AIRCRAFT COMPOSITE STRUCTURE REPAIR
Manufacturing Process
Introduction to Composite Materials 1 ATA 51 - Aircraft Composite Repair
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Continuous void free resin matrix
Maintain accurate fiber architecture
Reliable and repeatable process
Specific resin content
Aerospace Manufacturing
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Manufacturing process
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Manufacturing Technique
Hand lay up
Automated process
Filament Winding
Liquid Resin infusion
Thermoplastic
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Manufacturing process
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• Hand lay up
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Manufacturing process
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Manufacturing process
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Wet Hand Lay Up – Vaccum Bag
Dry fibers are saturated with mixed resin until all are soaked. Bagging materials are placed on the fabricated item and sealed it to vacuum the air out. The atmospheric pressure in pushed on the part during curing.
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Wet Hand Lay Up – Vaccum Bag
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Wet Hand Lay Up – Reusable Bag
Silicone based material
Instead of using bagging materials, a mix part silicone materials are poured on the mold and cured following the mold’s shape. Once the fabricated items are soaked with the resin, the silicone bag is placed on the part and let to cure.
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Dry Layup – PrePreg Material
Autoclave curing, high temperature with 4~6 bar pressure
Oven curing, high temperature but with 1 bar atmospheric pressure. Known as out of autoclave curing (OOA)
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Dry Layup – PrePreg Material
Thermocouple
Vacuum Bag Film Breather/ Bleeder Release Film (with or without perforations) Peel ply Laminate Mold Release
Autoclave/ Oven hose Quick Disconnect Vac Valve
Pressure sensitive tape
CTFE connection fitting
Masterbar composite Support structure
Vacuum bag sealant tape
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Dry Layup – Heat Blanket System
Used only during aircraft composite repair. Localized heat. Ease of mobility. High temperature curing with 22 inHg or 1bar of vacuum.
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Dry Layup – Heat Blanket System
Thermocouples Sealant tape
Flash tape or polyester disc
Core ply adhesive
Peel ply
Release film perforated or teflon coated fiberglass porous
Silicone rubber heat blanket
Breather/ bleeder
Nylon Bagging film
Release film non perforated or teflon
coated fiberglass/ non-porous
Caul plate (optional)
Fiberglass bleeder cloth
Repair plies
Vacuum hose/ sniffer assembly
Vacuum hose/
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Fibre is chopped in a hand-held gun and fed into a spray of catalysed resin directed at the mould. The deposited materials are left to cure under standard atmospheric conditions.
Chopped Spray
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Chopped Spray
Resin
Catalyst
Mixer control
Chopper gun
Swivel arm
Resin outlet
Fiber cutter
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Chopped Spray
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Filament Winding
Continuous and Finite fabricated
part.
Suitable to make circular or oval
shapes
Pultrusion
Continuous and infinite fabricated part with more
cross section pattern available.
Fiber alignment along pulling direction
Instant curing
Pull-winding
Combination of filament winding and pultrusion
Fiber alignment are braided type orientation
Instant curing
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Manufacturing process
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Advantages
Fast & economical lay out
Controlled resin content
Low material cost and no secondary process
Fibers can be laid to match loading direction
Disadvantages
Limited to convex shaped
Cannot cannot be laid along the length of the part
Mandrel cost is high depend on size and shape
Internal surface is unmolded- aesthetic
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Manufacturing process
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Fibre tows are passed through a resin bath before being wound onto a mandrel in a variety of orientations, controlled by the fibre feeding mechanism, and rate of rotation of the mandrel.
Filament Winding
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Filament Winding
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• Winding Patterns Manufacturing Process
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Filament Winding
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Fibres are pulled from a creel through a resin bath and then on through a heated die. The die completes the impregnation of the fibre, controls the resin content and cures the material into its final shape as it passes through the die
Pultrusion
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Manufacturing Process Pultrusion
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Similar to pultrusion, the fibres are pulled from a creel through a resin bath and then on through a braided arrangement heated die. The die completes the impregnation of the fibre, controls the resin content and cures the material into its circular shape as it passes through the die
Pull Winding
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Vacuum Assisted Resin Transfer Molding
•Draw resin to mold cavity by vacuuming the air to vacuum pot
•A380 Vertical tail plain component, A330-200 Fin box rib
Resin Transfer Molding
•Resin is injected to closed mold at the same time vacuum is drawn out
•Fittings, rib, aileron spar
Resin Film infusion
•Layer of precatalysed resin film and dry reinforcement applied on mold and cured at high temperature. Resin film will melt and infused to the dry fabric
•A380 Aft pressure bulkhead, A380 wing lower access panels
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Manufacturing process
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Manufacturing process
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Fabrics are laid up as a dry stack of materials in between male and female mold. Resin is injected to impregnate the fabric between 2 to 6 bars.
