Abaris Composites

7/29/2019 Abaris Composites

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Advanced Composite AircraftAdvanced Composite Aircraft

Structures, StructuralStructures, StructuralRepairs, Adhesive Bonding &Repairs, Adhesive Bonding &

Electrical CharacteristicsElectrical Characteristics

Michael J. HokeMichael J. HokeAbaris Training Resources Inc.Abaris Training Resources Inc.

AEA 2008AEA 2008CopyrightCopyright2008 Abaris Training Resources Inc.2008 Abaris Training Resources Inc. 11


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CopyrightCopyright2008 Abaris Training Resources Inc.2008 Abaris Training Resources Inc. 22

Who is Abaris Training??Who is Abaris Training?? We have been training in manufacturing,We have been training in manufacturing,

repair, and bonding of advancedrepair, and bonding of advancedcomposite structures since 1983, with overcomposite structures since 1983, with over13,000 graduates to date.13,000 graduates to date.

Three permanent training facilities:Three permanent training facilities: Reno, NVReno, NV

Griffin, GAGriffin, GA Cwmbran, WalesCwmbran, Wales

We also do numerousWe also do numerous onon--sitesite classesclasses


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Who do we train?Who do we train? 40% military40% military

25% manufacturers (Boeing, Airbus,25% manufacturers (Boeing, Airbus,NorthropNorthrop--Grumman, Lockheed, GeneralGrumman, Lockheed, General

Atomics (UAVAtomics (UAVs), Cessna, etc.)s), Cessna, etc.) 20% airlines and large MRO20% airlines and large MROss

10% Gov: FAA, NTSB, NASA, etc.10% Gov: FAA, NTSB, NASA, etc.

5% non5% non--aerospaceaerospace


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Why Reno?Why Reno? -- LearFanLearFan


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WhatWhats up for today?s up for today? Basics of CompositesBasics of Composites Strings and GlueStrings and Glue

Fibers and Fiber FormsFibers and Fiber Forms the Stringsthe Strings

Matrix SystemsMatrix Systems the Gluethe Glue

Adhesive BondingAdhesive Bonding Damage and InspectionDamage and Inspection



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WhatWhats up for today?s up for today? Structural Repair techniquesStructural Repair techniques

Vacuum BaggingVacuum Bagging

Radome RepairRadome Repair

Lightning Strike ProtectionLightning Strike ProtectionAntenna InstallationsAntenna Installations



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What Are Composites?What Are Composites?

Made up of two main types of materials:Made up of two main types of materials: FibersFibers

Carry majority of the loadCarry majority of the load

MatrixMatrix

Gives the part its shape, protects fibersGives the part its shape, protects fibers


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The Basics: Cloth and GlueThe Basics: Cloth and Glue --

Wet LayupWet Layup


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An alternative: PrepregAn alternative: Prepreg


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Typical Sandwich ConstructionTypical Sandwich Construction


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FibersFibers The fibers give the part most of its strength andThe fibers give the part most of its strength and

distinctive characteristics:distinctive characteristics: Glass or fiberglass (white)Glass or fiberglass (white)

Good strength and stiffness, good impactresistance, heavier

Carbon or Graphite fiber (black)Carbon or Graphite fiber (black) Very high bending stiffness, high tensile and

compressive strength, poor impact resistance, light

KevlarKevlar

fiber (yellow)fiber (yellow) Excellent impact resistance, high tensile strength,poor compressive strength, light weight

The fibers carry most of the load!The fibers carry most of the load!


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Matrix systems (resins)Matrix systems (resins) PolyestersPolyesters

Vinyl EstersVinyl Esters

EpoxiesEpoxies BismaleimidesBismaleimides

Cyanate EstersCyanate Esters

PhenolicsPhenolics

OthersOthers

Each type of fiber and resin has different structuralEach type of fiber and resin has different structuralproperties and temperature tolerance.properties and temperature tolerance.


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FabricFabric : material constructed of: material constructed ofinterlaced yarns, fibers, or filamentsinterlaced yarns, fibers, or filaments


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Many Weave Styles; This isMany Weave Styles; This is

Eight Harness Satin weaveEight Harness Satin weave


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Unidirectional TapeUnidirectional Tape: Non: Non--wovenwovenmaterial in which the filaments are laid inmaterial in which the filaments are laid ina single direction within a resin matrix;a single direction within a resin matrix;

multiple plies used.multiple plies used.


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Military AircraftMilitary Aircraft

BB--2:2:Approximately 85% of the structuralApproximately 85% of the structural

weight is compositeweight is composite

FF--2222

FF--3535


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BoeingBoeing

Bird of PreyBird of Prey


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Commercial AircraftCommercial Aircraft

Boeing 777Boeing 777

Boeing 787Boeing 787

Airbus AAirbus A--380380

AA--380 fuselage380 fuselagecrosscross--sectionsection


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HighHigh--Performance SailplanesPerformance Sailplanes


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DiamondDiamond


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Cessna 300/350/400Cessna 300/350/400


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Cirrus SRCirrus SR--20 and 2220 and 22


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Critical Areas of DamageCritical Areas of Damage


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New Honda Jet HF 118New Honda Jet HF 118

Honda Jet employs anHonda Jet employs an

allall--carbon fibercarbon fiberreinforced epoxyreinforced epoxy

fuselagefuselage


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Unmanned Aerial VehiclesUnmanned Aerial Vehicles

(UAV)(UAV)

NorthropNorthrop--

GrummanGrummanGlobalGlobalHawkHawk

BoeingBoeingUCAVUCAV

Tit IVB b fib b t


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Titan IVB carbon fiber boosters:Titan IVB carbon fiber boosters:

114114 long, 10long, 10 diameterdiameter


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Swedish VisbySwedish Visby--class 240 foot (73m)class 240 foot (73m)

all carbonall carbon--fiber lowfiber low--observable shipobservable ship


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Large Sailing VesselsLarge Sailing Vessels

Mirabella VMirabella V-- 246 feet246 feet --Worlds largest composite yachtWorlds largest composite yacht

Cost: $55 MillionCost: $55 Million

246' long with a246' long with abeam of 48.6'.beam of 48.6'.

Her 30,042 sq. ft. ofHer 30,042 sq. ft. ofsail is carried by asail is carried by a290' high carbon290' high carbonfiber mast built in fivefiber mast built in fivesections.sections.

Even a J boat will lookEven a J boat will looksmall next to Mirabella V.small next to Mirabella V.


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Large Windmill BladesLarge Windmill Blades

Blade SectionBlade Section


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Transport of a LM 38.8 m rotor bladeTransport of a LM 38.8 m rotor blade

Onshore Blade TransportationOnshore Blade Transportation


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So composites may be hereSo composites may be hereto stay; not a passing fad.to stay; not a passing fad.

There are many applications in a wideThere are many applications in a wide

variety of industries, and the list isvariety of industries, and the list isgrowing daily.growing daily.

However, this remains a somewhatHowever, this remains a somewhatimmature technology; weimmature technology; were all stillre all still

learning lessons the hard way aboutlearning lessons the hard way aboutthese materials!these materials!


