1. DoD Advanced Composite Maintainer’s Technical Interchange Meeting
Combat Tempered Composite Repair
Norfolk, VA
June 14-15, 2016
Jonathan Garhart
Tech Lead Advanced Structures
This research was partially funded by the Government under Agreement No. W911W The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation thereon.
The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Aviation Applied Technology Directorate or the U.S. Government
Distribution Statement A - Approved for Public Release - Distribution Unlimited

2. Future Composite Airframe
The next generation aircraft will require next generation repairs

3. Field Repair Challenges
Large integrated structures require in situ repair
Primary structure repairs require high strength laminates
Wet lay up not amendable to process control
Low temp curing laminating resins have limited ETW properties
In situ curing difficult to control
Lack of freezer storage restricts use of prepreg materials
Precured patches only work for limited locations
Complex and contoured structures require cure in place or tooling
Heating airframe to 350 F may be impractical or imprudent
How can depot style repairs be transferred to the operational level

4. Next Generation Materials
Benzoxazine Prepreg – Henkel IM7 / BZ gsm PW*
Room Temperature storage for 12 months
Out of Autoclave processing
ETW allowable rival 8552
Low outgassing – low void content
Low shrinkage – stable geometry
Low Temp Curing Paste Adhesive - Hysol EA9359
Long shelf life
High strength – high strain adhesive
Room / Low Temperature cure
* Henkel Product discontinued –Viable replacements being evaluated
New materials enable repairs in challenging environments

5. Conformal In Situ Repair
1. Lay up Benzoxazine repair plies on contoured part with separator release film on both sides.
2. Wet layup IM7/EA956 8HS scaffold plies over repair, vacuum bag and low temp cure.
3. Envelop bag repair and cured scaffold and cure at 350 F off the structure.
4. Bond cured repair laminate to component using vacuum bag pressure and Hysol EA9359 paste adhesive.
Simple process - quality laminates

6. Demonstrated Capability
Significant Benefits
Room Temperature Storage
High Strength, Low Weight Repair
All Contoured Surfaces
No Heating of Airframe Structure
Patent Submitted to USPO
Validated through Full Scale Test
Local Repair of Buckled Skin Plies
Repairs executed in AATD structures lab
Passed Limit / Ultimate / Fatigue
Repair intact after article tested to failure
Works in the real world

7. Discussion – Wrap up
Questions?