Resin Transfer Molding
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Resin Transfer Molding
Pump controller
Catalyst container
Acetone container
Resin mixture outlet Resin inlet
Ratio pump
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Fabrics are laid up as a dry stack of materials and covered by vacuum bag. The whole dry stack is then vacuum bagged, and once bag leaks have been eliminated, resin is allowed to flow into the laminate through the pulling of vacuum
Vacuum infusion/ Resin Infusion
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Fabrics are laid up as a dry stack of materials and covered by vacuum bag. The whole dry stack is then vacuum bagged, and once bag leaks have been eliminated, resin is allowed to flow into the laminate through the pulling of vacuum. A low viscosity resin is required in order to run this fabrication technique to eliminate wash out effect.
Vacuum infusion/ Resin Infusion
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Resin Film Infusion
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Dry fabrics are laid up interleaved with layers of semi-solid resin film supplied on a release paper. The lay-up is vacuum bagged to remove air through the dry fabrics, and then heated to allow the resin to first melt and flow into the air-free fabrics, and then after a certain time, to cure.
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Compression Molding
A preform substance is placed in a hydraulic press with heated platens. The preforms can be in the form of Dough Molding Compound (DMC), Sheet molding compound (SMC) or even pre-impregnated materials. The heated platens shorten the curing thus increase the cycle time of a product.
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Compression Molding
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Automated Tape Laying
Flat surface,
Automated Fiber Placement
Curvature
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Manufacturing process
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• Automated fiber Placement
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AIRCRAFT COMPOSITE STRUCTURE REPAIR
ATL machinery lays fibre down in the form of pre-preg unidirectional tape or continuous strips of fabric, rather than single tows. Usually for a big and long flat panel which a high consistency and accuracy are needed. The uncured part is still cured in a temperature assisted environment such as autoclave
Manufacturing Process Automated Tape Laying
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Automated Tape Laying
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AFP was developed as a solution automating lay up of complex 3-D shapes with concave and other asymmetrical configurations. It combines the motion characteristics of a filament winder and the fibre lay-up attributes of a tape laying machine therefore it can fabricate any complex structures. Heat assisted curing is still required once the placement process has finished.
Manufacturing Process Automated Fiber Placement
AIRCRAFT COMPOSITE STRUCTURE REPAIR
Manufacturing Process Automated Fiber Placement
Fixed mold with contour shape. Rotating mold and movable head Special placement for openings.
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Manufacturing method 1 3 2
1 3 2
1 3 2
Laminating and curing of skins and spars
Adhesive film
Honeycomb core Fit to size
Inner and outer skins Layers of Fabric or Tape
Co-curing Process
Co-bonding Process
Secondary bonding multiphase process
Inner skin 1 uncured Outer skin 2 uncured
Both skins 1 and 2 are cured together with honeycomb core 3, effectively created a single part
Inner skin 1 cured Outer skin 2 uncured
Components 1 and 3 bonded during cure cycle of component 2
Individual skins 1. 2 and spars are cured
In a second operation, honeycomb core 3 and individuals skins 1,2 and
devices are bonded together Note: 1 & 2 are cured by using autoclave at 7 bar
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Manufacturing methods
1
2
1
2
1
2
Adhesive (optional)
Adhesive
Co-curing Process
Co-bonding Process
Secondary bonding multiphase process
Component 1 uncured Component 2 uncured
Components cure together, effectively creating a single part
Component 1 cured Component 2 uncured
Component 1 bonded during cure cycle of component 2
Component 1 cured Component 2 cured
Components bonded together with separate bonding
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Manufacturing methods
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Manufacturing methods
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Manufacturing methods