ACMA Composites 2004, rev A - Eric Greene Associates Inc
Transcript of ACMA Composites 2004, rev A - Eric Greene Associates Inc
Composites 2004
ACMAAmerican Composites
Manufacturing Association
Tampa Convention Center
October 7, 2004
presented by:Eric Greene, Naval Architect, Eric Greene Associates, Inc., [email protected]
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Presentation Overview Session 1 - Composite Materials & Design (2:00 - 3:00)
• Composite Materials• Design Concepts
• Structural Concepts• Design Methodology
Session 2 - Manufacturing Processes (3:00 - 3:45)• Fabrication• Joining Technologies• Facilities
Break (3:45 - 4:00)
Session 3 - Military Applications of Composites (4:00 - 4:30)• SOCOM Maritime Platforms• Other US Navy Applications
Session 4 - Performance of Composite Structures In-Service (4:30 - 5:00)• Inspection & Repair• Future Developments
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Session 1 - Composite Materials & Design (2:00 - 3:00)
• Applications of Marine Composites
• Composite Materials
• Design Concepts• Structural Concepts• Design Methodology
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Safety Enclosed Driver Capsule from Ron Jones Marine and Rendering ofHigh-Speed Hydroplane Built by with Prepreg Material [Ron Jones Marine]
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161’ Motoryacht Evviva Built by AdmiralMarine [Admiral]
150-foot Omohundro carbon Fiber/EpoxyMast for 115' Ted Hood Designed ShallowDraft Sailing Yacht Built by TridentShipworks [photo by the author]
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Samsung Built 37-meter SES Designed by Nigel Gee and Associates using aKevlar® Hybrid Reinforcement for the Hull [DuPont, Oct 1993, Marine Link]
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1966 Hand Lay-Up Mat and Woven Roving1972 Sandwich Construction1974 Alternative Resin Development1981 Advanced Fabrication Techniques1982 Alternative Reinforcement Materials1990 Vacuum Bag Techniques2000 Infusion Methods
Manufacturing Technology Development
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O4COMPOSITESMARINE COMPOSITESMetal & Composites
Metal Composites
Material comes into theshipyard with
properties predetermined
Composites take format the shipyard,
dependent on fabricationmethods and worker skill
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O4COMPOSITESMARINE COMPOSITESSpecific Strength and Stiffness
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O4COMPOSITESMARINE COMPOSITESDirectional Properties of Composites
The strength of composite fibersare dramatically reduced as the angle
to the applied load is increased
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O4COMPOSITESMARINE COMPOSITESRule of Mixtures
Loaddistribution
betweenfiber and
matrix
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O4COMPOSITESMARINE COMPOSITESLaminate Properties
Poisson’s Ratio
Str
engt
hS
tiff
ness
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O4COMPOSITESMARINE COMPOSITESFibers
Comparative Data for Some Reinforcement Fibers
Fiber Densitylb/in3
TensileStrengthpsi x 103
TensileModuluspsi x 106
UltimateElongation
Bulk Cost2003 $/lb
E-Glass .094 500 10.5 4.8% .36-.54S-Glass .090 665 12.6 5.7% 4.00Aramid - Kevlar 49 .052 525 18.0 2.9% 19.00Spectra 900 .035 375 17.0 3.5% 20.00Polyester - COMPET .049 150 1.4 22.0% 1.75Carbon - Aerospace .062-.065 350-700 33-57 0.38-2.0% 15-100Carbon - Recreational .062-.065 550 35 1.5% 5-12
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O4COMPOSITESMARINE COMPOSITESResins
Comparative Data for Some Thermoset Resin Systems (castings)
Resin BarcolHardness
TensileStrengthpsi x 103
TensileModuluspsi x 105
UltimateElongation
Bulk Cost2003 $/lb
Orthophthalic Polyester 42 7.0 5.9 0.91% .75Isophthalic Polyester 46 10.3 5.7 2.0% .86Dicyclopentadiene (DCPD) 54 11.2 9.1 0.86% .77Vinyl Ester 35 11.5 4.9 5.5% 1.10Phenolic 45 1.8% 1.30Epoxy 86D* 8 5.3 7.7% 4.00 * Hardness value for epoxies are typically given on the “Shore D” scale
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O4COMPOSITESMARINE COMPOSITESCores
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O4COMPOSITESMARINE COMPOSITESStructural Comparison Between Metal & Composites
Material Density Tensile Strength Tensile Modulus Ultimate Elongation
lbs/ft3 psi x 103 Mpa psi x 106 Gpa %Resins Orthophthalic Polyester 76.7 7 48.3 .59 4.07 1
Isophthalic Polyester 75.5 10.3 71.1 .57 3.90 2Vinyl Ester 69.9 11-12 76-83 .49 3.38 4-5Epoxy (Gougeon Proset) 74.9 7-11 48-76 .53 3.66 5-6Phenolic 71.8 5.1 35.2 .53 3.66 2
Fibers E-Glass (24 oz WR) 162.4 500 3450 10.5 72.45 4.8S- Glass 155.5 665 4589 12.6 86.94 5.7Kevlar® 49 90 525 3623 18 124.2 2.9Carbon-PAN 109.7 350-700 2415-4830 33-57 227-393 0.38-2.0
Cores End Grain Balsa 7 1.320 9.11 .370 2.55 n/aLinear PVC (Airex R62.80) 5-6 0.200 1.38 0.0092 0.06 30Cross-Linked PVC (Diab H-100) 6 0.450 3.11 0.0174 0.12 n/aHoneycomb (Nomex® HRH-78) 6 n/a n/a 0.0600 0.41 n/aHoneycomb (Nidaplast H8PP) 4.8 n/a n/a n/a n/a n/a
Laminates Solid Glass/Polyesterhand lay-up 96 20 138 1.4 9.66 n/aGlass/Polyester Balsa Sand. 24 6 41 0.4 2.76 n/aGlass/VE PVC Sand, SCRIMP 18 6 41 0.4 2.76 n/aSolid Carbon/Epoxy fil wound 97 88 607 8.7 60 n/aCarbon/Epoxy Nomex prepreg 9 9 62 0.5 3.45 n/a
Metals ABS Grd A (ASTM 131) 490.7 58 400 29.6 204 21ABS Grd AH (ASTM A242) 490.7 71 490 29.6 204 19Aluminum (6061-T6) 169.3 45 310 10.0 69 10Aluminum (5086-H34) 165.9 44 304 10.0 69 9
Wood Douglas Fir 24.4 13.1 90 1.95 13.46 n/aWhite Oak 39.3 14.7 101 1.78 12.28 n/aWestern Red Cedar 21.2 7.5 52 1.11 7.66 n/aSitka Spruce 21.2 13.0 90 1.57 10.83 n/a
Note: The values used in this table are for illustration only and should not be used for design purposes. In general, strength is defined as yield strengthand modulus will refer to the material's initial modulus. A core thickness of 1" with appropriate skins was assumed for the sandwich laminates listed.
