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Process Fragility in the Manufacture of Kevlar Wing Root Panels
Location of wing root panel
2m
James Curran
• Complex curvature• Kevlar• Sandwich panel• Geometrical tolerances• Foiling cure• Increased production rate
• RED panels further down production line• Unconventional• No destructive analysis• Production item (no interference, limited changes)
Increasing scrap rate NDT (ultrasonic, X-ray, geometry)
Plan to double production rate
Roll-out in Toulouse
1
2
3
4
1*
1*
NDT Failures
Simplified cross-section
14 plies
Steel ToolPlies 1-7
Honeycomb
AdhesivePly 8
Vac bag
Key operations half-way through build
Problems:• Bridging• Core (positioning & moisture content)• Volatiles• Filler material• Poor consolidation
Areas signalled for more intensive working
Steel ToolPlies 1-7
Honeycomb
Adhesive
Vac bag
Bleed pack
Bleed pack introduced for improved consolidation
12 3 (4)
Adhesive lay-up modified
1
2
3
4
1*
1*
Steel ToolPlies 1-7
Honeycomb
Vac bag
Plies 8-14Intensifier
Inadequate moisture management
1
2
3
4
1*
1*
Problems with honeycomb trim under floating intensifier:
2: Resin bleed 3: Poor consolidation
Core filler
Kevlar prepreg volatile content
19.4
19.6
19.8
20.0
20.2
15:00 15:30 16:00 16:30 17:00 17:30 18:00
Time
Mas
s (g
)
1
2
3
4
1*
1*
• New adhesive lay-up• Use of a bleed pack for all consolidation operations• Core moisture control• Core trimming• Core filler control• Kevlar moisture management
• Perforated adhesive• Self-adhesive foil / elimination of separate foiling cure• New tooling
Solutions: