Front Cover

Morphing Wing Technologies: Large Commercial Aircraft and Civil Helicopters

Copyright

Dedication

Contents

Contributors

Editor-in-Chief Biographies

Biographies

Co-Editor Biographies

Contributor Biographies

Foreword 1

Foreword 2

Preface

Section 1: Introduction

Chapter 1: Historical Background and Current Scenario

1. Introduction

2. Components of a Wing Morphing Structural System

2.1. Structural Skeleton

2.2. Actuation Systems

2.3. Skin

2.3.1. Sensor system

2.4. Control System

2.5. Cabling

2.6. Assembly

3. The Main Challenges

3.1. Skins

3.2. Actuation Systems

3.3. Sensor Systems

4. Back to the Past

4.1. The Wright's Flyer

4.2. Plane and the Like for Aeroplanes

4.3. The Parker's Wing

4.3.1. An earlier vision

5. Modern Times

5.1. NASA Studies

5.2. DGLR Studies

5.3. The Mission Adaptive Wing

5.4. Further NASA Studies

6. Recent Activities—United States

6.1. Adaptive Wing Reborn: SMAs

6.2. The DARPA Smart Wing Program

6.3. The DARPA Morphing Aircraft Structures Program

7. Recent Activities—Europe

7.1. ADIF

7.2. Clean Sky

8. Current Scenario

8.1. Airbus—SARISTU (Smart Intelligent Aircraft Structures)

8.2. Boeing—Adaptive Wing

8.3. Flexsys and Gulfstream

8.3.1. Other relevant projects: Change and NOVEMOR

8.3.2. Future projects

9. The Tradition at the University of Napoli and CIRA

9.1. Adaptive Airfoil

9.2. The Hinge-Less Wing

9.3. Smartflap

9.4. SADE

9.5. Clean Sky—JTI-GRA—Low Noise

9.6. EU—SARISTU

9.7. The Adaptive Aileron

9.7.1. The AG2 project (JTI-GRA2) and the next future

10. Future Perspectives

10.1. Safe Design

10.2. Skins and Fillers

10.3. Direct actuation: The use of smart materials

10.4. Wireless, distributed sensing

10.5. Control system architecture

10.6. Cybernetics and Robotics

Acknowledgments

References

University of Napoli and CIRA International Awards

Chapter 2: Aircraft Morphing—An Industry Vision

1. Introduction

2. Current Aircraft Capabilities

2.1. Interest of Industry

2.2. Some Considerations About Industry Aerodynamic Design Process

2.3. Expected Performance Targets

2.4. Manufacturing: New Materials and Controlled Industrial Processes

2.5. Assembly and Quality: Automation and Integrated Parts

2.6. Maintenance: Assessed Steps and Personnel Training

2.7. Safety: Assessed Methods for Standard Architectures

3. Current and Expected Needs

3.1. Technology Transition

3.2. A Mission Configurable Wing

3.3. Improved Flaps and Ailerons

4. Morphing as a Solution

4.1. Wing and Control Surface Feasible Solutions

4.2. Some Specific Requirements

5. Conclusions

References

Chapter 3: The Development of Morphing Aircraft Benefit Assessment

1. Experiments as Basis for Morphing Progress

2. The Advent of Transonic Methods

3. Automated Methods as Enabler for Large Scale Studies

4. Reintroduction of Flexible Materials

5. The Final Step to Industrial Application

References

Section 2: Requirements and Performance

Chapter 4: Span Morphing Concept: An Overview

1. Introduction

2. Effects of Span Increase

2.1. Aerodynamic Effects

2.2. Structural Effects

2.3. Stability and Control Effects

3. Span Morphing Concepts and Aircraft Performance

3.1. Symmetric Span Morphing

3.1.1. Aerodynamic aspects of span morphing

3.1.2. Structural and performance aspects of span morphing

3.1.3. Scalability aspects of span morphing

3.2. Asymmetric Span Morphing

3.2.1. Actuation speed requirements

3.2.2. CG position shifts and inertial effects

4. Implementation Challenges

4.1. Telescopic Wings

4.2. Hinged Structures

4.3. Twin Spars

4.3.1. Elastic skins

5. Conclusions

Acknowledgments

References

Chapter 5: Adjoint-Based Aerodynamic Shape Optimization Applied to Morphing Technology on a Regional Aircraft Wing