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O4COMPOSITESMARINE COMPOSITESComposite Materials Summary
• The physical properties of composite materials are a function ofprocessed reinforcement and resin combinations
• Metals are isotropic with equal properties in all directions -composites have properties that vary with direction
• Carbon fibers have excellent in-plane properties when loads alignwith fibers - E-glass laminates are more damage tolerant
• Large marine structures have traditionally been built with E-glass -long-term experience with carbon fiber is limited
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O4COMPOSITESMARINE COMPOSITESMechanical Strength
Basic• Live Loads• Dead Loads• Liquid/Tank and Cargo
Sea Environment• Hull Girder Bending• Passing Waves• Heel, Pitch and Other Ship Motions• Green Seas
Operational & Extreme• One-Time Extreme Conditions (such as flooding)
Combat (for Military Vessels)• Shock• Airblast• Small Caliber Weapons• Explosive Detonation “Structural Design Manual For Naval Surface Ships”,
NAVSEA 0900-LP-097-4010, December 1976.
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O4COMPOSITESMARINE COMPOSITESDesign Tools
10 meters 100 meters 300 meters
Exp
erie
nce
Bas
eDesign Tools Metal Ships Composite Ships
Isotropic versusAnisotropic Behavior
not applicable Quasi-IsotropicBehavior Assumedfor Large Structures
Upper Limit forClassification SocietyRules
typically 400meters
typically 60 meters
Status of Available FEAPrograms
ProgramsSpecific toShipStructuresAvailable
Dynamic, Out-of-Plane Loads not YetWell Modeled for ShipStructures
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O4COMPOSITESMARINE COMPOSITESDesign Methodology
10 meters 100 meters 300 meters
DesignMethodology
Metal Ships CompositeShips
Rule-Based DesignUsing Empirical Data
Good ExperienceBase for All Vessels
Good ExperienceBase for SmallVessels
Panel Design Basedon Slamming Loads
Only Used forSmaller Vessels andTypicallly forAluminum Only
Process Used forHigh Speed Craft
Midship SectionDesign Based onStiffness and Strength
Traditional Methodfor Large Ships
Method notGenerally Applied
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O4COMPOSITESMARINE COMPOSITESHull as a Longitudinal Girder
Vessel in HoggingCondition
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O4COMPOSITESMARINE COMPOSITESSlamming
) = DisplacementLw = LengthBw = Beam
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O4COMPOSITESMARINE COMPOSITESDesign Tool Summary
• Design tools for large marine structures are more mature formetals than composites
• Composite laminates have 26 engineering parameters that need tobe characterized with mechanical testing
• Composites do not have a “plastic” failure region - interlaminarfailures and cracking precedes catastrophic failure
• There are numerous shear, tensile and compressive failure modesfor composite structures
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Stresses and Deflections due toMembrane Effects
Maximum In-Plane Stress inBeams Subject to Bending
Maximum Shear Stress in BeamsSubject to Bending
Bending Stresses in Panels
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O4COMPOSITESMARINE COMPOSITESHat-Stiffened Solid Laminate
SkinLow
DensityCore
Best Suited for:
• Resisting in-planeloads
• Use with thick-skinned, E-glasslaminates
• Maximumpunctureresistance
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O4COMPOSITESMARINE COMPOSITESSandwich Laminate
Skin
Skin
LowDensity
Core
Best Suited for:
• Resisting out-of-planeloads
• Use with higherstrength/modulusskins
• Maximuminsulationcharacteristics
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Comparison of Solid & SandwichLaminates for Out-of-Plane Loads
t 2t4t
Relative Stiffness 100 700 3700
Relative Strength 100 350 925
Relative Weight 100 103 106
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O4COMPOSITESMARINE COMPOSITESCompressive Failure Modes
Critical Length for Euler Buckling FormulaBased on End Condition (above)
Compressive Failure Modes ofSandwich Laminates (left)
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Longitudinally-Stiffened Panels in Compression
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Transversely-Stiffened Panels in Compression
Transversely StiffenedPanel (above) andBuckling Modes (below)[Smith, BucklingProblems in the Designof Fiberglass ReinforcedPlastic Ships]
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O4COMPOSITESMARINE COMPOSITESHat Stiffeners
Example of asingle skin FRPstiffener to illustratethe designprocess takenfrom USCG NVICNo. 8-87
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Structural Concept Summary
• Hat-stiffened, solid laminates built as monolithic structures offerthe greatest amount of primary axis reinforcements to resist hullgirder bending moments
• Solid laminates are easier to inspect for structural damage
• Sandwich laminates are the most efficient structures for resistingout-of-plane loads
• Sandwich laminates offer good insulation properties and a reserveinner skin to prevent flooding
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Consider life-cyclerequirements of the vessel
to determine expectedwave encounter in termsof height and frequency
Design Methodology
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USCG 47-foot Motor Lifeboat Larson 98 Model 226 LXI Advertised for Sale: “used very little”
Determine In-Service Profile
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Consider life-cyclerequirements of the vessel
to determine expectedwave encounter in termsof height and frequency
DEVELOP DESIGN PRESSUREHull GeometryVessel SpeedIn-Service ConditionsDesign Criteria
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Three-Dimensional Slamming Simulation by Germanischer Lloyd AG
Develop Design Pressure
Pressures Recorded by Heller and Jasper
on Patrol Craft at 28 Knots
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Rule-Based Design Pressure
From ABS 1978 Rules for Reinforced Plastic Vessels, Section 7
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DEVELOP DESIGN PRESSUREHull GeometryVessel SpeedIn-Service ConditionsDesign Criteria
Consider life-cyclerequirements of the vessel
to determine expectedwave encounter in termsof height and frequency
CONSTRUCTIONSolid or SandwichOne-Off or Production
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O4COMPOSITESMARINE COMPOSITESConstruction Method
Prepreg/Nomex Honeycomb Core Construction of Hydroplane at Ron Jones Marine
Hand Layup of Solid Laminate Hullat Westport Marine
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O4COMPOSITESMARINE COMPOSITESCONSTRUCTION
Solid or SandwichOne-Off or Production Consider life-cycle
requirements of the vesselto determine expected
wave encounter in termsof height and frequency
INITIAL MATERIAL SELECTIONReinforcementResinCore
DEVELOP DESIGN PRESSUREHull GeometryVessel SpeedIn-Service ConditionsDesign Criteria