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Advanced CompositeAdvanced CompositeFibers and Fiber FormsFibers and Fiber Forms

The stringy part ofThe stringy part of

the string and glue!the string and glue!

Many Types of Fibers but forMany Types of Fibers but for


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Many Types of Fibers, but forMany Types of Fibers, but for

advanced composites:advanced composites: GlassGlass

QuartzQuartz Carbon/GraphiteCarbon/Graphite

Aramid (KevlarAramid (Kevlar

)) BoronBoron

UHMW Polyethylene (SpectraUHMW Polyethylene (Spectra

)) CeramicCeramic


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Fiberglass clothFiberglass cloth


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KevlarKevlarAramid fiber yarnAramid fiber yarn


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Carbon Unidirectional TapeCarbon Unidirectional Tape

Prepreg rollPrepreg roll


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Fiberglass (White)Fiberglass (White)

Good strength in both tension and compressionGood strength in both tension and compression

Good energy absorption propertiesGood energy absorption properties Low costLow cost

Easy to work withEasy to work with

Moisture resistantMoisture resistant Electrical insulatorElectrical insulator

HeavyHeavy

Some types can be affected by an alkalineSome types can be affected by an alkalineenvironmentenvironment


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KevlarKevlar aramid fiber (Yellow)aramid fiber (Yellow)

Much lighter than fiberglassMuch lighter than fiberglass

Very good energy absorptionVery good energy absorption Excellent in tension, poor in compressionExcellent in tension, poor in compression

Electrical insulatorElectrical insulator

Moderately expensiveModerately expensive Absorbs some moistureAbsorbs some moisture

Sensitive to UVSensitive to UV

Bonds poorly to polyester resinsBonds poorly to polyester resins


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Carbon (graphite) fiber (Black)Carbon (graphite) fiber (Black)

Excellent in tension and compressionExcellent in tension and compression

Excellent in bending stiffnessExcellent in bending stiffness Partial absorber of microwaves; donPartial absorber of microwaves; dont use in at use in a

radome!radome!

Poor at impact energy absorptionPoor at impact energy absorption -- brittlebrittle

ExpensiveExpensive

Electrically conductive!Electrically conductive!

Can cause galvanic corrosion problems with carbonCan cause galvanic corrosion problems with carbonsteel, cadsteel, cad--plated fasteners, and especiallyplated fasteners, and especiallyaluminum!aluminum!

MaterialMaterial Galvanic ScaleGalvanic Scale

M i 12 ANODIC


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4040

MagnesiumMagnesium 1212 ANODICANODIC

ZincZinc 1111

Aluminum 7075 CladAluminum 7075 Clad 1010Aluminum 2024 CladAluminum 2024 Clad 99

Aluminum 7075Aluminum 7075--T6T6 99

CadmiumCadmium 88

Aluminum 2024Aluminum 2024--T4T4 77

Wrought SteelWrought Steel 66

Cast SteelCast Steel 66

LeadLead 44

TinTin 44

Manganese BronzeManganese Bronze

33

BrassBrass 22

Aluminum BronzeAluminum Bronze 22

CopperCopper 22

NickelNickel 11

InconelInconel 11

Type 303 StainlessType 303 Stainless 00

TitaniumTitanium 00

MonelMonel 00

SilverSilver 00

Carbon FiberCarbon Fiber 00 CATHODICCATHODICCopyrightCopyright2008 Abaris Training Resources Inc.2008 Abaris Training Resources Inc.


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Boron fiberBoron fiber

Excellent in tensile strengthExcellent in tensile strength

Even better in compressive strengthEven better in compressive strength ananunusual property for a fiberunusual property for a fiber

Very high modulusVery high modulus

Tungsten coreTungsten core

BrittleBrittle ExpensiveExpensive

Difficult to cutDifficult to cut

Now used mostly for bonded repairs to crackedNow used mostly for bonded repairs to crackedmetallic structures.metallic structures.


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Polyethylene (SpectraPolyethylene (Spectra) fiber) fiber

UHMW PolyethyleneUHMW Polyethylene

Excellent in tensionExcellent in tension Very resistant to impactsVery resistant to impacts

BulletproofBulletproof vests, helmets, etc.vests, helmets, etc.

Impervious to waterImpervious to water

Difficult to bond to matrix systemsDifficult to bond to matrix systems

Poor at high temperatures (+212Poor at high temperatures (+212F)F) Occasionally seen in radomes or antennaOccasionally seen in radomes or antenna

covers.covers.


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Quartz fibersQuartz fibers

Another form of glassAnother form of glass

Good at high temperaturesGood at high temperatures Good tensile & compressive strengthGood tensile & compressive strength

Microwave transparentMicrowave transparent

ExpensiveExpensive

Sometimes used in radomes, especiallySometimes used in radomes, especiallyon Airbus aircrafton Airbus aircraft

C f


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Ceramic fibersCeramic fibers

Usually used in short forms, with ceramicUsually used in short forms, with ceramic

or metal matrix systemsor metal matrix systems Excellent at really high temperaturesExcellent at really high temperatures

Often used in ballistic armorOften used in ballistic armor Very expensiveVery expensive

Difficult to processDifficult to process

F f R i f t


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Forms of ReinforcementForms of Reinforcement

Filaments/tows/strands/yarns/rovingsFilaments/tows/strands/yarns/rovings

Mats (chopped strand, continuous)Mats (chopped strand, continuous)

Unidirectional tapeUnidirectional tape

Woven rovingWoven roving

Woven textile fabricsWoven textile fabrics Plain weave, satin weaves, twills, etc.Plain weave, satin weaves, twills, etc.

Stitchbonded fabricsStitchbonded fabrics BraidsBraids

Si i /Fi i hSi i /Fi i h


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Sizing/FinishesSizing/Finishes

Used to coat filaments to improve bondingUsed to coat filaments to improve bonding

Many different types, compatible withMany different types, compatible withdifferent resin systemsdifferent resin systems

Some polyesterSome polyester--compatible sizings are notcompatible sizings are not

compatible with epoxies, and vice versacompatible with epoxies, and vice versa Special surface treatments for some fibersSpecial surface treatments for some fibers

(e.g.: ion bombardment for UHMW(e.g.: ion bombardment for UHMWpolyethylene)polyethylene)

Carbon almost alwaysCarbon almost always sizedsized for epoxiesfor epoxies

Fib /R i R tiFib /R i R ti


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Fiber/Resin RatioFiber/Resin Ratio

Too little resin: resin starvedToo little resin: resin starved

Compressive properties strongly degradedCompressive properties strongly degraded Too much resin: resin richToo much resin: resin rich

Heavy, brittle, weakHeavy, brittle, weak

If the right amount of resin is good, more resin isIf the right amount of resin is good, more resin isNOT better!NOT better!

For most woven cloth, about 60% fiber,For most woven cloth, about 60% fiber,40% resin by weight is OK.40% resin by weight is OK.

C tC t


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CostsCosts

Tremendous variation in cost:Tremendous variation in cost:

Fiberglass: $1Fiberglass: $1 -- $6/lb.$6/lb. Kevlar: $8Kevlar: $8 -- $15/lb.$15/lb.

Carbon fiber: $8Carbon fiber: $8 -- $4,000/lb.$4,000/lb.

