Technical Interchange Meeting Combat Tempered Composite Repair Jonathan Garhart Tech Lead Advanced Structures Norfolk VA June 1415 2016 This research was partially funded by the Government under Agreement No W911W61220005 ID: 545078
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DoD Advanced Composite Maintainer’s Technical Interchange Meeting
Combat Tempered Composite Repair
Jonathan Garhart
Tech Lead Advanced Structures
Norfolk, VAJune 14-15, 2016
This research was partially funded by the Government under Agreement No. W911W6-12-2-0005. 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. GovernmentDistribution Statement A - Approved for Public Release - Distribution UnlimitedSlide2
Future Composite Airframe
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The next generation aircraft will require next generation repairsSlide3
Field Repair Challenges
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Large integrated structures require in situ repair
Primary structure repairs require high strength laminates
Wet lay up not amendable to process controlLow temp curing laminating resins have limited ETW properties
In situ curing difficult to controlLack of freezer storage restricts use of prepreg materialsPrecured patches only work for limited locationsComplex and contoured structures require cure in place or toolingHeating airframe to 350 F may be impractical or imprudentHow can depot style repairs be transferred to the operational levelSlide4
Next Generation Materials
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Benzoxazine Prepreg – Henkel IM7 / BZ9704.2 196 gsm PW*
Room Temperature storage for 12 months
Out of Autoclave processingETW allowable rival 8552Low outgassing – low void content
Low shrinkage – stable geometryLow Temp Curing Paste Adhesive - Hysol EA9359Long shelf lifeHigh strength – high strain adhesiveRoom / Low Temperature cure* Henkel Product discontinued –Viable replacements being evaluatedNew materials enable repairs in challenging environmentsSlide5
Conformal In Situ Repair
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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 laminatesSlide6
Demonstrated Capability
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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 worldSlide7
Discussion – Wrap up
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Questions?