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O4COMPOSITESMARINE COMPOSITESInitial Material Selection
Parameter E-Glass Carbon Kevlar®
Workability Good Fair FairCost Excellent Poor FairStatic Strength Good Excellent GoodDynamic Strength Good Good ExcellentElevated Temperature Performance Good Good Fair
Reinforcements
Parameter Polyester Vinyl ester EpoxyWorkability Excellent Excellent GoodCost Excellent Good FairStatic Strength Fair Good ExcellentDynamic Strength Fair Good GoodElevated Temperature Performance Fair Good Good
Resins
Parameter Balsa PVC FoamWorkability Good GoodCost Excellent GoodStatic Strength Good FairDynamic Strength Fair GoodElevated Temperature Performance Good Poor
Cores
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BULKHEAD SPACING
LONGITUDINAL SPACING
Consider end conditions ofpanel at bulkhead and
stiffener attachment points
Optimize transverse andlongitudinal spacing
based on strength andlayout requirements
DETERMINE PANEL SIZEAspect RatiosDimensions
CONSTRUCTIONSolid or SandwichOne-Off or Production Consider life-cycle
requirements of the vesselto determine expected
wave encounter in termsof height and frequency
INITIAL MATERIAL SELECTIONReinforcementResinCore
DEVELOP DESIGN PRESSUREHull GeometryVessel SpeedIn-Service ConditionsDesign Criteria
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O4COMPOSITESMARINE COMPOSITESDetermine Panel Size
Stress Coefficient as a Function of Panel Aspect Ratio from MARINE COMPOSITES
ab
Bottom Panel Geometry ShowingAspect Ratio and End Conditions
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BULKHEAD SPACING
LONGITUDINAL SPACING
Consider end conditions ofpanel at bulkhead and
stiffener attachment points
Optimize transverse andlongitudinal spacing
based on strength andlayout requirements
DETERMINE PANEL SIZEAspect RatiosDimensions
CONSTRUCTIONSolid or SandwichOne-Off or Production Consider life-cycle
requirements of the vesselto determine expected
wave encounter in termsof height and frequency
INITIAL MATERIAL SELECTIONReinforcementResinCore
DEVELOP DESIGN PRESSUREHull GeometryVessel SpeedIn-Service ConditionsDesign Criteria
ALLOWABLE DEFLECTIONOutfitting ConsiderationsMaterial Strain Limits
Consider Dynamicversus
Static MaterialProperties ALLOWABLE LAMINATE
STRESSIn-Plane & ShearMembrane Effects
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O4COMPOSITESMARINE COMPOSITESStresses and Deflections in Panels
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ALLOWABLE LAMINATE STRESSIn-Plane & ShearMembrane Effects
CONSTRUCTIONSolid or SandwichOne-Off or Production Consider life-cycle
requirements of the vesselto determine expected
wave encounter in termsof height and frequency
INITIAL MATERIAL SELECTIONReinforcementResinCore
ALLOWABLE DEFLECTIONOutfitting ConsiderationsMaterial Strain Limits
Consider Dynamicversus
Static MaterialProperties
BULKHEAD SPACING
LONGITUDINAL SPACING
Consider end conditions ofpanel at bulkhead and
stiffener attachment points
Optimize transverse andlongitudinal spacing
based on strength andlayout requirements
DETERMINE PANEL SIZEAspect RatiosDimensions
DEVELOP DESIGN PRESSUREHull GeometryVessel SpeedIn-Service ConditionsDesign Criteria
COREMaterialDensityThickness
RESINStrengthUltimate Elongation
REINFORCEMENTCompositionArchitecture & ThicknessOrientation
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O4COMPOSITESMARINE COMPOSITESRefine Material Selection based on Strain Limits
First Ply Failure Based on First Play Critical Strain Limits from the ABS Guide forBuilding and Classing High-Speed Craft
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O4COMPOSITESMARINE COMPOSITESRefine Material Selection based on Stress Limits
Skin Section Modulus Based on Applied Failure Momentfrom the ABS Guide for Building and Classing High-Speed Craft
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REINFORCEMENTCompositionArchitecture & ThicknessOrientation
RESINStrengthUltimate Elongation
COREMaterialDensityThickness
ALLOWABLE LAMINATE STRESSIn-Plane & ShearMembrane Effects
BULKHEAD SPACING
LONGITUDINAL SPACING
Consider end conditions ofpanel at bulkhead and
stiffener attachment points
Optimize transverse andlongitudinal spacing
based on strength andlayout requirements
CONSTRUCTIONSolid or SandwichOne-Off or Production Consider life-cycle
requirements of the vesselto determine expected
wave encounter in termsof height and frequency
DETERMINE PANEL SIZEAspect RatiosDimensions
INITIAL MATERIAL SELECTIONReinforcementResinCore
ALLOWABLE DEFLECTIONOutfitting ConsiderationsMaterial Strain Limits
Consider Dynamicversus
Static MaterialProperties
BOTTOMLAMINATE
DEVELOP DESIGN PRESSUREHull GeometryVessel SpeedIn-Service ConditionsDesign Criteria
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O4COMPOSITESMARINE COMPOSITESDevelop Laminate Schedule
Forces Perpendicular to PanelSurface due to Hydrostatic Pressure
and Wave Slamming Loads
Typical Laminate Designation
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O4COMPOSITESMARINE COMPOSITESDesign Summary
• Composites offer the potential to “highly engineer” a structurewhen load paths are well defined
• Long-term experience with large, composite marine structures islimited to E-glass laminates
• In-plane loads dominate for ships - out-of-plane loads drive thedesign of boats
• Sophisticated design tools for composite structures have beendeveloped for the aerospace industry but are immature for large,marine structures
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Session 2 - Manufacturing Processes(3:00 - 3:45)
• Manufacturing Concepts
• Process Descriptions
• Joining Technologies
• Facilities
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O4COMPOSITESMARINE COMPOSITESUS Navy Processing Goals
Naval Surface Warfare Center, Carderock DivisionMarine Composites Branch, Code 655
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Fabrication• Non-autoclave, inexpensive tooling,
low voids, high fiber content,scaleable
• Vacuum Assisted Resin Transfer Molding (VARTM)
• SCRIMP• Recirculation Molding• Low Temp Prepreg• UV Cure Resins
Materials• E-glass, S2-glass, carbon• Vinyl-ester, polyester, phenolic• Woven roving, heavy fabrics,
stitched uni, mat• Balsa, foam
Dr. Gene Camponeschi, NSWCCD
Sandwich Panel Being Fabricated byNorthrop Grumman Ship Systems
Using the SCRIMP Method
NSWCCD Approach forBuilding Superstructures
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One-Off Construction
with WoodBatten Frame
ProductionConstructionfrom FemaleMolds
PanelConstructionwith SecondaryBonds
Manufacturing Concepts
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Production Female MoldsThe process of creating a three-dimensional hull shape generated by adesigner on paper into a full-scale solidform that can be reproduced is called“Mold Making”
Mold - Tool used to reproduce parts
Plug - Copy of part used to produce mold
Female Mold - Concave form used toproduce convex shape
Male Mold - Mold that resembles final part.