Boron: $650/lbBoron: $650/lb

T f Gl FibT f Gl Fib


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Types of Glass FibersTypes of Glass Fibers

AA HighHigh--AlkaliAlkali

EE ElectricalElectrical SS StructuralStructural

SS--22 Commercial grade SCommercial grade S--glassglass

DD Dielectric gradeDielectric grade

MM HighHigh--modulus (Boronmodulus (Boron--rich)rich)

T f Gl Fib (C t )T f Gl Fib (C t )


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Types of Glass Fibers (Cont.)Types of Glass Fibers (Cont.)

CC Chemical ResistantChemical Resistant

EE--CRCR Corrosion ResistantCorrosion Resistant RR HighHigh--strength, high modulusstrength, high modulus

LeadLead Radioactivity resistantRadioactivity resistant

LithiumLithium--OxideOxide XX--Ray transparentRay transparent

F b i ll t i lFabric roll terminology


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Fabric roll terminologyFabric roll terminology

Ply OrientationPly Orientation


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Ply OrientationPly Orientation

Warp ClocksWarp Clocks

CCWCCW CWCW

0

90+45

-45

0

90-45

+45

SymmetrySymmetry


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SymmetrySymmetry

BalanceBalance


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BalanceBalance

QuasiQuasi IsotropicIsotropic


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QuasiQuasi--IsotropicIsotropic

Nesting vs StackingNesting vs Stacking


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Stacked Layers

Nested Layers

Nesting vs. StackingNesting vs. Stacking

So to build a part properly:So to build a part properly:


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So to build a part properly:So to build a part properly:

Depending on the weave style, one mightDepending on the weave style, one might

make a quasimake a quasi--isotropic, balanced,isotropic, balanced,symmetrical, nested layup.symmetrical, nested layup.

This is as opposed to the usual repairThis is as opposed to the usual repairtechnique: slap some plies on, and ittechnique: slap some plies on, and itss

Miller time!Miller time!

Practical issues with fibers:Practical issues with fibers:


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Practical issues with fibers:Practical issues with fibers:

DonDont use carbon fiber with polyester ort use carbon fiber with polyester or

vinylester resin systemsvinylester resin systems Make sure fiberglass has the proper sizingMake sure fiberglass has the proper sizing

for the resin system you are usingfor the resin system you are using

Worry about UV attack on KevlarWorry about UV attack on Kevlar it mustit mustbe painted.be painted.

DonDont use Kevlar with polyester resins;t use Kevlar with polyester resins;vinylester is OK; epoxy is best.vinylester is OK; epoxy is best.

Practical issues with fibersPractical issues with fibers


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(continued):(continued):

Be very meticulous about surfaceBe very meticulous about surfacepreparation and cleanliness for adhesivepreparation and cleanliness for adhesivebonding.bonding.

Pay close attention to fiber orientation onPay close attention to fiber orientation onwoven cloth or unidirectional structures.woven cloth or unidirectional structures.


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Matrix SystemsMatrix Systems

The glue that holds the stringsThe glue that holds the stringstogether!together!

Matrix Systems must:Matrix Systems must:


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Matrix Systems must:Matrix Systems must:

Transfer loads from fiber to fiberTransfer loads from fiber to fiber

Keep fibers from bucklingKeep fibers from buckling

Give the component a rigid shapeGive the component a rigid shape

Protect the fibers from the environmentProtect the fibers from the environment Handle temperature extremesHandle temperature extremes

MatrixMatrix requiredrequired to attain theseto attain these


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structural properties:structural properties: CompressionCompression

Fibers can carry compressive loads, but onlyFibers can carry compressive loads, but onlyif they are prevented from buckling!if they are prevented from buckling!

ShearShear

Bending stiffnessBending stiffness

MatrixMatrix dominatesdominates thesethese


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structural properties:structural properties: Interlaminar shear (resistance toInterlaminar shear (resistance to

delamination)delamination) Interlaminar tension (peel)Interlaminar tension (peel)

Service TemperatureService Temperature

Matrix types:Matrix types:


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Matrix types:Matrix types:

Organic (Plastics)Organic (Plastics)

ThermosetsThermosets ThermoplasticsThermoplastics

CarbonCarbon

MetalMetal

CeramicCeramic

Thermoset Matrix SystemsThermoset Matrix Systems


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Thermoset Matrix SystemsThermoset Matrix Systems

CrosslinkingCrosslinking

OneOne--time irreversible chemical reactiontime irreversible chemical reaction

Cannot be reCannot be re--formed or melted after curingformed or melted after curing

Difficult to recycleDifficult to recycle

Thermosets include:Thermosets include:


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Thermosets include:Thermosets include:

PolyestersPolyesters

VinylestersVinylesters EpoxiesEpoxies

PhenolicsPhenolics

Cyanate EstersCyanate Esters

BismaleimidesBismaleimides

Some PolyimidesSome Polyimides PolyurethanesPolyurethanes

Thermoplastic Matrix SystemsThermoplastic Matrix Systems


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Thermoplastic Matrix Systemsp y

LongLong--chain moleculeschain molecules

Undergoes a physical change from a solidUndergoes a physical change from a solidto a liquid when heatedto a liquid when heated

Can be reCan be re--heated and reheated and re--formed, melts atformed, melts athigh temperatures, easier to recycle thanhigh temperatures, easier to recycle thanthermosetsthermosets

Thermoplastics include:Thermoplastics include:


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e op ast cs c udep

PlexiglasPlexiglas

ABS (Acrylonitrile butadiene styrene)ABS (Acrylonitrile butadiene styrene) PolyethylenePolyethylene

PEI (Polyetherimide)PEI (Polyetherimide)

PEEK (Polyetheretherketone)PEEK (Polyetheretherketone)

PPS (Polyphenylene sulfide)PPS (Polyphenylene sulfide)

NylonNylon Many othersMany others

Temperature considerationsTemperature considerations


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in thermosets:in thermosets: Curing temperature and timeCuring temperature and time

Glass Transition TemperatureGlass Transition Temperature (T(Tgg))

Heat deflection or distortion temperature;Heat deflection or distortion temperature;

service temperatureservice temperature

Polyester AdvantagesPolyester Advantages


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y gy g

InexpensiveInexpensive

Good water resistanceGood water resistanceAvailable in wet or a few prepreg systemsAvailable in wet or a few prepreg systems

WellWell--understood, easy to work withunderstood, easy to work with

Commonly availableCommonly available

Polyester DisadvantagesPolyester Disadvantages


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y gy g

Weaker than the other resin systemsWeaker than the other resin systems

BrittleBrittle -- low elongation to failure (1%low elongation to failure (1% -- 3%)3%) Shrinkage when curingShrinkage when curing -- up to 7% in someup to 7% in some

casescases

Relatively low max. use temperatures (TRelatively low max. use temperatures (Tgg)) Relatively poor adhesionRelatively poor adhesion

Styrene emissionsStyrene emissions

Toxic smokeToxic smoke

Vinylester AdvantagesVinylester Advantages


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y gy g

Stronger, stiffer than polyesterStronger, stiffer than polyester

Better environmental resistance thanBetter environmental resistance thanpolyesterpolyester

Higher elongation to failure (3%Higher elongation to failure (3% -- 6%); this6%); thismeans itmeans its less brittles less brittle

Less shrinkage when curingLess shrinkage when curing

Higher THigher Tgg Better adhesion than polyesterBetter adhesion than polyester

Vinylester DisadvantagesVinylester Disadvantages


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y gy g

Higher cost than polyesterHigher cost than polyester

Not available as prepregNot available as prepreg

Styrene emissionsStyrene emissions Toxic smokeToxic smoke

No long cure times possible, aNo long cure times possible, adisadvantage when building very largedisadvantage when building very largestructures.structures.

