusedinLEAPengines.Theenginewillbeusedfor largebusinessandregional jets.13 Ithasacompositefancase,andCMCmaterialswillbeusedintheexhaust,centre-bodyandcorecowls.

Theseadvantageswillenhancedurabilityandlowerfuelconsumption.14

ConclusionandresearchonthefutureofcompositesTheadvantagesofusingcompositematerialsinaeroenginesareclear:theyreduceweight,whichenablesairplanestoflyfurtheronlessfuel,andtheyhaveanincreasedabilitytoresistfatigueandcorrosion.Inthefuture,theuseofcompositescouldincludetheabilitytoprotecttheengineagainstlightning.Researchersarecurrentlydevelopingacompositecoatingthatcouldaddthispositivefeaturetoaircraftengines.15Ahigherenginebypassratio(BPR)resultsinbetterfuelefficiency.CFRPhasincreasinglybeenusedinaeroengines,doublingBPRsince1970.16BecauseofthematerialpropertiesofCFRP,futureturbofanscanhaveahighersizeof the air-delivering turbofan. So the use of composite material inaeroengines will contribute to more efficient engines. CFRPs will also beusedinfancasestopreventdamageelsewhereintheaircraftifafanblade‘shootsoff’duringoperation.16

An exciting new opportunity in compositemanufacturing is the ability touse 3D printing techniques to produce aeroengine parts. Advanced 3Dprintingcancreatetherequiredshapesthatcannotbeproducedanyotherway.Itcanalsoreducethenumberofpartsusedinanengineandeliminatetheneed to screwconnectpieces together. Engine sections that arenowmadeoutofseveralpartscouldbereducedtoone.DevelopmentsincompositeswillincreasetheirshareoftheestimatedUSD3millionmarketinaircraftenginedevelopmentbetweennowand2030.16


5

Glossary• Directoperatingcosts: the totalof flightoperationscosts (flightcrew

salariesandexpenses,aircraftfuelandoils,aircraftinsurances,aircraftrentals,flightcrewtrainingandotherflightexpenses).

• Turbofanengine:atypeofby-passengineinwhichalargefan,driven

by a turbine andhoused in a short duct, forces air rearwards aroundtheexhaustgasesinordertoincreasethepropulsivethrust.

• Spinnercone:theconicalpartofanaeroengineset infrontofthefan

bladesmountingpointtoimproveaerodynamics.• Fanblade:theflatsurfacethatrotatesandpushesagainstairorwater.• Bypass duct: an annular passage that allows some of a turbofan's

airflowtobypasstheenginecore.• Stator vane: a stationary airfoil that reduces the rotational air

movementcomingfromthespinningfanblades.• Guidevane:afixedairfoilthatdirectsair,gasorwaterintothemoving

bladesofaturbineorinto/aroundbendsinductswithaminimumlossofenergy.

• Exhaustnozzle:theterminalportionofthetailpipeofajetengine.• Fibre:athinthreadofnaturalorartificialmaterialthatcanbeusedto

makecloth,paper,etc.• Matrix:materialinwhichsomethingisenclosedorembedded.• Resin Transfer Molding (RTM): an increasingly common form of

moulding,usingliquidcomposites.

• Prepreg: thecommontermfora reinforcing fabric thathasbeenpre-impregnatedwitharesinsystem.

• Enginebypassratio(BPR):theratiooftheamountofairthatbypasses

the combustion chambers of an aircraft gas turbine to that passingthroughthem.

References1.Statista.(2016).Fuelcostsofairlinesworldwidefrom2011to2016,aspercentageofexpenditure.Retrievedfromhttps://www.statista.com/statistics/591285/aviation-industry-fuel-cost/2.Red,C.(2015,June01).Compositesincommercialaircraftengines,2014-2023.Retrievedfromhttp://www.compositesworld.com/articles/composites-in-commercial-aircraft-engines-2014-20233.Niu,M.C.Y.(1992).CompositeAirframeStructures-PracticalDesignInformationandData(3rdEdition).ADAdaso/AdastraEngineeringLLC.4.CFMinternational.(2015).TheLEAPengine.Retrievedfromhttps://www.cfmaeroengines.com/engines/leap/5.Messler,R.W.,Messler,R.W.Jr.(2011).TheEssenceofMaterialsforEngineer.London:Jones&BartlettLearningInternational.6.VerbundwerkstoffeundWerkstoffverbunde,definitionundEinsatz.(2016,January10).RetrievedOctober6,2016,fromhttp://www.wotech-technicallmedia.de7.Fiberreinforcedcomposites-.(2016,March7).RetrievedOctober6,2016,fromInDepth,http://altairenlighten.com/in-depth/fiber-reinforced-composites/