Release Agent - A compound applied to themold that allows a cured part to be removed
Plug
Mold on Plug
FinishedSurfaces
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O4COMPOSITESMARINE COMPOSITESCNC Cut Plugs Improve Plug Fabrication
Vectorworks CNC Milling Machine
CAD to CNC opens newpossibilities in boat design
and engineering
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O4COMPOSITESMARINE COMPOSITESLarge Female Molds
Two Part Female Mold Large Female Mold with Stiffeners
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O4COMPOSITESMARINE COMPOSITES
Bulkhead
DeckAdhesive
Interior Corner Detail
Process developed under MARITECH BAA 94-44
Modular Topside Construction
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O4COMPOSITESMARINE COMPOSITESHull Construction using Modular Panels
ModularPanel Secondary
Bond
Visby Class Corvette , Captain Thomas Engevall, US Naval Institute Proceedings, March 1999
Modular hull construction with panels results ingreater control over panel quality
Overall hull girder strength is dependent upon thequality of secondary bonds
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Manufacturing Concept Summary
• Monolithic hull construction from a large mold currently haspractical limits around 65 meters
• Monolithic construction results in the strongest hull girderstrength resulting from continuous reinforcement along the lengthof the vessel
• Modular construction with panels affords greater QA/QC potentialat the component level but places a premium on assembly andjoining technology
• Modular construction is attractive for topside structure thatrequires very flat surfaces and is not subject to “global” loads
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O4COMPOSITESMARINE COMPOSITESManufacturing Processes
• Chopper Gun Technology
• Hand Layup of Rolled Goods
• Sandwich Construction
• Vacuum Bagging Techniques
• Closed Molding– Infusion Methods– RTM
• Prepreg Construction
• Preform Technology
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O4COMPOSITESMARINE COMPOSITESChopper Gun Technology
Roving Chopper
Resin and catalyst nozzles
Cutting wheel with blades
Roving Chute
Feed wheelOptional Inserts
Optional Inserts
Roving guideTensioning Wheel
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O4COMPOSITESMARINE COMPOSITESHand Lay-Up
Workers Laminate Side of Large Hull
Workers Consolidate Reinforcements fromImpregnator
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O4COMPOSITESMARINE COMPOSITESImpregnator-Assisted Open Molding
Schematic of Impregnator Impregnator on Overhead Gantryfor Open Molding of Large Hulls
at Westport Shipyard
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Sandwich Construction
Typical Sandwich Construction Details
Sandwich construction requires addedattention to areas of stress concentration
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Sandwich Construction Installation Goals
• Establish a consistent bondline (thickness of bedding compoundor resin-rich chopped strand mat between core and skins),
• Eliminate voids in the bondline and the core,
• Ensure that bedding material co-cures with resin used to primethe core,
• Use plain sheets with bleeder holes instead of kerfed sheets where possible,
• Build a test panel to ensure that proper materials and process variables are being used, and
• Limit the exposure time of the core to wet resin and bedding compound.
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O4COMPOSITESMARINE COMPOSITESVacuum Bagging
Vacuum BagSealant Tape
Vacuum Valve(Through BagConnection)
Quick Disconnect
Vacuum Bagging FilmHose
Breather/Bleeder
Release Film
Peel Ply
MoldRelease
PressureSensitive Tape
Illustration courtesy of AIRTECH
Laminate
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O4COMPOSITESMARINE COMPOSITESInfusion Methods
Manufacturing composite parts by “Infusion” methods implies that resinis transported by vacuum to dry reinforcement in a closed-moldprocess. Configuration of molds and methods for transporting resindistinguish each individual process. Some advantages that all infusionmethods have over open mold hand lay-up are:
• Improved part consistency as wet-out is not dependent on theskill of the laminator,
• Better work environment because resin isn’t being handleddirectly
• Reduced hazardous air pollutants (HAPs) in the form of styrene
• Ability to achieve higher fiber content laminates
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O4COMPOSITESMARINE COMPOSITESSurface Infusion
SCRIMP™ is a patented surface infusion process that uses avacuum bag that is placed over the dry lay-up and sealed to the tool.The part is then placed under vacuum and resin is introduced intothe part via a resin inlet port and distributed through the laminate viaa flow medium and series of channels, saturating the part.
Schematic of the Patented SCRIMPTM Surface Infusion Method
A Deck being Infusedby the SCRIMPTM Method
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O4COMPOSITESMARINE COMPOSITESInterlaminar Infusion
Interlaminar infusion introduces the resin at the center of the laminatestack, instead of the surface. As a result, the infusion media becomespart of the finished product.
Boat Hull BeingFabricated Using
the InterlaminarInfusion Method
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O4COMPOSITESMARINE COMPOSITES
Resin Transfer Molding (RTM)
Resin Transfer Molding (RTM) uses high pressure to introduce resininto two-sided molds. The RTM process can be highly automated forquick cycle times and to handle the bulky tooling associated with theprocess.
RTM molds are typically bulky in nature to handle the relatively highpressures associated with this process. Steel or aluminum materialsare usually used to produce molds that are designed for multiplecycles without maintenance. The molds usually incorporatealignment pins or some sort of location method to assure the toolsself locate in the proper position every time. The molds are typicallyclamped together using hydraulic presses or bars and clamps. Dueto the high costs associated with the tooling, this process is typicallyreserved for high volume parts.
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O4COMPOSITESMARINE COMPOSITESPrepreg Construction
Prepreg Material Placedin Mold
Prepreg Material ConsolidatedPrior to Cure
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O4COMPOSITESMARINE COMPOSITESPreform Technology
A preform is an assembly of dry reinforcementheld together some way in a form that closelyresembles the final geometry. In the case ofpreforms used for boat stiffeners, the fiber isheld in place by an expanded foam core.
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O4COMPOSITESMARINE COMPOSITESManufacturing Methods Summary
• Long-term experience with composite hull structures in the 20 - 50meter size range is based on hand lay-up construction methods
• Infusion methods have demonstrated the ability to produce lowcost, high quality composite naval structures
• Aerospace manufacturing methods, such as prepreg technology,are not suitable for large marine structures because of materialprocessing requirements
• All composite processing methods are highly dependent uponskill of the worker
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O4COMPOSITESMARINE COMPOSITESJoining of Composite Panels
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O4COMPOSITESMARINE COMPOSITESAdhesively Bonded Joints
Structural adhesives, such as methacrylate and epoxy aregaining wider acceptance in the boat building industry for thefollowing reasons:
• Little or no surface preparation required beyond cleansurface
• Bonds are more durable than structural putties.