Epoxy AdvantagesEpoxy Advantages


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p y g

Stronger than polyesters or vinylestersStronger than polyesters or vinylesters

Cure times from minutes to years availableCure times from minutes to years available

No styrene emissionsNo styrene emissions

Less shrinkageLess shrinkage Higher THigher Tggss availableavailable

Excellent adhesive propertiesExcellent adhesive properties

Commonly available wet and in prepregCommonly available wet and in prepreg

Epoxy DisadvantagesEpoxy Disadvantages


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Higher costHigher cost

Precise mix ratios mandatoryPrecise mix ratios mandatory Cannot be mixedCannot be mixed hothot

Hardener Vs.Hardener Vs. CatalystCatalyst discussed belowdiscussed below

Toxic smokeToxic smoke

Phenolic advantagesPhenolic advantages


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Good electrical insulating propertiesGood electrical insulating properties

Good chemical resistanceGood chemical resistance Stable at high loads and temperaturesStable at high loads and temperatures

Good fireGood fire--smokesmoke--toxicity performancetoxicity performance Good ablativeGood ablative

Often used in interiorsOften used in interiors

Phenolic disadvantagesPhenolic disadvantages


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Can be difficult to processCan be difficult to process

Brittle; weaker than epoxiesBrittle; weaker than epoxies Poor adhesive characteristicsPoor adhesive characteristics

Curing Polyesters & VinylestersCuring Polyesters & Vinylesters


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Cure initiated by the addition of aCure initiated by the addition of a catalystcatalyst

Methyl Ethyl Ketone PeroxideMethyl Ethyl Ketone Peroxide -- MEKP (liquid)MEKP (liquid)

Benzoyl PeroxideBenzoyl Peroxide BPO (paste)BPO (paste)

Both have significant health & safety concernsBoth have significant health & safety concerns

These initiators kill off inhibitors, and allow the resinThese initiators kill off inhibitors, and allow the resinmolecules to crossmolecules to cross--linklink

Exact mix ratios not criticalExact mix ratios not critical can mixcan mix hothot or mixor mixcoldcold

Mix timing and sequence is criticalMix timing and sequence is critical

Styrene emission problemsStyrene emission problems

Curing EpoxiesCuring Epoxies


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These resins are cured by crossThese resins are cured by cross--linking with alinking with ahardenerhardener, not by adding a catalyst, not by adding a catalyst

Exact mix ratios are critical, especially as oneExact mix ratios are critical, especially as onemoves away from 50/50 mixes;moves away from 50/50 mixes; 2% by weight2% by weight

needed with the strongest aircraftneeded with the strongest aircraft

--gradegrade

systemssystems

OneOne cannotcannot mixmix hothot ororcoldcold

Different hardenerDifferent hardenerspeedsspeeds are available forare available formany epoxy resin systemsmany epoxy resin systems

Epoxy curing temperatureEpoxy curing temperature


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considerationsconsiderations While many areWhile many are roomroom--temptemp curable, almost allcurable, almost all

develop full strength only after a highdevelop full strength only after a high--temptemp

postpost--curecure: 150: 150FF 200200F for 1F for 1--10 hours.10 hours.

Higher cure temperatures also result in a higherHigher cure temperatures also result in a higher

glass transition temperatureglass transition temperature

Outgassing can be an issue in highOutgassing can be an issue in high--temperaturetemperaturecure cyclescure cycles

Crosslinking rate doubles for every 10Crosslinking rate doubles for every 10C (18C (18F)F)temperature increasetemperature increase

Things to watch out forThings to watch out for


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Improper mix ratiosImproper mix ratios By weight or by volumeBy weight or by volume they are different!they are different!

Incomplete mixingIncomplete mixing

Wrong ingredientsWrong ingredients

Wrong mixing sequenceWrong mixing sequence ExothermsExotherms --A good way to get OSHA onA good way to get OSHA on

your case!your case! Excessive moistureExcessive moisture

Old materialsOld materials

The Least You Need to KnowThe Least You Need to Know


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When you laminate, unlike with aluminum,When you laminate, unlike with aluminum, YouYouare the Creator of the material propertiesare the Creator of the material properties dodo

it right!it right! Repairs and assembly cures areRepairs and assembly cures are secondarysecondary

bondsbonds excellent surface preparation is critical!excellent surface preparation is critical!

Errors here are NOT detectable with ANY NDIErrors here are NOT detectable with ANY NDIprocess!process!

Use resins with adequate propertiesUse resins with adequate properties thosethose

approved by the airframe manufacturer ONLY!approved by the airframe manufacturer ONLY!

Structural Properties ResultStructural Properties Result


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From Many Design Choices andFrom Many Design Choices andFabrication ProcessesFabrication Processes

Material ChoicesMaterial Choices FibersFibers

Fiber FormsFiber Forms

ResinsResins

CoresCores Fiber AlignmentFiber Alignment

ProcessProcess

Contact LayupsContact Layups

Vacuum Bagged LayupsVacuum Bagged Layups

Elevated Temperature CureElevated Temperature Cure

Peel Ply UsePeel Ply Use

Practice Safe CompositesPractice Safe Composites


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Epoxy SensitizationEpoxy Sensitization

Through the SkinThrough the Skin

InhalationInhalation Fillers and FibersFillers and Fibers

VaporsVapors

BlindnessBlindness Polyester Activator (MEKP)Polyester Activator (MEKP)

Resin Uncontrolled ExothermsResin Uncontrolled Exotherms

Electrical Motor ShortsElectrical Motor Shorts Carbon DustCarbon Dust

Top 10 ListTop 10 List


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1.1. Protect Your HealthProtect Your Health2.2. Peel Ply Is Your Friend, EXCEPT forPeel Ply Is Your Friend, EXCEPT for

secondary bondline surface preparation!secondary bondline surface preparation!3.3. Mix Epoxy Resins AccuratelyMix Epoxy Resins Accurately4.4. Use The Right Materials When MakingUse The Right Materials When Making

StructureStructure Fiber FinishFiber Finish

Structural ResinStructural Resin

Wet Layup/Honeycomb usually turns out ugly.Wet Layup/Honeycomb usually turns out ugly.

Top 10 List (cont.)Top 10 List (cont.)


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5.5. Secondary Bonds Require Careful PreparationSecondary Bonds Require Careful PreparationCleaning Solvents usually contaminate, not clean!Cleaning Solvents usually contaminate, not clean!