6

8.IITR.(2013).Lecture6.1:Ceramicmatrixcomposites.Retrievedfromhttp://nptel.ac.in/courses/112107085/module6/lecture1/lecture1.pdf9.Mandigo,G.,&Freitag,D.(2015,February28).APrimeronceramicmatrixcomposites.RetrievedOctober6,2016,fromBusiness,http://compositesmanufacturingmagazine.com/2015/02/a-primer-on-ceramic-matrix-composites/10.Trimble,S.(2016,August02).PegasusstartsflyingLeap-1A-poweredA320neo.Retrievedfromhttps://www.flightglobal.com/news/articles/pegasus-starts-flying-leap-1a-powered-a320neo-428117/11.Norris,Guy,Hotblades,AviationWeek&SpaceTechnology,April27-May10,2015,p.5512.Norris,Guy,Pressuretesting,AviationWeekandSpaceTechnology,October28,2013,p.4313.GEAviation.(2015).GEPassport.Retrievedfromhttp://www.geaviation.com/bga/engines/passport/

14.GEAviation.(2014,December30).GE’sPassportengineforBombardierGlobal7000/8000beginsflight-testingonhistoric747.Retrievedfromhttp://www.geaviation.com/press/business_general/bus_20141230b.html15.TheOutlookforThermoplasticsinAerospaceComposites,2014-2023.Retrievedfromhttp://www.compositesworld.com/articles/composites-in-commercial-aircraft-engines-2014-202316.AeroengineComposites,Part2:CFRPsexpand.Retrievedfromhttp://www.compositesworld.com/articles/aeroengine-composites-part-2-cfrps-expand

Imagereferences(toptobottom,lefttoright)

Cover:https://www.flickr.com/search/?text=%20a320%20neoFigure1.Bremer,M.,VanDijk,R.,&VanAalst,R.(2013).EnginePerformance(3rded.).Amsterdam:AmsterdamUniversityofAppliedSciences.Table1.Red,C.(2015,June01).Compositesincommercialaircraftengines,2014-2023.Retrievedfromhttp://www.compositesworld.com/articles/composites-in-commercial-aircraft-engines-2014-2023Figure2.Bavan,D.,&CKumar,G.(2013).FiniteElementAnalysisofaNaturalFiber(Maize)CompositeBeam.Retrievedfromhttps://www.hindawi.com/journals/je/2013/450381/Figure3.CreatedbyLukasFigure4.Red,C.(2015,June01).Compositesincommercialaircraftengines,2014-2023.Retrievedfromhttp://www.compositesworld.com/articles/composites-in-commercial-aircraft-engines-2014-2023Figure5.Red,C.(2015,June01).Compositesincommercialaircraftengines,2014-2023.Retrievedfromhttp://www.compositesworld.com/articles/composites-in-commercial-aircraft-engines-2014-2023


7

DutchSummaryDezefactsheetgeeftinzichtindewereldvandecomposieten.Composietenwordengebruiktindeluchtvaartomgewichttebesparentenopzichtevanoriginelematerialenzoalsmetalen.Ditkomtomdatvliegtransportergduuris,watvoornamelijkdeoorzaakisvandehogebrandstofprijzen.Mededoorgewichtsreductie kunnenvliegtuigendiemeer composietbevatten verdervliegen. Daarnaast zijn composieten minder tot niet vatbaar voorvermoeiing en corosie. Composiet materiaal bestaat uit verschillende“lagen”. Deze lagen bestaan uit verschillende materialen die, wanneersamengevoegd een nieuw composiet bewerkstelligen. Hierbij is het doelomdepositievekenmerkenenkwaliteitenvanbeidematerialen inelkaarnaarboventehalen.Delaatstejarenishetgebruikvancomposietenhardgestegen. Ook in vliegtuigmotoren is deze trend te vinden en wordencomposieten veelvoudig gebruikt. CFM International en GE Aviation (dezogeheten LEAP Engine) zijn momenteel marktleider wat betreft hetgebruikvancomposietenindevliegtuigmotoren.Tochisdezeapplicatiebijvrijwelelkefabrikantterugtevindendooreerdergenoemdevoordelen.Eenvan de interessantste ontwikkeling om te volgen is het 3D printen vancomposiet, wat voor velen voordelen zorgt in het productieproces vanvliegtuigmotoren.

ThisisaLuchtvaartfeiten.nl/AviationFacts.eupublication.Authors:FurkanBahar,LukasLammer&BobLaarmanEditorialstaff:R.J.deBoerPhD,MSc;G.Boosten,MSc;&G.J.S.Vlaming,MSc.Copyingtextsisallowed.Pleasecite:‘AviationFacts.eu(2016),Compositesincommercialaircraftengines,www.AviationFacts.eu’AviationFacts.euisaninitiativebytheAviationAcademyattheAmsterdamUniversityofAppliedSciences(AUAS).Studentsandteachersshareknowledgewithpoliticiansandthegeneralpublictoensurethatdiscussionsarebasedonfacts.December2016

Composites in commercial aircraft engines V3 Revised...

Documents

Transcript of Composites in commercial aircraft engines V3 Revised...