• Product dispensing equipment makes handling easier
• Labor savings can offset higher material cost (as compared to structural putties mixed in the shop)
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O4COMPOSITESMARINE COMPOSITESHull-to-Deck JointsThere are about as many specific ways to create an effective hull-to-deckjoint as there are builders. Whether adhesive or fiberglass is used tocreate the watertight joint, some basic principles should be kept in mind:
• The effectiveness of the joint will be proportional to the width of themating surface area so care should be exercised when trimming hull and deck flanges
• Adhere to prescribed flange and tabbing laminate schedule
• Building good joints in tight corners is difficult - use structural putties
• Flat mating surfaces will create a consistent bondline
• Some adhesives do not require sanding of mating surfaces. However, mating surface should always be clean regardless of bonding method
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O4COMPOSITESMARINE COMPOSITESJoining Composites to Metals
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Joining Technology Summary
• In-plane strength of secondary bonds can never match theprimary laminate
• Automation techniques not as mature as metalconstruction
• Surface preparation, laminating environmental conditionsand worker skill significantly influence the strength ofcomposite material structural joints
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O4COMPOSITESMARINE COMPOSITES
Typical Composite Ship Construction Facility
Hull Assembly Building
Materials Storage
TradeShops
Outfitting
Hull Assembly BuildingRepresents Major ShipyardCapital Investment:
• Facility must supportmultiple hulls -10,000 m2 minimum
• Atmosphericemissions control tomeet local standardsrequired
• Environmentallycontrolled facilityrequired, includingHVAC, centralvacuum and firesuppression
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O4COMPOSITESMARINE COMPOSITESTypical Composite Boat Construction Facility
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10 meters
Steel Vessels Composite Vessels
Appr
oxim
ate
Num
ber o
f Shi
pyar
d Fa
cilit
ies
Wor
ldw
ide
10
100
1000
100 meters 300 meters
Notional Worldwide NavalComposite Construction Capability
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O4COMPOSITESMARINE COMPOSITESFacilities Summary
• Laminating must be done in an environmentally controlled facility,including HVAC, central vacuum and fire suppression
• Infrastructure shipyard improvements may also include:
Raw material storage areaHAZMAT containment areaAcetone reclamation areaQA/Test Facility
• Composite construction facilities must be segregated from steelshipbuilding operations due to contamination and fire hazards
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O4COMPOSITESMARINE COMPOSITES
Break: (3:45 - 4:00)
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Military Applications of Composites (4:00 - 4:30)
• Primary Hull Structure• SOCOM Maritime Platforms• Boats & Minehunters
• Superstructure
• Foils and Appendages• Surface Ships• Submarines
• Shipboard Components
Session 3
page 87
O4COMPOSITESMARINE COMPOSITES
11- Meter RIBSOCOM Platforms
Length: 36 feetSpeed: 45 knots+
Displacement: 18,500 pounds (full load)Number in Inventory: 72
Builder: United States Marine, New Orleans, LAYears Manufactured: 1998 - present
Resin System: Vinyl EsterFiber System: E-glass & Kevlar
Core: Linear & Cross-Linked PVCManufacturing Process: Hand Layup, vacuum assist
page 88
O4COMPOSITESMARINE COMPOSITES
Light Patrol Boat (PBL)SOCOM Platforms
Length: 25 feetSpeed: 30 knots+
Displacement: 6,500 poundsBuilder: Boston Whaler
Resin System: polyesterFiber System: E-glassCore (if used): urethane
Manufacturing Process: Hand layup, injected core
page 89
O4COMPOSITESMARINE COMPOSITES
River Patrol Boat (PBR)SOCOM Platforms
Length: 32 feetSpeed: 30 knots +
Displacement: 17,500 poundsNumber in Inventory: 24
Builder: United Boatbuilders, Bellingham, WAYears Manufactured: 500 built starting in 1966
Resin System: polyesterFiber System: E-glassCore (if used): none
Manufacturing Process: Hand layup
page 90
O4COMPOSITESMARINE COMPOSITES
Swimmer Delivery VehicleSOCOM Platforms
Length: 22 feetSpeed: 6 knotsBuilder: Composites by Columbia Research Corporation, Panama City, FL
Resin System: Vinyl esterFiber System: E-glassCore (if used): PVC
Manufacturing Process: Hand layup with vacuum assist for cores
page 91
O4COMPOSITESMARINE COMPOSITES
Advanced Swimmer Delivery SystemSOCOM Platforms
Northrop Grumman’s 65-footAdvanced SEAL Delivery System
Length: 65 feetSpeed: 8 knots+
Displacement: 110,000 poundsNumber in Inventory: 1
Builder: Composites by Goodrich, Jacksonville, FLYears Manufactured: 2001
Resin System: Vinyl ester, rubber toughened for noseFiber System: E-glass with some carbon (carbon being phased out)
Manufacturing Process: VARTM and prepreg for nose
page 92
O4COMPOSITESMARINE COMPOSITES
BoatsPrimary Structure
Members ofInshore
Boat UnitSeventeen
(IBU 17)Patrol theWaters of
ApraHarbor,
Guam
At sea Aboard USS BlueRidge (LCC 19) Sailors
Practice Deployment of Ship’sSmall Boats
page 93
O4COMPOSITESMARINE COMPOSITESPrimary Structure
OSPREY Class Minehunter
page 94
O4COMPOSITESMARINE COMPOSITESSuperstructure
Helicopter Hanger for DDG 51 Flt IIA
Composite Helicopter Hanger for DDG 51 Flight IIA Destroyer Built at Northrop Grumman Ship Systems’ Gulfport Facility
Scheduled to be Installed on DDG 100
page 95
O4COMPOSITESMARINE COMPOSITES
Arrangement of GRP DeckhouseProposed for the SSTDP SealiftShip [Scott Bartlett, NSWC]
French LA FAYETTEClass Frigate ShowingArea Built with Balsa-Cored Composites[DCN Lorient, France]
Superstructure
page 96
O4COMPOSITESMARINE COMPOSITES
Forward Director RoomBuilt by Northrop
Grumman’s El SegundoFacility as Technology
Demonstrator for DDG 51under ManTech Funding
DDG 51 Forward Director RoomSuperstructure
page 97
O4COMPOSITESMARINE COMPOSITES
Surface ShipsFoils & Appendages
Composite MCM Rudder Built by StructuralComposites Shown During Shock Trials
Composite Rudder under Developmentfor Naval Surface Combatants
page 98
O4COMPOSITESMARINE COMPOSITES
SubmarinesFoils & Appendages
AdvancedCompositeSailEnvisionedfor VirginiaClassSubmarines(top left) and1/4-ScalePrototypeBuilt bySeemannComposites(bottom left)
Composite Submarine BowDome Produced by
Goodrich Composites
page 99
O4COMPOSITESMARINE COMPOSITES
Structural Machinery Functional Topside Superstructure Piping Shafting OverwrapsMasts Pumps Life Rails/LinesStacks Valves HandrailsFoundations Heat Exchangers Bunks/LockersDoors Strainers Tables/WorktopsHatches Ventilation Ducts InsulationLiferails Fans, Blowers PartitionsStanchions Weather Intakes Seachest StrainersFairings Propulsion Shafts Deck GratingBulkheads Tanks Stair TreadsPropellers Gear Cases Grid GuardsControl Surfaces Diesel Engines Showers/UrinalsTanks Electrical Enclosures Wash BasinsLadders Motor Housings Water ClosetsGratings Condenser Shells Mast Stays/Lines
Proposed Shipboard Applications for Composites
page 100
O4COMPOSITESMARINE COMPOSITES
Bulkheads, Nonstructural
Priority Medium
Opportunity Opportunity to reduce cost and weight whileimproving fire resistance
TechnicalIssues
Fire, cost, supportability
Previous Work Currently use Nomex/phenolic sandwich
Return onInvestment
Medium
Webcore Hybrid Fabric-Web/Strut-Web
Core with Pre-AttachedFabric Proposed for Navy
SBIR Door Project
page 101
O4COMPOSITESMARINE COMPOSITES
CHT Systems
Priority High
Opportunity Eliminate severe corrosion and makemaintenance easier
TechnicalIssues
Fire; integrate with existing system elements
Previous Work Navy has fielded prototype compositesystems. The U.S. Navy is now specifyingGRP (fiberglass) piping and ladders for useinside the CHT tank, as this material holdsup extremely well in the sewageenvironment.