6.6. Epoxies Do Not Reach Their Full PropertiesEpoxies Do Not Reach Their Full PropertiesUnless PostUnless Post--CuredCured

7.7. Only Low Viscosity Resins Will EncapsulateOnly Low Viscosity Resins Will Encapsulate

The Individual Tiny Reinforcement FibersThe Individual Tiny Reinforcement Fibers

8.8. Laminate Only When The Temperature AndLaminate Only When The Temperature AndHumidity Are Correct For The Resin In UseHumidity Are Correct For The Resin In Use

9.9. Vacuum Bagging Improves Material PropertiesVacuum Bagging Improves Material Properties

10.10. Face Sheet To Core Bonds Are Critical!Face Sheet To Core Bonds Are Critical!

More on surface prep for bonding:More on surface prep for bonding:


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NylonNylon peel plies ALL contain releasepeel plies ALL contain releaseagents, usually siliconeagents, usually silicone--based, even thosebased, even thoseadvertised as being heatadvertised as being heat--cleaned!cleaned!

If there was no release agent in them atIf there was no release agent in them at

all, they would never release, and wouldall, they would never release, and wouldhave to be ground off.have to be ground off.

PolyesterPolyesterpeel plies may or may not havepeel plies may or may not haverelease agents in them.release agents in them.



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CoronaCorona--treatedtreated polyester peel plies dopolyester peel plies donot have release agents, but do have anot have release agents, but do have a

limited shelf life, about one year.limited shelf life, about one year. Even these peel plies cause a problem;Even these peel plies cause a problem;

the weave texture of the peel ply leavesthe weave texture of the peel ply leavesthousands of small sharpthousands of small sharp--edged groovesedged groovesin the resin.in the resin.

These grooves are not filled later by theThese grooves are not filled later by theadhesive; the viscosity is too high.adhesive; the viscosity is too high.



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The best solution is GENTLE grit blastingThe best solution is GENTLE grit blastingto remove the peel ply impressions in theto remove the peel ply impressions in thesurface, without damaging the fibers of thesurface, without damaging the fibers of thesurface ply.surface ply.

However, grit blasting with compressed airHowever, grit blasting with compressed airwill contaminate the surface with oil, water,will contaminate the surface with oil, water,

etc. Dry nitrogen works, but is expensive.etc. Dry nitrogen works, but is expensive. SoSo what to do?what to do?



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First of all, NEVER use nylon peel plies onFirst of all, NEVER use nylon peel plies ona surface which will be accepting ana surface which will be accepting anadhesive bond later. Itadhesive bond later. Its fine on nons fine on non--bonding surfaces.bonding surfaces.

Probably the best workable solution is toProbably the best workable solution is touse coronause corona--treated polyester peel plies,treated polyester peel plies,

followed by GENTLE hand sanding tofollowed by GENTLE hand sanding toremove the peel ply weave texture.remove the peel ply weave texture.



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Use cheap sandpaper, which does not haveUse cheap sandpaper, which does not haveantianti--cloggingclogging properties. The expensiveproperties. The expensive

papers are coated with release waxes to helppapers are coated with release waxes to helpthe sanding residue fall off the paper.the sanding residue fall off the paper.

Use a fine grit paper, 320 or higher. You areUse a fine grit paper, 320 or higher. You areNOT trying to getNOT trying to get toothtooth in the bondline. Thisin the bondline. Thiswill break fibers. Bond strengths improve all thewill break fibers. Bond strengths improve all the

way up to 600 grit.way up to 600 grit.

Still more on surface prep for bonding:Still more on surface prep for bonding:


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Do NOT solvent wipe after sanding, dry wipe!Do NOT solvent wipe after sanding, dry wipe!

The final sanding step should be done as closeThe final sanding step should be done as closeas possible to the application of adhesive;as possible to the application of adhesive;preferably within 4 hours. Do not wait overnight.preferably within 4 hours. Do not wait overnight.

The sanding produces aThe sanding produces a high surface energyhigh surface energyon the part. This effect goes away after a fewon the part. This effect goes away after a fewhours, as the broken crosshours, as the broken cross--links on the surfacelinks on the surface

link back together.link back together. Cleanliness in all steps is mandatory!Cleanliness in all steps is mandatory!

How can you tell if your surfaceHow can you tell if your surface

ti i OK?ti i OK?


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preparation is OK?preparation is OK? Try the water break test. However, youTry the water break test. However, you

must dry the parts thoroughly, usingmust dry the parts thoroughly, usingCLEAN white (no printing) paper towelsCLEAN white (no printing) paper towelsand a hair dryer.and a hair dryer.

If the waterIf the wateravoidsavoids an area on youran area on yoursurface, so will the adhesive. Thesurface, so will the adhesive. The

adhesive must uniformly wet out the entireadhesive must uniformly wet out the entirebonding surface.bonding surface.

Water Break TestingWater Break Testing -- beforebefore


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Water break testWater break test after:after:right side clean, left sideright side clean, left side

contaminatedcontaminated


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contaminatedcontaminated

SoSo the details matter!the details matter!


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Creating longCreating long--lasting, durable compositelasting, durable compositeSTRUCTURAL bonds is not easy.STRUCTURAL bonds is not easy.

Even more difficult in aluminum bonding.Even more difficult in aluminum bonding.

The difference between good surfaceThe difference between good surface

preparation and slipshod surfacepreparation and slipshod surfacepreparation means obtaining a joint whichpreparation means obtaining a joint whichwill last many years under load, aswill last many years under load, as

opposed to perhaps only a few months,opposed to perhaps only a few months,especially in a hotespecially in a hot--wet environment.wet environment.

C it D dC it D d


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Composite Damage andComposite Damage andInspection IssuesInspection Issues

Visual inspection is notVisual inspection is notenough!enough!

IntroductionIntroduction


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A vast majority of damage occurs on the

ground. Brittle nature of matrix/fiber combination

contributes to ease of damage. Composites are not as tough as metals,

(dont yield and bend like metals);damage is often hidden to the eye.

Unusual Damage MechanismsUnusual Damage Mechanisms


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To those untrained in these materials,there are unexpected ways to causedamage:

Water ingress into honeycomb cores Paint stripper!

Minor impacts such as tool drops, etc.

Heat, Hydraulic fluid, UV, etc.

Lightning StrikesLightning Strikes


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Bird StrikesBird Strikes


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Impact DamageImpact Damage


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Water DamageWater Damage


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Battle DamageBattle Damage


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JackstandsJackstands


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MidMid--Air CollisionsAir Collisions


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Your flight has arrivedYour flight has arrived

in the gate area!in the gate area!


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in the gate area!in the gate area!

Sheet metal damage assessmentSheet metal damage assessmentis not covered in this presentationis not covered in this presentation


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Damage AssessmentDamage Assessment

I t ff t i ibilit llI t ff t i ibilit ll


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Impact energy affects visibility, as well asImpact energy affects visibility, as well asseverity, of damage:severity, of damage:

High and medium energy impacts, whileHigh and medium energy impacts, whilesevere, are easy to detect.severe, are easy to detect.

Low energy impacts can easily causeLow energy impacts can easily causehiddenhidden damage.damage.

