CompositesA Vision for the Future文档格式.docx
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Whilecompositeshavealreadyproventheirworthasweight-savingmaterials,thecurrentchallengeistomakethemcosteffective.Theeffortstoproduceeconomicallyattractivecompositecomponentshaveresultedinseveralinnovativemanufacturingtechniquescurrentlybeingusedinthecompositesindustry.
Itisobvious,especiallyforcomposites,thattheimprovementinmanufacturingtechnologyaloneisnotenoughtoovercomethecosthurdle.Itisessentialthattherebeanintegratedeffortindesign,material,process,tooling,qualityassurance,manufacturing,andevenprogrammemanagementforcompositestobecomecompetitivewithmetals.
Thecompositesindustryhasbeguntorecognizethatthecommercialapplicationsofcompositespromisetooffermuchlargerbusinessopportunitiesthantheaerospacesectorduetothesheersizeoftransportationindustry.Thustheshiftofcompositeapplicationsfromaircrafttoothercommercialuseshasbecomeprominentinrecentyears.
Increasinglyenabledbytheintroductionofnewerpolymerresinmatrixmaterialsandhighperformancereinforcementfibresofglass,carbonandaramid,thepenetrationoftheseadvancedmaterialshaswitnessedasteadyexpansioninusesandvolume.Theincreasedvolumehasresultedinanexpectedreductionincosts.
HighperformanceFRPcannowbefoundinsuchdiverseapplicationsascompositearmouringdesignedtoresistexplosiveimpacts,fuelcylindersfornaturalgasvehicles,windmillblades,industrialdriveshafts,supportbeamsofhighwaybridgesandevenpapermakingrollers.
Forcertainapplications,theuseofcompositesratherthanmetalshasinfactresultedinsavingsofbothcostandweight.Someexamplesarecascadesforengines,curvedfairingandfillets,replacementsforweldedmetallicparts,cylinders,tubes,ducts,bladecontainmentbandsetc.
Further,theneedofcompositeforlighterconstructionmaterialsandmoreseismicresistantstructureshasplacedhighemphasisontheuseofnewandadvancedmaterialsthatnotonlydecreasesdeadweightbutalsoabsorbstheshock&
vibrationthroughtailoredmicrostructures.Compositesarenowextensivelybeingusedforrehabilitation/strengtheningofpre-existingstructuresthathavetoberetrofittedtomakethemseismicresistant,ortorepairdamagecausedbyseismicactivity.
Anexaminationofthediversityofsomeofthesenewerapplicationsandthesocio-commercialconsiderationsthatunderpintheirintroductiongivesaninstructiveinsightintothefutureofhighperformanceFRP.
Unlikeconventionalmaterials(e.g.,steel),thepropertiesofthecompositematerialcanbedesignedconsideringthestructuralaspects.Thedesignofastructuralcomponentusingcompositesinvolvesbothmaterialandstructuraldesign.Compositeproperties(e.g.stiffness,thermalexpansionetc.)canbevariedcontinuouslyoverabroadrangeofvaluesunderthecontrolofthedesigner.Carefulselectionofreinforcementtypeenablesfinishedproductcharacteristicstobetailoredtoalmostanyspecificengineeringrequirement.
Whilsttheuseofcompositeswillbeaclearchoiceinmanyinstances,materialselectioninotherswilldependonfactorssuchasworkinglifetimerequirements,numberofitemstobeproduced(runlength),complexityofproductshape,possiblesavingsinassemblycostsandontheexperience&
skillsofthedesignerintappingtheoptimumpotentialofcomposites.Insomeinstances,bestresultsmaybeachievedthroughtheuseofcompositesinconjunctionwithtraditionalmaterials.
WhyComposites?
Compositesareabletomeetdiversedesignrequirementswithsignificantweightsavingsaswellashighstrength-to-weightratioascomparedtoconventionalmaterials.Someadvantagesofcompositematerialsoverconventionalonearementionedbelow:
∙Tensilestrengthofcompositesisfourtosixtimesgreaterthanthatofsteeloraluminium.
∙Improvedtorsionalstiffnessandimpactproperties
∙Higherfatigueendurancelimit(upto60%oftheultimatetensilestrength).
∙30-45%lighterthanaluminiumstructuresdesignedtothesamefunctionalrequirements
∙Lowerembeddedenergycomparedtootherstructuralmaterialslikesteel,aluminiumetc.