1. Introduction

2. Handling of Morphing Shape Changes in a CFD Context

2.1. Context of the Study

2.2. Discrete Model of Displacement Field at the Trailing Edge

2.3. 3D CFD Mesh Deformation Technique

3. CFD Evaluation and Far-Field Drag Analysis Over a Wing Equipped with a Morphing System

3.1. Finite-Volume Solver for the RANS Equations in elsA

3.2. Far-Field Drag Extraction Tool

4. Sensitivity Analysis Using a Discrete Adjoint of the RANS Equations

4.1. Residual and Objective Function Dependencies

4.2. Discrete Adjoint Method in elsA

5. Local Shape Optimization Technique

5.1. Definition of the Problem

5.2. The Method of Feasible Directions

5.3. A 2D Example: The Rosenbrock's Function Constrained by a Disk

6. Aerodynamic Shape Optimization of Morphing System: An Application Within the EU Project SARISTU

6.1. Optimization Problem

6.2. Optimization Loop Presentation

6.3. First Optimization

6.4. Second Optimization

6.5. Expectations on Morphing Technology

7. Conclusion

References

Further Reading

Chapter 6: Expected Performances

1. Introduction

2. The Reference Aircraft

3. Active Camber Using Conventional Control Surfaces

3.1. Five Panels Over the Flap Region

4. Coupled Aerostructural Shape Optimization

4.1. Morphing Leading Edge

4.2. Morphing Trailing Edge

5. Fuel Savings

6. High-Fidelity Aerodynamic Analysis

6.1. Leading Edge Morphing

6.2. Trailing Edge Morphing

7. Weight Saving

7.1. Morphing Devices

8. Benefit Exploitation in the Transport Aircraft Design

9. Conclusions

Acknowledgments

References

Section 3: Morphing Skins

Chapter 7: Morphing Skin: Foams

1. Introduction

2. Design Principles

3. Low Temperature Elastomers

4. Material Properties of HYPERFLEX

5. Properties of Bonded Joints

6. Properties of Morphing Skin

7. Skin Manufacturing

8. Summary and Conclusions

References

Chapter 8: The Design of Skin Panels for Morphing Wings in Lattice Materials

1. Introduction

2. Requirements for the Skin of a Morphing Wing

3. A Methodology for Nonlinear Homogenization of Periodic Structures

4. Mechanical Properties of Skin Panels in Lattice Material

4.1. Analysis of Selected Lattice Topologies

4.2. The Design Space of the Chevron Lattice

5. Conclusions

References

Chapter 9: Composite Corrugated Laminates for Morphing Applications

1. Introduction

2. Types of Corrugated Laminates

3. Anisotropy and Stiffness Properties in Morphing Direction

3.1. Anisotropy Indices of Stiffness Properties

3.2. Compliance in Morphing Directions of Different Types of Composite Corrugated Laminates

4. Strength and Stiffness Contributions in Nonmorphing Directions

4.1. Failure Modes of Composite Corrugated Laminates and Strain Limits

4.2. Evaluation of Structural Stiffness Contribution in Nonmorphing Directions

5. Manufacturing of Composite Corrugated Laminates

6. Development of Aerodynamically Efficient Morphing Skins

6.1. Aerodynamic Issues in the Application of Composite Corrugated Laminates

6.2. Performance Index Based on Ratio Between Bending and Axial Compliance

6.3. Integration of an Elastomertic Cover on a Square-Shaped Corrugated Laminate

7. Conclusions

References

Section 4: Systems Design

Chapter 10: Active Metal Structures

1. Introduction

2. Morphing Oriented Kinematic Chains: Working Principles and Design Approaches

2.1. Spar Caps Section Area at Generic Cross-section

2.2. Spars Webs, Skin Panels, Rib Plate Thickness at Generic Cross-Section

3. Compliant Mechanisms: Working Principles and Design Approaches

4. Applications of Morphing Oriented Kinematic Chains

4.1. Morphing Concept Overview

4.2. Structural Analyses

5. Applications of the Compliant Mechanism Approach

5.1. Arc-Based Flap, Actuated by SMA Active Elements

5.2. X-Cell Architecture for a Single Slotted Flap

6. Conclusions

References

Chapter 11: Sensor Systems for Smart Architectures

1. Introduction

2. Strain Sensors

2.1. Strain Gauge Foils

2.2. Piezoelectric Devices

2.3. Graphene-Based Polymers

2.4. Fiber Optics

2.4.1. Associated Electronics

2.4.2. Connectors

2.4.3. Splicers

3. Sensor Systems for Large Scale Integration

3.1. Wireless Technology

3.2. Sprayed Technology

3.3. Distributed Technology

3.4. Some Installation Issues

4. Case Studies

4.1. Shape Reconstruction of a Variable Camber Wing Trailing Edge

4.2. Damage and Load Monitoring

4.3. Rotation Angle Monitoring

5. Conclusions and Perspectives

References

Chapter 12: Control Techniques for a Smart Actuated Morphing Wing Model: Design, Numerical Simulation and Experimental Va ...

1. Introduction

2. Project Background

3. General Structures of the Open Loop and Closed Loop Control Architectures

4. Open Loop Controllers

4.1. Fuzzy Logic PD Controller

4.2. Combined On-Off and PID Fuzzy Logic Controller

4.3. Combined On-Off and Cascade PD-PI Fuzzy Logic Controller

4.4. Combined On-Off and Self-Tuning Fuzzy Logic Controller

5. Optimized Closed Loop Control Method

6. Conclusions

Acknowledgments

References

Section 5: Numerical Simulation

Chapter 13: Influence of the Elastic Constraint on the Functionality of Integrated Morphing Devices

1. Introduction

2. Features of the FE Models

2.1. LE Modeling Strategy

2.2. TE Modeling Strategy

2.3. WL Modeling Strategy

3. Isolated Devices Behavior

4. Global Stiffness of the Outer Wing Box

5. Effects of the Actuation of the Morphing Devices

5.1. Cross Effects

5.2. Effects on the Wing Box

6. Conclusions and Further Steps

References

Chapter 14: Application of the Extra-Modes Method to the Aeroelastic Analysis of Morphing Wing Structures