Impact Energy LevelsImpact Energy Levels

Medium Energy ImpactLow Energy Impact0


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CopyrightCopyright

2008 Abaris Training Resources Inc.2008 Abaris Training Resources Inc.

110110

0

0

0

00

+ 45

+ 45

-45

-45

0

9090

High Energy Impact

Through penetrationsmall damage zone

Delamination

Pyramid Pattern Matrix Crack from impact.Delaminations

Back side fiber fracture

0

0

0

00

-45

-45

0

9090

+ 45

+ 45

Why NDI?Why NDI?Delta II launchDelta II launch


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111111

CopyrightCopyright

2008 Abaris Training Resources Inc.2008 Abaris Training Resources Inc.

Primary NDI Technologies usedPrimary NDI Technologies used

in Composite Structuresin Composite Structures


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in Composite Structuresin Composite Structures VisualVisual

Tap TestingTap Testing

UltrasoundUltrasound

XX--RayRay ThermographyThermography

Laser Shearography / InterferometryLaser Shearography / InterferometryAcoustic EmissionsAcoustic Emissions

Visual InspectionVisual Inspection

One can visually detect (to some extent):One can visually detect (to some extent):


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One can visually detect (to some extent):One can visually detect (to some extent):

BurnsBurns

DisbondsDisbonds

DelaminationsDelaminations

ContaminationContamination OverOver--stressed or fractured areasstressed or fractured areas

Paint RemovalPaint Removal

Paint must be removed before a visualPaint must be removed before a visual


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Paint must be removed before a visualPaint must be removed before a visualinspection can be performed.inspection can be performed.

DO NOT USE PAINT STRIPPER!! It willDO NOT USE PAINT STRIPPER!! It willattack andattack and eateat the resin.the resin.

Use gentle hand sanding to remove paint;Use gentle hand sanding to remove paint;DO NOT SAND INTO THE FIBERS!DO NOT SAND INTO THE FIBERS!

Wing impact loading on aft attachWing impact loading on aft attachpoints causes floor to break herepoints causes floor to break here

(Picture courtesy of Cirrus Design)(Picture courtesy of Cirrus Design)


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115115

Composite turns white at the point of

fracture

CopyrightCopyright2008 Abaris Training Resources Inc.2008 Abaris Training Resources Inc.

Look at flat angle toLook at flat angle todetect small defectsdetect small defects


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EffectiveEffective Less Effective OnLess Effective On


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EffectiveEffective

Cheap, .25Cheap, .25 & Up& Up

Less Effective OnLess Effective OnThick LaminatesThick Laminates

WonWont Go Throught Go ThroughCoreCore

Possible FalsePossible FalseReadingsReadings

Must Be Able To HearMust Be Able To Hear

Quiet Area NeededQuiet Area Needed


Wichitech Electronic Tap HammerWichitech Electronic Tap Hammer


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Wichitech Electronic Tap HammerWichitech Electronic Tap Hammer

Ultrasonic InspectionUltrasonic Inspection

AA--ScanScan


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AA ScanScan

PulsePulse--Echo DisplayEcho Display

CC--ScanScan

Through TransmissionThrough Transmission

UltrasonicUltrasonic AA--ScanScan InspectionInspection


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Ultrasonic InspectionUltrasonic Inspection


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Noise From ImperfectionsNoise From Imperfections

Material AttenuationMaterial Attenuation Kevlar Reads Poorly, Carbon Reads BetterKevlar Reads Poorly, Carbon Reads Better Autoclave cured reads better than vacuumAutoclave cured reads better than vacuum

bag curedbag cured

Hidden DelaminationsHidden Delaminations

A-Scan DisplayAA--ScanScan DisplayDisplay

ThroughThrough--transmission ultrasonicstransmission ultrasonics


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ThroughThrough--transmission ultrasonics:transmission ultrasonics:CC--scanscan display of Fdisplay of F--18 carbon18 carbon

fiber upper inner wing skinfiber upper inner wing skin


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XX--Ray InspectionRay Inspection

Sees Changes In DensitySees Changes In Density


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g yg y

May see Delaminations When ViewedMay see Delaminations When ViewedFrom An AngleFrom An Angle

Shows Some InclusionsShows Some Inclusions

Can Show WaterCan Show Water

XX--Ray Inspection of FRay Inspection of F--1818horizontal stabilizerhorizontal stabilizer


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ThermographyThermography

Uses Infrared Video CameraUses Infrared Video Camera


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Sees small changes in temperatureSees small changes in temperature

Can see many kinds of defectsCan see many kinds of defects

Cutting Edge: Pulsed ThermographyCutting Edge: Pulsed Thermography

Computer enhancedComputer enhanced

MOSAIQ SoftwareMOSAIQ Software

Pulsed ThermographyPulsed Thermography

Disbonded Honeycomb Panel


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127127CopyrightCopyright2008 Abaris Training Resources Inc.2008 Abaris Training Resources Inc.

Methods of limitedMethods of limitedvalue in composites:value in composites:


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Eddy CurrentEddy Current Dye PenetrantDye Penetrant

ThoroughlyThoroughly

contaminatescontaminates

laminatelaminate nono

repair possible.repair possible.

AA--300 Vertical Fin Spar Failure300 Vertical Fin Spar Failure


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Not The First TimeNot The First Time


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Problems in Composite NDIProblems in Composite NDI

Hidden DamageHidden Damage more prevalent inmore prevalent in


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composites than in metals.composites than in metals.

Therefore there is more of a requirementTherefore there is more of a requirementfor NDI, but if no one is even aware thefor NDI, but if no one is even aware the

component may be damaged, NDI willcomponent may be damaged, NDI willlikely not be utilized.likely not be utilized.

More ProblemsMore Problems

Water in honeycomb coreWater in honeycomb core


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Can easily be detected if there is a lot ofCan easily be detected if there is a lot of

water.water.

MoistureMoisture not so easy to detect, and oftennot so easy to detect, and oftencauses skins to blow off sandwich corescauses skins to blow off sandwich coresduring highduring high--temperature cured repairs.temperature cured repairs.

Difficult to detect moisture, therefore difficultDifficult to detect moisture, therefore difficult

to know if the component is dry enough toto know if the component is dry enough toproceed with repair.proceed with repair.

Yet More ProblemsYet More Problems

Heat damageHeat damagefE t d t t if i ll i


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Easy to detect if severe, especially inEasy to detect if severe, especially in

fiberglass, but essentially impossible to detectfiberglass, but essentially impossible to detectin carbon fiber if it is less severe but stillin carbon fiber if it is less severe but stillsignificant damage.significant damage.

Resin matrix becomes more brittle, crackResin matrix becomes more brittle, crack--proneprone Caused permanent grounding of a Navy ACaused permanent grounding of a Navy A--66

Intruder after engine fire; no one could determineIntruder after engine fire; no one could determinethe extent of the heat damage to the new allthe extent of the heat damage to the new all--

carbon fiber wing. Led to the writecarbon fiber wing. Led to the write--off of a ~$40off of a ~$40million aircraft.million aircraft.

More Problems StillMore Problems Still

Cannot detect a weak but stillCannot detect a weak but still--stuckstuckdh i b ddh i b d


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adhesive bond.adhesive bond.