∙Compositesarelessnoisywhileinoperationandprovidelowervibrationtransmissionthanmetals
∙Compositesaremoreversatilethanmetalsandcanbetailoredtomeetperformanceneedsandcomplexdesignrequirements
∙Longlifeoffersexcellentfatigue,impact,environmentalresistanceandreducedmaintenance
∙Compositesenjoyreducedlifecyclecostcomparedtometals
∙Compositesexhibitexcellentcorrosionresistanceandfireretardancy
∙Improvedappearancewithsmoothsurfacesandreadilyincorporableintegraldecorativemelamineareothercharacteristicsofcomposites
∙Compositepartscaneliminatejoints/fasteners,providingpartsimplificationandintegrateddesigncomparedtoconventionalmetallicparts
TheFutureTrends
Armedwithawidegamutofadvantages,compositeshaveakeyroletoplayinthegrowingmarketinIndia.Compositeshavemadeanentryintodiverseend-usesegmentsandthedevelopmentaleffortsforfindingnewercompositesforexisting&
novelapplicationsisanareaoftoppriority.
TransportationSector
Automobiles
Despitethepotentialbenefitsoflighterweightanddurabilityresultingfromcorrosionresistance,advancedcompositesarenotrecognizedasamaterialofchoiceintheneartermforautomotiveapplications.Significantchangesonabroadspectrumwouldberequiredtomakeadvancedcompositesattractiveforwidespreadcommercialuseincarsandtrucks.Theprincipalbarrieristhehighcostoftheraw&
fabricatedmaterialswhencomparedtoexistingoptions.
Howeverthereareopportunitiesforadvancedcompositesinspecificcomponentsinthecommercialautomotivesector.Inspecialtyvehiclesofseveraltypes,producedinsmallnumbersadvancedcompositematerialshaveanopportunitytodemonstratetheirperformancebenefits,apartfromtherequirementsofthecompetitivemarketplace.
ThecompositeindustryworldwideisinvestinginprocessimprovementsforthemouldingofpolymercompositesusingformsofconventionalE-glassinmid-levelperformanceresins,boththermoplastic&
thermoset.Automobilessegmentofcompositesaccountsforabout50%ofthethermoplasticand24%ofthethermosetcompositemarketintheworld.
Glass-reinforcedthermoplasticpolymerisapromisingmaterialforweightreductionbecauseoftherelativelylowcostofthefibre,itsfastcycletimeanditsabilitytofacilitatepartsintegration.Carbonfibrereinforcedpolymerisanothercandidatebutwillrequirebreakthroughsincostandmanufacturingtechniquestobecosteffectiveforhighvolumeproduction.
Pressureforreductionsinenergyuseandloweremissionslevelsmakesadvancedcompositesafavourableoptionfortheautomotivesector.Thecompositesusageinthissectorisestimatedaround3500TPAby2005AD.Thelikelyfuturebusinessopportunitiesinautomotivesectorarementionedbelow:
∙PultrudedDriveshafts
∙RTMPanel
∙FiberGlass/EpoxySpringsforHeavyTrucksandTrailers
∙RockerArmCovers,SuspensionArms,WheelsandEngineShrouds
∙Filament-WoundFuelTanks
∙ElectricalVehicleBodyComponentsandAssemblyUnits
∙ValveGuides
∙AutomotiveRacingBrakes&
TrainBrakes
∙ClutchPlates
ThoughnotmuchprogresshasbeenmadeinIndiatowardsproductdevelopmentefforts,thisareameritsattentionandholdsalotofpromise.TheprospectsofexportofcompositescurrentlyarelowbecauseIndiadoesnotenjoyanycomparativeadvantageeitherinrawmaterialsorinprocessingcosts.
Theotherareawhichholdspromiseforthecomingdecadeistheuseofmetalmatrixcompositesforcertainautocomponents.Themainadvantageofsuchcompositematerialsystemsisthattheirphysical,mechanicalandthermalpropertiesaretailorableandcandrasticallysurpassthoseofreinforcedmetals.
MMCcanbeextruded,forged,investmentcast,rolled,machined,andheattreated.TransportationapplicationsrepresentoneofthelargestdemandsegmentsforMMCs,andincludeturbineandcombustionenginecomponents,discbrakesandbrakeparts,anddriveshaftcomponents.
Becauseoftheiruniqueproperties,metalmatrixcompositesarealsogaininginterestinahostofhighperformanceapplicationsacrossanumberofindustries.DemandforMMCsisgrowinginthetransportation,electronics,telecommunicationsandpollutioncontrolsectors.ItisexpectedthatMMCsmayexperienceadouble-digitincreaseacrosstheseindustrialmarketsthrough2003.
Marine
Withcompositesexhibitingexcellentresistancetothemarineenvironment,theirapplicationshavemadegoodinroadsinthemarinesectorworldwide.Complexconfigurations&
theadvantagesofseamlesshullswerethemaindrivingfactorsinthedevelopmentofFRPboats.
Racingpower-boatsemployadvanced&
hybridcompositesforahigherperformancecraftanddriversafety.Majorstructuralelementsviz.deckhouses,hatchcovers,kingsposts&
bowmodulesappearstobeverywellsuitedforFRPconstruction.
InIndia,compositeapplicationsinmarinesegmenthasmadesomebeginninginthelastdecadeinhighspeedboats,navalvessel