1. Introduction

2. Aeroelastic Equilibrium Equation and Stability

3. Extra-Modes Formulation

4. Aeroelastic Analyses of Morphing Wings Using the Extra-Modes Method

4.1. Effectiveness of Wing Twist Morphing as Roll Control Strategy

4.2. Trade-Off Flutter Analysis of a Morphing Wing Trailing Edge

5. Conclusions

References

Chapter 15: Stress Analysis of a Morphing System

1. Introduction

2. Design of a Morphing Structure

3. Finite Element Modeling of Morphing Structures

3.1. Rib and Spars

3.2. Fasteners

3.3. Skin

3.4. Actuation System

4. Design Loads and Constraints

5. Structural Design and Simulations

5.1. Static Analysis at Limit and Ultimate Loads: Linear and Nonlinear Analysis

5.2. Stress Analysis

5.3. Buckling Analysis

5.4. Modal Analysis

6. Stress Margins of Safety

6.1. Solid Parts

6.2. Internal Connections

6.2.1. Fasteners

6.2.2. Lugs and Bushings

6.2.3. MOS Summary

7. Conclusions

References

Further Readings

Section 6: Morphing Wing Systems

Chapter 16: Morphing of the Leading Edge

1. Summary

2. Introduction

3. Conceptual Approach to the Morphing of the Leading Edge

4. Working Principle of the Architecture Selected to Produce the Drop Nose Effect

5. Architecture Design

5.1. Identification of the Kinematic Chain in the Rib Plane

5.2. Topologic Optimization of the In-Plane Rib Architecture

5.3. Spanwise Architecture and Actuation Design

5.4. Modelling and Working Simulation of the Complete Architecture

6. Prototyping

7. Experimental Campaign

7.1. The Setup

7.2. Experimental Results

7.3. Numerical—Experimental Comparison

8. Conclusions and Further Steps

References

Chapter 17: An Adaptive Trailing Edge

1. Introduction

2. The Concept

2.1. Layout

2.1.1. The structural architecture

2.1.2. The skin system

2.1.3. The actuation system

2.1.4. The sensor system

2.1.5. The control logic

3. Design

3.1. Design Loads

3.2. Structural Sizing

3.3. Actuator Selection

3.4. Results

3.4.1. Finite element analysis

3.4.2. Shape control

3.4.3. Damping levels

3.4.4. Flutter analysis

4. Safety and Reliability Aspects

4.1. Generalities

4.2. Distributed Actuation

4.3. The ATED Function

4.4. Fault Hazard Assessment

4.5. Functional Hazard Assessment

5. Discussion: Implementation on Real Aircraft

5.1. System Development

5.2. Operational Aspects

5.3. Aeroelastic Issues

6. Conclusions and Future Developments

Acknowledgments

References

Further Reading

Chapter 18: Morphing Aileron

1. Introduction

2. Conceptual Approach

3. Working Principle and T/A Architecture

4. Actuation System Design

5. Numerical Simulations

5.1. Interface Load

6. Prototyping

7. Experimental Tests and Main Outcome

7.1. GVT and Numerical Correlation

7.2. Functionality Test

7.3. Experimental Shapes

8. Wind Tunnel Tests

9. Conclusions

References

Section 7: Full Scale Realization, Safety, and Reliability

Chapter 19: Morphing Technology for Advanced Future Commercial Aircrafts

1. Introduction

2. ATED Manufacturing

2.1. The Morphing System

2.2. Manufacturing

2.3. Assembly

2.4. Test Campaign

2.5. Conclusions

3. Other Experiences

3.1. 3AS Project

3.2. CURVED Project

4. Future Studies—The Morphing Rudder

4.1. Synthesis

4.2. Manufacturing Challenges