Return onInvestment
Medium
U.S. Navy Type III Marine SanitationDevice [US Navy ShipboardEnvironmental Information
Clearinghouse]
page 102
O4COMPOSITESMARINE COMPOSITES
Deck Grating
Priority High
Opportunity Eliminate corrosion and related maintenanceand safety issues
TechnicalIssues
Fire and strength
Previous Work ERM-7 has fielded composite grating on 4ships; numerous unauthorized replacementsin the fleet.
NAVSEA Drwg 803-6983499, GRP DeckGrating specifies MODAR resin – partsexpected to be in supply system late FY 03
Return onInvestment
High
Composite Deck Grating onFFG-58 USS Samuel B. Roberts
page 103
O4COMPOSITESMARINE COMPOSITES
Electrical Enclosures
Priority High
Opportunity Reduce corrosion and related maintenance
TechnicalIssues
Fire and impact resistance
Previous Work ERM-7 is in the process of certifying ULTEM2300 electrical enclosures
Return onInvestment
High
Typical Corrosion-Related Failure(above) and ULTEM 2300 Box
Molded by Glenair (below)
page 104
O4COMPOSITESMARINE COMPOSITES
Fairings
Priority High
Opportunity Metal rope guards difficult to replaceunderwater
TechnicalIssues
Fastener interface
Previous Work Composite propulsion shaft rope guardsinstalled on Aircraft Carriers showing:
• Less than ½ the cost and weight oforiginal Cu-Ni
• Bolt-on vs. weld-on• Easy waterborne removal/install gives full
access to stave bearings & zincs
Return onInvestment
High
Installed CompositeFairwaters (NAVSEA 05M3)
page 105
O4COMPOSITESMARINE COMPOSITES
Fans & Blowers
Priority High
Opportunity Reduced corrosion, easier to maintain &quieter
TechnicalIssues
Fire, operability and strength
Previous Work NAVSEA PMS 400D32 is pursuingcomposite fans via SBIR & ManTechprograms
Return onInvestment
High
Typical Axial Fan
page 106
O4COMPOSITESMARINE COMPOSITES
Foundations
Priority High
Opportunity Severe corrosion on saltwater pumpfoundations is major maintenance issue andcontributes to machinery vibration; potentialto make machinery "quieter"
TechnicalIssues
Fire and shock
Previous Work Brunswick Defense built a filament-woundfoundation that was tested at NSWCCD
Return onInvestment
Medium
Filament Wound MachineryFoundation by Brunswick Defense
page 107
O4COMPOSITESMARINE COMPOSITES
Helicopter Hanger Doors
Priority High
Opportunity Reduced corrosion maintenance andmachinery maintenance from less weight
TechnicalIssues
Strength and fire resistance
Previous Work Seemann Composites and BIW havedeveloped a composite helicopter door forDDG 51 Flt IIA. A composite helicopterhanger is scheduled to be installed on DDG-100.
Return onInvestment
Medium
Composite Helicopter Hanger First ArticleDoor (above) and Operational Test Jig
(below) [Seemann Composites]
page 108
O4COMPOSITESMARINE COMPOSITES
Louvers
Priority High
Opportunity Reduce maintenance and improve stealth
TechnicalIssues
Cost, certification and durability
Previous Work Composite louvers developed for the DDG51 class destroyers
Return onInvestment
High
Radar Absorbing Composite LouverDeveloped for the
DDG 51 Class Destroyers
page 109
O4COMPOSITESMARINE COMPOSITES
Masts
Priority Medium
Opportunity Improve equipment supportability
TechnicalIssues
Cost
Previous Work AEM/S on USS Radford and LPD-17
Return onInvestment
Low
Advanced Enclosed Mast Systemfor LPD 17 Class Ships
page 110
O4COMPOSITESMARINE COMPOSITES
Piping
Priority High
Opportunity Eliminate corrosion related maintenance:reduce weight & vibration
TechnicalIssues
Cost and fire
Previous Work Numerous offshore installations and Navyprototypes waiting congressional plus-up
Return onInvestment
High
Ameron’s Bondstrand® 2000USN MIL-P-24608 Pipe Assembly Weighs 3.6 pounds
Compared to 6.8 pounds for CuNi
FIBERBOND® Pipe Shown to Withstand2000ºF Fires [EDO Specialty Plastics]
page 111
O4COMPOSITESMARINE COMPOSITES
Plenums
Priority High
Opportunity Eliminate severe corrosion and associatedmaintenance
TechnicalIssues
Cost and fire
Previous Work Plastic turning vanes have been fielded on alimited basis
Return onInvestment
HighProposed FFG Composite Plenum for1180 CFM Nat Supply Aux Mchry Rm #3, Helo Hgr #2, 1-278-2-Q
page 112
O4COMPOSITESMARINE COMPOSITES
Propellers
Priority Low
Opportunity Potential to make propellers quieter
TechnicalIssues
Strength and cost
Previous Work Existing systems for large yachts and R&Dwork on underwater propulsors
Return onInvestment
Low
The Contur® Propeller withExchangeable Composite Blades
Offered by AIR Fertigung-Technologie GmbH, Germany
page 113
O4COMPOSITESMARINE COMPOSITES
Propulsion Shafting
Priority Medium
Opportunity Reduce vibration, weight and corrosionmaintenance
TechnicalIssues
Interface to metal couplings and cost
Previous Work Commercially available for high speed craft,NSWC Annapolis prototype work on AOE &subs
Return onInvestment
Medium
33 inch Diameter Filament WoundSection of Propulsion Shafting
Developed by DTRC, Annapolis forTesting to Meet AOE-ClassPerformance Requirements
[George Wilhelmi]
page 114
O4COMPOSITESMARINE COMPOSITES
Pump Internals
Priority High
Opportunity Increase mean time between failure andreduce time to repair
TechnicalIssues
Standardization of U.S. Navy pumppopulation
Previous Work ERM-7 has fielded composite pumpinternals on 19 ships
Return onInvestment
High
Navy Shock-Qualified CompositePump Internals Built by Flowserve
page 115
O4COMPOSITESMARINE COMPOSITES
Pumps
Priority High
Opportunity Reduce corrosion, much quicker to repairand quieter
TechnicalIssues
Cost and standardization of U.S. Navy pumppopulation
Previous Work ERM-7 has funded production of 1 sizepump, ManTech effort pending
Return onInvestment
High
Navy Shock-Qualified CompositePump Built by Flowserve and Installed
