1. Copyright 2017 Lockheed Martin Corporation
Advanced Integrated Composite Repair Sikorsky August 21, 2017
This work was sponsored by the Office of Naval Research, ONR, under contract number N C-0119; the views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the Office of Naval Research, the U.S. Navy or the U.S. government.
Distribution Statement A. Approved for public release; distribution unlimited
Copyright 2017 Lockheed Martin Corporation
This document does not contain export controlled technical data.

2. Acknowledgements George Bauer Jim Lua Kevin Dyer Errick Robles
Modeling and Structural Analysis
George Bauer
Behavior Modeling and Simulation
Jim Lua
Additive Manufacturing & Prototypes
Kevin Dyer
Structural Testing
Errick Robles
Design and Analysis
Mark Gurvich
Structural Analysis
Matt Gaspin

3. Advanced Integrated Composite Repair Sikorsky / Jonathan Garhart
Approach
Identify optimal materials, manufacturing and analytical technologies to enable the development of a lean composite repair cell based on 3D scanning, additive tooling and advanced laminate analysis.
Conduct coupon testing to develop laminate and bond properties for use in patch modeling and analysis.
Execute manufacturing trials to validate process in a sub-element scale representative setting.
Conduct element testing to demonstrate feasibility and structural integrity of patch fabrication and application methods.

4. Advanced Integrated Composite Repair Sikorsky / Jonathan Garhart
Elements of Novelty
Curing laminate off repair site allows for higher temperature cure of high performance material.
RT storage prepreg eliminates wet lay up without requiring freezer storage.
Latest scanning and 3D printing technology yield rapid and accurate tooling.
Benefits
High performance composites enable an expansion of the range of field repairs over current wet layup and fastened approaches.
Integrated field repair system expands shipboard maintenance options leading to increased aircraft availability.
Automated system reduces labor content and quality variability while improving process efficiency.

5. System Specification

6. System components selected and interactivity validated
System Specification
Material
Patz IM7/PMT-F31 Plain Weave
Room temp storage Benzoxazine
Scanning
Creaform: HandySCAN 3D™
High resolution hand held laser scanner
Additive Tooling Fabrication
Stratasys Fortus 400 MC
14” x 16”x 16” envelop FDM printer
Additive Tooling Materials
UltemTM 1010
215 C capable thermoplastic
Bond Surface Preparation
Surfx AtomFloTM 500
Plasma etching for bond surface prep
HandySCAN 3D™
Fortus 400 MC
Image courtesy of Stratasys
Surfx AtomfloTM 500
System components selected and interactivity validated

7. Repair Design & Analysis

8. Repair Process Flow Damage Site Scan Local Structural Criteria
Surface Data
Ansys
Abaqus
Space Claim
Model Generation
CAD/FE Model
Parametric Repair Model
Micromechanics Model -
Analytic Methods
Tooling Design
Optimized Repair Design
3D Print Data
Laminate Configuration
3D Printed Tool
Laminate Configuration
Fabricate Repair Laminate
Ply Data
Data
Repair Bonding
Surface Prep
Action / Product

9. Analytic model validated through coupon testing
Model Validation
Objective
Verify fidelity of fracture mechanics modeling predictions through the comparison analytical and empirical results.
Approach
Establish a specimen configuration that incorporates the features of a typical repair and which can be loaded to induce desire failure modes.
Conduct a series of analytical evaluations of various repair and material configurations to determine the relationship between performance and specific attributes.
Conduct physical testing of specific configurations to compare response and failure modes to predictions.
Analytic model validated through coupon testing

10. Specimen Configuration
Up To 9.25” Patch Region
2.25”
20.0”
3.0”
4 Point Bend Test Setup Induces Tension in Repair Patch/Sandwich Skin Interface
Representative repair and standardized test method

11. Manufacturing Demonstration

12. Demonstration validates process methods
Demonstration Plan
Objective
Validate all phases of the integrated repair process and interoperability of individual systems through the execution of a full scale repair trail.
Approach
Complete a skin laminate and core repair on a demonstration trial article with a structural configuration similar to a typical rotorcraft airframe component. The execution of the repair will utilize all aspects of the integrated system in a manner fully consistent with proposed deployed configuration.
Demonstration validates process methods

13. Demonstration Article
Section of Airfoil component
Carbon skins over aluminum honeycomb core
Representative composite structure provided by NavAir

14. Repair Preparation
Remove Primer & Prepare Site
Damaged Skin and Core Removed
Core Septum Installed to Seal Off Core
Core Filled and Faired Registration Holes Added
Standard methods and tools used to prepare repair site

15. Surface data acquisition and processing optimized
Article Scanning
HandySCAN 3D™ System
Scan Process
3 Resolution levels evaluated
Surface characteristics effect data capture
Data post processed in Space Claim
Engineered surface output as basis for tool design
Surface Data
Surface data acquisition and processing optimized

16. Tool and Repair Fabrication
Tool Modeling
3D Print Tool
Cure Patch
Tool design process established
Tooling construction optimized
Minimize build time & density
Maintain structural integrity
Laminate OoA processes methods established
Etch Surface
Bond Repair
Manufacturing Trial verifies process capability

17. Full Scale Test

18. Full Scale Repair Test Plan
Validate manufacturing repair and process technologies.
Establish baseline panel pristine static & fatigue strength
Exercise system-wide repair process:
Induce specific damage, optimize repair, design patch construction.
Execute repair and test: establish static and fatigue repair strength capabilities.
Program focus: aircraft sandwich skin structure.
Susceptible to damage, relatively large surface/exposure area.
Primarily carrying aircraft shear loading.
Engineer full scale test to:
Test repaired sandwich skin shear load capabilities.
Limit test fixture influence and unexpected failure modes.

19. Repair Test Plan P = ~60,000 lbf P Test Static/Fatigue Type 1 Static
Pristine 2
Fatigue 3
Repaired 4 5
Repaired w/Defect 6
Static/Fatigue Test Approach:
First test static article to determine ultimate failure load.
Measure panel shear strains. Scan article as needed.
Cycle fatigue test article at load of 2/3 ultimate strength.
If no failure or detectable growth is noticed, increase cyclic load by 10%

20. Summary - Conclusions System elements selected and integrated
Automated repair modeling approach established
Fracture mechanics model completed / validation proceeding
Manufacturing trial processes validated
Full scale tool complete
Material characterization testing in process
Full Scale test plan approved by NavAir