4.3. Lateral Directional Stability Analysis

4.3.1. Static stability analysis

4.3.2. Dynamic stability analysis

5. Conclusions

References

Further Reading

Chapter 20: Morphing Wing Integration

1. Introduction

2. Demonstrator Components

2.1. Wing Box Primary Structure

2.2. Leading Edge

2.3. Trailing Edge

2.4. Winglet

3. Conditions of Assembly

4. Jig

5. Equipment and Tooling

6. Demonstrator Assembly

6.1. The Assembly of the Wing Box

6.2. Morphing Systems Installation: The Leading Edge

6.3. Morphing Systems Installation: The Trailing Edge

6.4. Morphing Systems Installation: The Winglet

7. FBG Sensor Network

8. Conclusions

Acknowledgments

References

Chapter 21: Morphing Devices: Safety, Reliability, and Certification Prospects

1. Introduction

2. System Level Approaches to the Certification of Morphing Wing Devices

2.1. Adaptive Droop Nose

2.2. Adaptive Trailing Edge Device

2.3. Morphing Winglet

2.4. Defining the System Level Functions of Morphing Devices

2.5. Dual Level Safety

3. Functional Hazard Assessment

4. Dual-Level Approach for the FTA of a Morphing Wing

5. Common Cause Analyses

5.1. Particular Risk Analysis

5.2. Common Mode Analysis

5.3. Zonal Safety Analysis

6. Conclusions

References

Chapter 22: On the Experimental Characterization of Morphing Structures

1. Introduction

2. Testing Practices for Morphing Systems

2.1. Morphing Trailing Edge Device

3. Unit Tests: From Component to Morphing System Verification

3.1. Skin Over Dummy

3.1.1. Pressure-induced skin deformation

3.1.2. Skin normal modes

3.2. Actuators Over Dummy

3.3. Control System Over Dummy

3.3.1. Static and dynamic tests

3.4. Control System Over Skinned Dummy

3.5. Complete System

3.5.1. Modal analysis—Free-free boundary conditions

3.5.2. Static tests—FF control—Loaded/unloaded conditions

3.5.3. Static tests—FB control—Loaded/unloaded conditions

3.5.4. Static tests—Skin bubbling effects

3.5.5. Modal analysis—Clamped conditions—FF control

3.5.6. Modal analysis—Clamped conditions—FB control

4. System Integration Test Bench for Morphing Systems

5. Full-Scale Testing

5.1. Shape Control of Adaptive Wings

5.2. Wing Shape Controller Strategies and Experimental Verification

6. Conclusions

References

Chapter 23: Wind Tunnel Testing of Adaptive Wing Structures

1. Introduction

1.1. General Test Procedure for the Morphing Item

2. 3AS

2.1. Requirements for the EURAM and Experimental Facilities

2.2. Model Design and Manufacture

2.3. Laboratory Tests

2.4. Aeroelastic Wing Tip Controls Concept

2.5. All-Movable Vertical Tail Concept

2.6. Selective Deformable Structure Concept

3. SADE

3.1. Wing Demonstrator

3.2. Videogrammetry Method of Deformation Measuring

3.3. Test Object and Experimental Facility

3.4. Measuring Process and Data Handling

4. SARISTU

4.1. Objectives of the Wind Tunnel Test

4.2. Ground Vibration Test and Flutter Expansion Test

4.3. Load Measurements

4.4. Calculations of Wing Demo Aerodynamics in T-104 WT

4.5. Deformations Measurements of the Wing with Elastic Controls in WT T-104 Flow

5. Conclusions

Acknowledgments

References

Section 8: Smart Helicopters

Chapter 24: Rotary Wings Morphing Technologies: State of the Art and Perspectives

