Composite Manufacturing

Group 15 Eglin AFBBrandon Bair - John Brewer - Darnell Brown - Rob Contes

Sponsor: Jeff Wagener - Lt Joe Czabarnek, AFRL

Faculty Advisors: Dr. Chiang Shih (ME) - Dr. Richard Liang (IE)

Introduction

• Scope

• AFRL Fuselage Specifications

• Project Specifications

• Research

• Selection

• Original Design

• Design Development

• Construction

• Testing

• Hiring

• Conclusions

• Recommendations

• Summary

• Questions

Scope

The scope of this project was to redesign and test the fuselage of the Bullwinkle Micro Aerial Vehicle and “hire” a manufacturer to produce it.

AFRL Fuselage

• Length - 15.75”

• Width - 2.25”

• Height - 2.25’’

• Construction

• 2 part Design

• Male mold

• Pre-impregnated carbon fiber

• Assembled with nylon screws

• Motor Mount – Sheet aluminum

Project Specifications

• Same size and shape

• Survive a 30o impact at 20 m/s (45mph)

• Ensure that motor heat will not affect structure

• Manufacturing

• 30 units

• $300 per unit

• $20,000 for start-up

• 1 month start-up, 1 month production

Research

• Materials

• Resin

• Processing

• Curing

Research: Materials

• Glass Fiber

• Carbon Fiber

• Kevlar

Glass Fiber

• Pros

• Lightweight

• Inexpensive

• Cons

• Heavier than

other composites

Carbon Fiber

• Pros

• Light weight

• Very strong

• Durable

• Cons

• Very expensivematerialogical.com/wordpress/?cat=7

• Developed by DuPont in 1965

• Pros

• Thermal and electric insulator

• Absorbs energy

• Cons

• Breaks down in UV light

• Sublimes at 450oC

Kevlar

www.kevlar.com

Research: Resin

• Polyester• Inexpensive• Low order crosslinking

• Epoxy• Difficult to use• High order crosslinking

• Vinyl Ester• Compromise• Easy to use

Research: Bonding Processes

• Resin Transfer

• Contact Molding

• Vacuum Bag

Resin Transfer

• Process• Material held in a closed mold• Resin injected

• Pros• Smooth, even sides• Few voids

• Cons• Complex molds• Resin rich

http://www.rtmcomposites.com/whatrtm.htm2005

Contact Molding

• Also known as Hand Lay-Up Molding

• Material and resin are applied with a roller or brush by hand

• Pros

• Inexpensive

• Fast

• Cons

• Resin rich

• Labor

• Messy

Vacuum Bag Molding

Applies vacuum to hold a part securely to a mold

• Pros

• Product is smoother

• Controlled fiber and resin ratio

• Cons

• Time consuming

• Materials

Possible Curing Processes

• Autoclave – High temperature and pressure

• Oven – High temp

• Room temperature

Selection

• Material – Carbon Fiber

• Light weight

• Strong

• Standard in military MAV construction

• Resin – Vinyl Ester

• Forgiving catalyst ratio

• Strong and tough

• Process – Vacuum Infusion• Control resin ratio• Low voids

• Molds – Female, Plaster

Original Design

• Solid nose

• Main structure with cap

• Four parts

•10 Bonding strips

Design Development

• 4 main parts to 2 main parts

• Flat sheet

• 2 Bonding strips

• Cap

• Simpler

• Faster production

• More continuous structure and surface

Design Development

Construction: Molds• Wooden mold box

• Acrylic

• Wax

• Rapid prototyped

male mold form

• Industrial gypsum plaster

• Wax

Construction: Fuselage

• Wax • Poly Vinyl Alcohol (PVA)• Carbon Fiber• Peel Ply• Flow Media• Vacuum Bag

Bench Test• Run 1

• Full Power for 5 min

• No temperature change

• Run 2

• 50% for 7 min

• No temperature change

• Run 3

• 25% for 15 min

• No temperature change

Impact Testing

• Propelled with a pneumatic cannon• Impacted a target ramp at 30o • Speed measurement – Calibration board and semi-

high speed camera (120 fps)

Impact Results

• With motor

• Minimal damage

• Motor plate separation

• Retained structure

• With weight (3 lb total)

• Visible damage

• Motor plate separation

• Retained structure

Impact

Impact

Hiring

• ACMA

• Preliminary Contact

• Quote Request Package

• Detailed description

• Detailed drawings

• Prototype pictures

• Separate package

for motor plate

Conclusion

• Fuselage Manufacturer –TBD by AFRL

• At least 6 interested companies

• Timeline

• Production

• Motor Plate Manufacturer – Milco Water Jet

• Lot Price - $190 ($6.33 per unit)

• Timeline - 5 days

Recommendations

• Construct parts in house

• Low production numbers

• Quality control

• Variability

• Cost

• Research vacuum molding of polymers

• Quicker

• Less expensive

• Compliant parts

Summary

• Scope

• AFRL Fuselage Specifications

• Project Specifications

• Research

• Selection

• Original Design

• Design Development

• Construction

• Testing

• Hiring

• Conclusions

• Recommendations

• Summary

• Questions

Questions