Easy to detect destructivelyEasy to detect destructively

Unknown how to detect nonUnknown how to detect non--destructively.destructively.

Big problem, relatively common occurrenceBig problem, relatively common occurrenceAging epoxy degrades, especially hotAging epoxy degrades, especially hot--wetwet

Improper surface preparations commonImproper surface preparations common

Many process control issuesMany process control issues

So this is an Opportunity!So this is an Opportunity!

The industry badly needs the ability toThe industry badly needs the ability toth t th f dh i b dth t th f dh i b d


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measure the strength of an adhesive bondmeasure the strength of an adhesive bond

nonnon--destructively.destructively.

Many organizationsMany organizations manufacturers,manufacturers,

military, airlines, etc.military, airlines, etc. would pay dearly towould pay dearly tohave this capability.have this capability.

Probably the biggest missing link in theProbably the biggest missing link in theadvanced composites field at this time.advanced composites field at this time.

Composite DamageComposite Damage


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Repair TechniquesRepair Techniques

FieldField--level repairs conductedlevel repairs conductedwithout an autoclave.without an autoclave.

IntroductionIntroduction

Damaged composite structures areDamaged composite structures ared fi it l i bldefinitel repairable


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definitely repairable.definitely repairable.

However, there are problems:However, there are problems:

Hidden damage issues, includingHidden damage issues, including

manufacturing defects.manufacturing defects. Unexpected damage sources.Unexpected damage sources.

BestBest repair techniques heavily dependent onrepair techniques heavily dependent on

details of the structuredetails of the structure..

Impact spreads in a coneImpact spreads in a cone--shapedshapedarea from the point of impactarea from the point of impact


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Damage RemovalDamage Removal

Additional damage assessment must beAdditional damage assessment must beperformed after paint removal or Tedlarperformed after paint removal or Tedlar


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performed after paint removal or Tedlarperformed after paint removal or Tedlar

film removal, as hidden damage oftenfilm removal, as hidden damage oftenbecomes more apparent.becomes more apparent.

Damaged composite skin may be removedDamaged composite skin may be removedby careful routing or grinding through theby careful routing or grinding through thedamaged surface.damaged surface.

Diamond Router BitDiamond Router Bit Good forGood forCarbon Fiber and Fiberglass, notCarbon Fiber and Fiberglass, not

for Kevlarfor Kevlar


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Single Helix RouterSingle Helix Router Good forGood forCarbon Fiber and Fiberglass, notCarbon Fiber and Fiberglass, not



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Split Helix Router for KevlarSplit Helix Router for Kevlar


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Sanding DrumSanding Drum Good for CarbonGood for CarbonFiber and Fiberglass, not for KevlarFiber and Fiberglass, not for Kevlar


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Diamond Hole SawDiamond Hole Saw Good forGood forCarbon Fiber and Fiberglass, notCarbon Fiber and Fiberglass, not



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Kevlar Hole Saw with pilot bitKevlar Hole Saw with pilot bit


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Die Grinder with 180 grit diskDie Grinder with 180 grit disk


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Die Grinder with ScotchBriteDie Grinder with ScotchBritepadpad


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For a solid laminate with through damage,For a solid laminate with through damage,routing is recommended.routing is recommended.


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gg

For a sandwich skin, with damage into theFor a sandwich skin, with damage into thecore, routing also works well.core, routing also works well.

For a thick solid laminate with damageFor a thick solid laminate with damageonly on surface plies, use careful sandingonly on surface plies, use careful sandinguntil undamaged plies are reached.until undamaged plies are reached.


Damaged core should also be removedDamaged core should also be removed

Remove damage in circular or ovalRemove damage in circular or oval


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Remove damage in circular or ovalRemove damage in circular or oval

shapes, and do not use sharp corners.shapes, and do not use sharp corners.

If an irregular shape must be used, thenIf an irregular shape must be used, then

round off each corner to as large a radiusround off each corner to as large a radiusas practical.as practical.

Drying laminates, especially coredDrying laminates, especially coredstructures, is crucial for highstructures, is crucial for high--

temperature cured repairs.temperature cured repairs.


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Composite Repair PrinciplesComposite Repair Principles

Taper edges of repair plies in doublers.Taper edges of repair plies in doublers. This is true whether the doubler is to beThis is true whether the doubler is to be

bonded or mechanically fastened and isbonded or mechanically fastened and is


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bonded or mechanically fastened, and isbonded or mechanically fastened, and ismounted inside or outside the skin.mounted inside or outside the skin.

Cross-sections

Avoid stress concentrations

Composite Fastener StylesComposite Fastener Styles

BlindBlind

Access to one side onlyAccess to one side only


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Access to one side onlyAccess to one side only

Cherry / TextronCherry / Textron

HuckHuck

MonogramMonogram

TwoTwo--PartPart

Require access to both sidesRequire access to both sides

HuckHuck

HiHi--LokLok

Blind FastenersBlind Fasteners

Access to one sideAccess to one sideonlyonly


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Pulls stem throughPulls stem throughrivet bodyrivet body

Expands back sideExpands back side

Stem breaks flushStem breaks flush

Sets locking ringSets locking ring

Blind FastenersBlind Fasteners

Access to one sideAccess to one sideonlyonly


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Pulls stem throughPulls stem throughrivet bodyrivet body

Expands back sideExpands back side

Stem breaks flushStem breaks flush

Sets locking ringSets locking ring

Two Part FastenersTwo Part Fasteners

Access From BothAccess From BothSides RequiredSides Required


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HiHi--Shear,HiShear,Hi--Lok,HiLok,Hi--TigueTigue

Lock BoltsLock Bolts

Mechanism FastensMechanism FastensBy Threading OrBy Threading Or

SwagingSwaging

Metallic vs. Composite FastenersMetallic vs. Composite Fasteners


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Bearing Area DramaticallyBearing Area Dramatically

Increased To ReduceIncreased To ReduceTipping and fiber crushingTipping and fiber crushing

Bearing AreaBearing Area

Metallic vs. CompositeMetallic vs. CompositeCountersinksCountersinks

100


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and 130and 130 for composites.for composites.

130

Countersinks Come In TwoTypes; 100 for metals;

MaterialsMaterials

Fasteners For CompositesFasteners For Composites

A282 StainlessA282 Stainless


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TitaniumTitanium

MonelMonel

Corrosion ConsiderationsCorrosion Considerations

Fastener InstallationFastener Installation

Variety Of Installation ToolsVariety Of Installation Tools

Frequently Heavy / CumbersomeFrequently Heavy / Cumbersome


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q y yq y y

Each Manufacturer Has Their Own Go /Each Manufacturer Has Their Own Go /NoNo--Go CriteriaGo Criteria

Fastener RemovalFastener Removal

OEM Removal SystemsOEM Removal SystemsOEM Removal Systems


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Monogram (ComposiMonogram (Composi--lok II)lok II)

Huck InternationalHuck InternationalHuck International

Cherry TextronCherry TextronCherry Textron

YES

YES *

NO


BasicsBasics

Disengage Locking Ring (if blind)Disengage Locking Ring (if blind)


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Drive Out PinDrive Out Pin

Drill Through Head Only Using SlightlyDrill Through Head Only Using SlightlyUndersized BitUndersized Bit