1. Introduction

2. Overview of Rotor Morphing Technologies

2.1. Trailing Edge Flaps

2.1.1. Piezo ceramic-based trailing edge flap actuation

2.1.2. Nonpiezo-based trailing edge flap actuation

2.1.3. Gurney flap

2.2. Active and Variable Twist

2.2.1. High frequency active twist rotor designs

2.2.2. Quasi-static variable twist rotor designs

2.3. Variable Span

2.4. Emerging Rotor Morphing Technologies

2.4.1. Variable chord rotor systems

2.4.2. Variable camber rotor systems

2.4.3. Variable nose droop rotor systems

2.4.4. Variable rotor speed systems

3. Critical Review of Some Significant Efforts

3.1. Active Trailing and Leading Edge Devices

3.2. Individual Blade Control

3.2.1. IBC concept

3.2.2. Demonstrated benefits

3.2.3. Examples of IBC projects

3.2.4. Maturity, benefits, and drawbacks

3.3. Active Twist

3.4. Variable Span

3.5. Slowed/Stopped Rotor

4. Conclusions

References

Chapter 25: Aerodynamic Analyses of Tiltrotor Morphing Blades

1. Introduction

2. Aim and Structure of the Chapter

3. Research Context

4. Outline of Methods and Numerical Tools

4.1. Integration and Optimization Environment

4.2. MDA Procedures and Optimization Processes

4.2.1. MDA

4.2.2. Optimization

4.2.3. Two level optimization

4.3. BEMT Analysis

4.3.1. Description

4.3.2. Validation

4.4. CFD Driven Analysis

4.5. Blade Parameterization

4.5.1. Planform

4.5.2. Blade length morphing

4.5.3. Airfoil geometry morphing

4.6. Airfoil Selection

4.7. Surface Grid Generation

4.8. Volume Grid Generation

5. Background

6. Case Study

6.1. Description of Activities

6.2. Baseline Geometry

6.3. Optimization Objectives and Strategy

7. Un-Morphed Blades

8. Morphing Blades

8.1. Blade Span Morphing and Variable Speed Rotor

8.2. Blade Section Morphing

8.2.1. Geometry morphing states

9. Conclusions

References

Chapter 26: Synergic Effects of Passive and Active Ice Protection Systems

1. Introduction

2. Pros and Cons of Considered IPS

2.1. Thermoelectric IPS

2.2. Low-Power Consuming Piezoelectric Deicing Systems

2.3. Hydrophobic Coatings

2.4. Alternative Strategy Based on a Hybrid Approach

3. Design and Realization of the IPS

3.1. Hydrophobic Coating Design and Process Assessment

3.2. Thermoelectric system design and ice shedding prediction

3.3. Piezoelectric IPS Sizing and Parameters Assessment

4. Experimental Validation

4.1. First WT Test Campaign

4.2. Second WT Test Campaign

5. Conclusions

Acknowledgments

References

Further Reading

Chapter 27: Helicopter Vibration Reduction

1. Introduction

2. NextGen Vibration Levels

3. Vibration Specifications

4. Source of Helicopter Vibratory Loads

5. How Do Vibratory Loads Get Into the Fuselage?

6. What Is Used for Vibration Control Now?

6.1. Why Not Isolation?

6.2. The Venerable Frahm

6.3. Fuselage-Based Frahms

6.4. Rotor-Based Frahms

6.5. Frahms Are Heavy

6.6. Active Vibration Control

6.7. Dynamic Antiresonant Vibration Isolator

7. More Problems With Frahms

8. Active Counter-Force

8.1. Higher Harmonic Control

9. Individual Blade Control

9.1. Hydraulic IBC

9.2. Electrical IBC

9.3. On-Blade Flaps

10. The Path Forward

Acknowledgments

References

Afterword

Index

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