as Part of the Navy’sSMARTSHIP Program
page 116
O4COMPOSITESMARINE COMPOSITES
Saltwater Piping
Priority High
Opportunity Potential to reduce corrosion, fouling andvibration problems
TechnicalIssues
Fire & certification
Previous Work Many offshore installations and proposedU.S. Navy use pending congressional plus-up
Return onInvestment
High Composite Pipe Installedin Severe Saltwater ShipEnvironment (Ameron®)
page 117
O4COMPOSITESMARINE COMPOSITES
Seachest Strainers
Priority High
Opportunity Reduce corrosion and integrate antifoulingagent
TechnicalIssues
Integrate effective, environmentally-friendlyantifouling
Previous Work PMS 400F funding pilot program
Return onInvestment
High
Fouled SeachestStrainer (top) Cutout
(middle) andPrototype
Composite Strainer(bottom)
page 118
O4COMPOSITESMARINE COMPOSITES
Topside Superstructure
Priority Medium
Opportunity Potential for in-situ repair of chronicaluminum deckhouse corrosion areas
TechnicalIssues
Fire and bond to aluminum
Previous Work Numerous prototype systems developedincluding MARITECH, Helo Hanger andManTech projects
Return onInvestment
Low
MARITECH CompositeSuperstructure Project Built by
Structural Composites and Ingallsusing Adhesive Technology
page 119
O4COMPOSITESMARINE COMPOSITES
Valves
Priority High
Opportunity Potential to extend service life, andsignificantly reduce maintenance andadverse mission impacts of corrosion-pronemetal components by using compositematerials. Potential to eliminate hydroblastcleaning of CHT system valves
TechnicalIssues
Shock qualification and fire
Previous Work Composite valves have passed shock test(NAVSEA drwg 803-6983491) and installedon 6 ships. The Capital Investment forLabor program plans on a major carrier CHTsystem installation.
Return onInvestment
High
Composite Ball-ValveFamily Developed by
NSWCCD
page 120
O4COMPOSITESMARINE COMPOSITES
Vent Screens
Priority High
Opportunity Eliminate corrosion related maintenance andimprove operability
TechnicalIssues
Fire
Previous Work ERM-7 has fielded composite vent screenson 13 ships. NAVSEA drwg 803-6983500,Vent Screen, GRP Installation and Detailswill lead to MODAR screens in the supplysystem by the end of FY 03.
Return onInvestment
High
Example of VentScreen Fielded by
ERM-7
page 121
O4COMPOSITESMARINE COMPOSITES
Ventilation Ducting
Priority High
Opportunity Eliminate corrosion related maintenance;improve ship air quality and improve shipavailability
TechnicalIssues
Cost
Previous Work NSWCCD and ManTech have fieldedprototype systems
Return onInvestment
High
Prototype Composite VentilationDuct System Built by Boeing and
Structural Composites Installed on theUSS Samuel B. Roberts, FFG-58
page 122
O4COMPOSITESMARINE COMPOSITESNaval Composites Application Summary
• U.S. Navy Focused on Vacuum Assisted Resin TransferMolding (VARTM) and other Closed Mold Methods toEnsure Environmentally-Compliant, High-Quality Parts
• Major Drivers Towards the use of Composites on NavyShips are: Corrosion Avoidance, Reduced Weight; Sensor Integration; and Increased Stealth
• Fire Performance Remains the Largest Obstacle, Although Cost is Increasingly Being Considered
• Procurement Process and Retrofit Opportunities RemainDifficult to Navigate - Supplier Partnerships Necessary
page 123
O4COMPOSITESMARINE COMPOSITES
Performance of Marine CompositeStructures In-Service (4:30 - 5:00)
• Inspection Methods
• Sources & Types of Damage
• Repair Methods
• Future Developments• Manufacturing• Shock Mitigation
Session 4
page 124
O4COMPOSITESMARINE COMPOSITESInspection of Marine Composite Structures
• Visual Inspection is Still the Primary Method forDetecting Failures
• Failures in Cored Construction can be Detectedby “Tap Testing” or “Weight Gain”
• Minor Surface Damage may not Necessarily Affect Performance of the Platform
• Boat Units Should Develop an Inspection Regimen that is Platform Specific
page 125
O4COMPOSITESMARINE COMPOSITES
Examples of Gel Coat Cracking
Cracks influencedby surroundinglaminate
Radial CrackPattern
Parallel CrackPattern
Crack caused byhole or other stressconcentration
Typical Failures Found in Composite BoatsMost failures are from:
• Inadequate design
• Improper selection of materials
• Poor workmanship
Most common failures:
• Gel coat cracking
• Core separation from skin insandwich construction
• Blisters on underwater portionof hull
page 126
O4COMPOSITESMARINE COMPOSITES
DeckLoading
HullTorsion
HullTorsion
PeelStress
PeelStress
SideShell
Loading
HullBendingMoment
Hull-to-Deck Joint Stresses
page 127
O4COMPOSITESMARINE COMPOSITES
CompartmentFlooding
Loads
LoadingTransferredFrom Deck
Hydrostatic, Slamming and
Blocking Loads
PeelStress
Shear Stresses
StressConcentrations
Bulkhead Attachment Stresses
page 128
O4COMPOSITESMARINE COMPOSITES
HullBendingMoment
StressConcentrations
Stiffener Stresses
page 129
O4COMPOSITESMARINE COMPOSITES
FlexuralLoading
Tension andCompression
StressConcentrations
Shear Stresses
Sandwich-to-Solid Transition Stresses
page 130
O4COMPOSITESMARINE COMPOSITES
Tension and
Compression
Stress
Concentrations
Secondary Bonded Joint Stress
page 131
O4COMPOSITESMARINE COMPOSITES
Types of Failures in Bolted Joints
page 132
O4COMPOSITESMARINE COMPOSITES
•Bulkhead
•Deck
•Tape
•Adhesive
Adhesively Bonded Joint Stress
page 133
O4COMPOSITESMARINE COMPOSITESDeck Hardware Stresses
page 134
O4COMPOSITESMARINE COMPOSITES
WaterIntrusion
OverturningMoment
HydrostaticForce
ShearStress
StressConcentrations
Through-Hull Penetration Stress
page 135
O4COMPOSITESMARINE COMPOSITESChine & Spray Strake Stress
page 136
O4COMPOSITESMARINE COMPOSITESNondestructive Evaluation of Composite Ship Structures
