Damage and Repair of Aerospace Composite Materials reports the latest developments on the detection and repair of composite structures in the aerospace industry, with an outline of general damage inspection and repair processes. This includes porosity inspection, damage detection using acoustic ultrasonic and radio frequency methods, and the automated defect-inspection system integrated in the production line by utilizing laser sensors and cameras. Fiber reinforced composites have been increasingly used for large-scale structural applications in the aerospace industry due to their ability of reducing airframe weight, improving fuel economy, and lowering overall operating costs. Conversely, this new trend has brought up tremendous challenges on the repair side. Like other structural materials, composites can contain or develop various defects and damages, which can occur during the manufacturing stage, and throughout the service life of the aircraft. If they go unobserved or untreated on time, the results can be catastrophic. Damage and Repair of Aerospace Composite Materials also offers insights into the design of a bonded repair technique for multilayer laminate composite panels, the analysis on the performance of bolted repair vs. bonded repair, and how to economically repair holes, and the use the 3D-printing to repair gaps and steps in large composite panels.
Author(s): Charles Lu
Publisher: SAE International
Year: 2019
Language: English
Pages: 145
City: Warrendale
Cover
OVERALL COMPOSITE USAGE
CHAPTER 1 Composite Structure Utilization-Commercial Airplanes
Introduction
Airplane Structure
Honeycomb Structure
Core Materials
Foam Core
Fluted Core
Syntactic Core
Nomex Core
New Generation Aramid Core
Carbon/Carbon Core
Laminate Materials
A-Stage Materials
Carbon Fiber Reinforcement
Kevlar Fiber Reinforcement
Glass Fiber Reinforcement
B Stage Materials
Carbon/Epoxy Prepreg
Kevlar/Epoxy Prepreg
Fiberglass/Epoxy Prepreg
Adhesives
Laminate Structure
Design Considerations
Manufacturing Considerations
Maintenance Considerations
In-Service Inspection
In-service Repairs
Nondestructive Inspection of Composite Structure
Tap Testing
Automated Tap Test Devices
Ultrasonics
Generation of Two and Three Dimensional Images to Produce Wide Area Inspection Methods
A-Scan Mode
Wide Area Inspections Aided by C-Scan Mode
Mechanics of C-Scan System
Low Frequency Bond Testing
Mechanical Impedance Analysis
Thermography
Conclusion
Contact Information
References
DAMAGE DETECTION OF COMPOSITE STRUCTURES
CHAPTER 2 Porosity Assessment in Large Composite Components: Realization and Challenges
Introduction
Typical Defects in Composite Structures
Ultrasonic Inspection Techniques
Semi-Automated Inspection System
Automated Inspection System
Defects Signature - Pulse Echo
Defects Signature - Through Transmission
Porosity Assessment - Pulse Echo
Porosity Curves Development
Void Content Assessment
Thickness Dependency
Averaging
Frequency Dependency
Morphology Dependency
Laminar Indications Area
Pulse Echo Porosity Assessment Limitation
Attenuation vs Void Content: Porosity Curves
Transfer Values
Arithmetic for Transfer Value
Transfer Value - Material Composition
Transfer Value - Surface Coating
Transfer Value - Interface
Porosity Assessment - Through Transmission
Porosity Assessment - Through Transmission Results
Summary/Conclusions
References
CHAPTER 3 Detecting Damage and Damage Location on Large Composite Parts Using RFID Technology
Introduction
Presentation of the Solution
Acoustic Ultrasonic
Technology/Application Discriminators
Technology Inhibitors
Accelerometers
Technology/Application Discriminators
Technology Inhibitors
3. Radio Frequency (RF) Sensors (Shock Vibration)
Technology/Application Discriminators
Technology Inhibitors
Technology Tests
Sensor Positioning/Location
Acoustic Ultrasonic
Accelerometers
Radio Frequency (RF) Sensors (Shock Vibration)
Test Results
Acoustic Ultrasonic
Accelerometers
Radio Frequency (RF) Sensors (Shock Vibration)
Conclusions and Recommendations
Acknowledgements
References
CHAPTER 4 Discrimination between Damaging and Non-Damaging Impact Events on Composite Structure using SHM Sensor Signal Analysis
Introduction
Experimental Approach
Experimental Results
Impact Damage Classification Based on Sensor Signal Characterisitcs
Summary/Conclusions
Contact Information
Acknowledgments
References
CHAPTER 5 AFP Automated Inspection System Performance and Expectations
Introduction
Inspection Process Overview
Ply Boundary Inspection
Overlap/Gap Inspection
Inspection User Interface
Inspected Part Model
Overlap/Gap Interface
Ply Boundary Inspection
Fully-Automatic
Semi-Automatic
Pointing to Defects
Inspection Time
Ply Boundary
Overlap and Gap
Inspection Data
Accuracy
Ply Report
Data Volume
Data Value and Utility
Resource Burden
Hardware Cost
Summary/Conclusions
Contact Information
Definitions/Abbreviations
References
DAMAGE REPAIR OF COMPOSITE STRUCTURES
CHAPTER 6 Design and Evaluation of Novel Composite Aircraft Repairs
Introduction
Typical Metallic Doubler Installation
Typical Composite Doubler Installation
Assessment of DC-10 Composite Doubler Design
Fatigue Tests: Flawed Specimens
Fatigue Tests: Baseline (Unflawed) Specimens
Effects of Impact
Finite Element Analysis
Damage Tolerance
Repair Design Validation
Nondestructive Inspection (NDI)
Pitch/Catch Impulse Testing
Pilot Program
Conclusion
Contact Information
References
CHAPTER 7 Design and Analysis of Aeronautical Repair: Fastened × Bonded
Introduction
Finite Element Model
Damaged Plate
Bonded Repair
Computational Toll (SAJ)
Fastened Repair
Results
Summary and Conclusions
Contact Information
Acknowledgments
References
CHAPTER 8 Economical Repair of Damaged and Discrepant Holes in Metals and Composites
Introduction
Expanded Bushing Methods
Composite or Composite/Metal Joint Repair
Panel Repair
Summary
References
CHAPTER 9 New Cutting Tools for Repairs of Composites
1. Introduction
1.1 Milling Thin CFRP Layers
1.2 Scarfing of CFRP: The Right Strategy
1.3 The Right Tools Scarfing CFRP
2. Experimental Testing and Results
3. Conclusions
References
CHAPTER 10 End-Effector for Automatic Shimming of Composites
Introduction
Description of Concept
Shimming End-Effector
Extrusion Head
Hot-End
Bed Heating System
Control System
Validation of the Concept: Results
Conclusions
Contact Information
Acknowledgments
Definitions/Abbreviations
References