Remove HeadRemove Head

Drive Out ShankDrive Out Shank


BasicsBasics



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Drive Out PinDrive Out Pin

Drill Through Head Only Using SlightlyDrill Through Head Only Using SlightlyUndersized BitUndersized Bit




BasicsBasics



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Drive Out PinDrive Out Pin Drill Through Head Only Using SlightlyDrill Through Head Only Using Slightly

Undersized BitUndersized Bit




BasicsBasics



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BasicsBasics



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BasicsBasics



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Old Methods Cannot Be Used:Old Methods Cannot Be Used:

Grinding HeadGrinding Head


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Heats Rivet ExcessivelyHeats Rivet Excessively

Cold Chisel To Cut Locking RingCold Chisel To Cut Locking Ring

Will Not Cut TitaniumWill Not Cut Titanium

Drilling To Cut Locking RingDrilling To Cut Locking Ring

Risk Slipping / Wandering Off Head On ToRisk Slipping / Wandering Off Head On ToLaminateLaminate


Drill FixtureDrill Fixture

Necessary To Stay Centered & PreventNecessary To Stay Centered & Prevent


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WanderingWandering Several ApproachesSeveral Approaches

Carbide ToolsCarbide Tools RequiredRequired For Cutting TitaniumFor Cutting Titanium

Cobalt May Work For Stainless SteelCobalt May Work For Stainless Steel


Monogram FastenersMonogram FastenersMonogram Fasteners


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Monogram FastenersMonogram FastenersMonogram Fasteners


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Not Well Addressed By MostNot Well Addressed By MostManufacturers


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Manufacturers Exception: MonogramException: Monogram Removal Tools Are CumbersomeRemoval Tools Are Cumbersome

Stick To The BasicsStick To The Basics Disengage Locking RingDisengage Locking Ring

Use Only Carbide ToolsUse Only Carbide Tools

Only Drill Deep Enough To RemoveOnly Drill Deep Enough To RemoveFastener HeadFastener Head

Scarfed (taper sanded) repairsScarfed (taper sanded) repairs

After initial damage removal, we usuallyAfter initial damage removal, we usuallyscarf (taper sand) gently around the repairscarf (taper sand) gently around the repair


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area.area. Rule of thumbRule of thumb -- crude approximationcrude approximation -- is 1/2is 1/2

per ply.per ply.

Lightly loaded structures may be able toLightly loaded structures may be able totolerate a smaller scarf; heavily loadedtolerate a smaller scarf; heavily loaded

structures may require more.structures may require more.

ScarfingScarfing

Scarf distance is often referred to by angles,Scarf distance is often referred to by angles,rather than distance per ply.rather than distance per ply.

20:1 up to as much as 100:120:1 up to as much as 100:1


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The flatter the scarf, the larger the adhesiveThe flatter the scarf, the larger the adhesivebond, and the lower the load per square inchbond, and the lower the load per square inchon the bond.on the bond.

The steeper the scarf, the less undamagedThe steeper the scarf, the less undamagedmaterial is removed.material is removed.

0:10:1 -- Butt joint;Butt joint; :1:1 New PartNew Part

Scarfed RepairsScarfed Repairs

Scarf distance


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Double-sided

Single-sided

Scarf distance

Repair Sequence forRepair Sequence forScarfed Repair:Scarfed Repair:

Inspect for extent of damage:Inspect for extent of damage: VisualVisual

Tap, Ultrasonic, and/or XTap, Ultrasonic, and/or X--raysrays

G b ibl b h id if f iblG t b t ibl b th id if f ibl


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Get best access possible, both sides if feasible.Get best access possible, both sides if feasible.

Remove all damaged and delaminated material.Remove all damaged and delaminated material.

Circular or rounded cornersCircular or rounded corners Grind away scarf angle taper:Grind away scarf angle taper:

Smooth, flat ground surfaceSmooth, flat ground surface

Repair Sequence forRepair Sequence forScarfed RepairScarfed Repair

Determine ply orientations and materials ofDetermine ply orientations and materials oforiginal structure.original structure.

Replace plies:Replace plies:


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Adhesive layer firstAdhesive layer first

One or more filler plies, orientation not important.One or more filler plies, orientation not important.

Repair pliesRepair plies -- match orientations with originalmatch orientations with originalstructure.structure.

Extra pliesExtra plies -- usually orientation matches originalusually orientation matches originalouter ply.outer ply.

Often an outer adhesive layer.Often an outer adhesive layer.

Scarfed Repair sequenceScarfed Repair sequence


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Basics of Vacuum BaggingBasics of Vacuum Bagging

Purpose of Vacuum Bag:Purpose of Vacuum Bag: To provide compaction pressure to laminate or bondTo provide compaction pressure to laminate or bond

Maximum 29.92Maximum 29.92 Hg @ sea levelHg @ sea level O t h f 14 7 PSI @One atmosphere of press re 14 7 PSI @ sea


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One atmosphere of pressure = 14.7 PSI @ seaOne atmosphere of pressure = 14.7 PSI @ sealevellevel

Loss of approx. 1Loss of approx. 1 Hg (.5 psi) per 1000 ft. ofHg (.5 psi) per 1000 ft. of

elevationelevation To extract resin, air, & volatilesTo extract resin, air, & volatiles

BleedBleed excess resin to reduce contentexcess resin to reduce content Distribute resin equally throughout theDistribute resin equally throughout the

laminate/bond jointlaminate/bond joint Remove trapped air, steam, & volatilesRemove trapped air, steam, & volatiles


MaterialsMaterials

Release LayerRelease Layer

Peel PlyPeel Ply

Nylon/release treatedNylon/release treated porousporous


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Nylon/release treatedNylon/release treated--porousporous

Can transfer release agent residue to partCan transfer release agent residue to part--laminatelaminate

Polyester/Corona discharge treatedPolyester/Corona discharge treated

leaves no release agent residue but harder toleaves no release agent residue but harder toremoveremove

Teflon coated fabrics (TFP or TFNP)Teflon coated fabrics (TFP or TFNP)

More expensiveMore expensive--easy to removeeasy to remove--does not transferdoes not transfer


Materials (continued)Materials (continued)

Release filmsRelease films

Solid filmsSolid films


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Solid filmsSolid films Completely restricts resin bleed and limits volatileCompletely restricts resin bleed and limits volatile

extractionextraction

Perforated filmsPerforated films Allows resin/volatile movement through holes in filmAllows resin/volatile movement through holes in film

Hole diameters range from .015Hole diameters range from .015 (pin(pin--prick) to .045prick) to .045 (full(fullhole)hole)

Hole spacing ranges from 1/4Hole spacing ranges from 1/4 to 12to 12 centers incenters incommercial filmscommercial films


Materials (continued)Materials (continued)

FlashFlash--breaker tapebreaker tape

Used to hold ancillary materials in place forUsed to hold ancillary materials in place for


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Used to hold ancillary materials in place forUsed to hold ancillary materials in place forprocessingprocessing--removable after heat and pressureremovable after heat and pressure

Polyester or Kapton film in various widths availablePolyester or Kapton film in various widths available

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Abaris Composites