Bar-Cohen, Nondestructive Evaluation (NDE) of Fiberglass Marine Structures, US Coast Guard report CG-D-02-91
0% 10% 20% 30% 40% 50% 60% 70%
Tap Testing
Ultrasonics
FokkerBondtester
Bondascope 2100
MIA 2500
Radiography
Thermography
Dielectric Constant
Effectiveness of Various Potential NDE Methods
Defects Considered:• Impact Damage• Voids• Dry Fibers• Through Cracks• Delamination• Uncured Resin• Excessive Core Filling• Gap Between Stiffener and Web• Sheared Stiffener
page 137
O4COMPOSITESMARINE COMPOSITES
• Damage from In-Service Loads• In-Water Operational Loads• Trailering, Hauling and Blocking Loads
• Fatigue Loads• Wave Encounter• Machinery Induced
• Impact with Foreign Objects
• Fire
• Environmental Effects• Water Absorption• UV and Temperature Degradation
Sources of Marine Composite Damage
page 138
O4COMPOSITESMARINE COMPOSITESStatic vs. Dynamic Damage Tolerance
page 139
O4COMPOSITESMARINE COMPOSITESImpact Scenarios & Structural Evaluation
Schematic Diagram of Dynamic PanelTesting Pressure Table [Reichard]
Instron’s Dynatup®8100 Series DropWeight Impact TestSystem Can HandleImpact Energies upto 20,500 ft-lbs andImpact Velocities upto 22 ft/s
Wave Impact(left) and ShipImpact (right)
page 140
O4COMPOSITESMARINE COMPOSITES
Fire Performance Issues
Flame SpreadThe rate that flame travels along the surface
Fire ResistanceThe ability of a boundary to contain a fire
Time-to-IgnitionTime required before a combustible material ignites
Heat Release RateThe heat release of a material is measures theamount of fuel that a combustible material contributes to a fire
Structural IntegrityHull, deck and bulkheads must support design loadsduring and after a fire
Composite Panels being Tested to ISO 9705 as per the International Maritime Organization
page 141
O4COMPOSITESMARINE COMPOSITESIntermediate-Scale Fire Testing
Lighting of Burner to Start ModifiedISO 9705 Room Corner Test
at VTEC Laboratories
Schematic of ISO 9705 Room CornerTest to Determine Flame Spread and
Smoke Generation
page 142
O4COMPOSITESMARINE COMPOSITES
Full-Scale Fire Testing
Test Arrangement for Burn ThroughResistance of 10 x 10 - foot Panel
Full-Scale Fire Test forHelicopter Hanger Project
with Fire Protection Around Doorfor Fire Test Only
page 143
O4COMPOSITESMARINE COMPOSITES
Blistering and Water Absorption
Layer A = Paint or gel coatLayer B = interlayerLayer C = laminate
Measured/Predicted Material“Knockdown” Strength basedon Moisture Uptake (Springer)
page 144
O4COMPOSITESMARINE COMPOSITES
Elevated In-Service Temperature
Surface Temperaturesto 80 degrees C
page 145
O4COMPOSITESMARINE COMPOSITESDamage Assessment
Damages can be found either by visual inspection, probing, orhammer sounding of the structure. Damage can be found fromindicators such as the following:
• Cracked or chipped paint of abrasion of the surface.• Distortion of a structure or support member.• Unusual build-up or presence of moisture, oil, or rust.• Structure that appears blistered or bubbled and feels soft
to the touch.• Surface and penetrating cracks, open fractures, and
exposed fibers.• Gouges.• Debonding of joints.
page 146
O4COMPOSITESMARINE COMPOSITESDamage Repair
Typical Composite MaterialRepair Techniques
Laminate Peeler usedto Repair SevereBlister Damage
page 147
O4COMPOSITESMARINE COMPOSITES
• In-plane properties are always degraded for repaired compositestructures
• 20:1 scarf repairs are more effective than repairs made involvingless area
• Special skills, materials and environmental controls required foreffective repairs
• Aerospace level repair methods not envisioned for marine structures
• Single-skin, E-glass laminates are easier to repair than carbonfiber and sandwich constructions
Marine Composite Repair Summary
page 148
O4COMPOSITESMARINE COMPOSITESFuture Manufacturing Methods
Advanced Interlaminar Infusion
• Thicker Laminates
• Center Out Process Advantage
• Embedded LO/EMI
• Damping Layers– Noise– Vibration– Shock
• Damage Tolerance
page 149
O4COMPOSITESMARINE COMPOSITESFuture Manufacturing Methods
Infusion Challenges
• Tool Loading
• Resin Technology– Cure on Demand (COD)
• Inclusion of Framing– Preforms
• Preform Laminates
• Kit Cut Laminates
• Bag System
page 150
O4COMPOSITESMARINE COMPOSITESFuture Manufacturing Methods
• Infusion Bag is Sprayed in Place
• Inclusion of Preform Frames and Resin Feeder System
• Bag Becomes Interior Surface
Spray-Bag Process
• ADVANTAGES– Reduced Cost– Elimination of Interior Gel Coat– Process Risk Reduction– Reduction in Expendables– Ship Applications Would use Bag as Fire Protection System
page 151
O4COMPOSITESMARINE COMPOSITESComposite Structure for Shock Mitigation
Schematic of CoupledHydroelastic Impact Modelwith Variable Impact Velocityby Vorus et al
Wave Impact
Hull-to-DeckConnection
Personnel Reaction Force
page 152
O4COMPOSITESMARINE COMPOSITESSummary and Conclusions
• Composite structures can be highly “engineered”
• Structural integrity is dependent upon worker skill
• The US continues to lead the world in the developmentof marine composite fabrication technologies
• Emerging manufacturing technologies will permit “environmentally compliant” fabrication of platforms
• Future maritime platforms can improve shock mitigationand durability using a combination of compositestructural design and process development
page 153
O4COMPOSITESMARINE COMPOSITES
Acknowledgments
This Composites Workshop was gearedspecifically to the needs of the US MarineManufacturer. The Workshop wasdeveloped by Eric Greene Associates,Inc. with support from the US Navy andthe American Composites ManufacturersAssociation (ACMA). Special thanks goto Mary Richman, CCT of the ACMA.