Health Monitoring of Aerospace Structures: Smart Sensor Technologies and Signal Processing

288 Pages·2004·3.26 MB·English

by  Wieslaw Staszewski

Health Monitoring
of Aerospace Structures
Smart Sensor Technologies
and Signal Processing
EDITED BY
W.J. Staszewski, C. Boller∗ and G.R. Tomlinson
DepartmentofMechanicalEngineering,SheffieldUniversity,UK
∗FormerlywithEuropeanAeronauticDefenceandSpaceCompany–EADS,Munich,Germany

Health Monitoring
of Aerospace Structures

Health Monitoring
of Aerospace Structures
Smart Sensor Technologies
and Signal Processing
EDITED BY
W.J. Staszewski, C. Boller∗ and G.R. Tomlinson
DepartmentofMechanicalEngineering,SheffieldUniversity,UK
∗FormerlywithEuropeanAeronauticDefenceandSpaceCompany–EADS,Munich,Germany
Copyright2004 JohnWiley&SonsLtd,TheAtrium,SouthernGate,Chichester,
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LibraryofCongressCataloging-in-PublicationData
Healthmonitoringofaerospacestructures:smartsensortechnologiesandsignal
processing/editedbyW.J.Staszewski,C.Boller,G.R.Tomlinson.
p.cm.
Includesbibliographicalreferencesandindex.
ISBN0-470-84340-3(alk.paper)
1.Airplanes–Inspection.2.Airframes–Deterioration.3.Spacevehicles–Inspection.4.
Detectors.I.Staszewski,W.J.II.boller,Chr.III.Tomlinson,GeoffreyR.
TL671.7.H432003
629.134(cid:2)6–dc22
2003057607
BritishLibraryCataloguinginPublicationData
AcataloguerecordforthisbookisavailablefromtheBritishLibrary
ISBN0-470-84340-3
Typesetin10/12ptTimesbyLaserwordsPrivateLimited,Chennai,India
PrintedandboundinGreatBritainbyTJInternational,Padstow,Cornwall
Thisbookisprintedonacid-freepaperresponsiblymanufacturedfromsustainableforestry
inwhichatleasttwotreesareplantedforeachoneusedforpaperproduction.
Contents
List of Contributors xi
Preface xvii
1 Introduction 1
G. Bartelds, J.H.Heida,J. McFeatandC. Boller
1.1 Health and Usage Monitoring in Aircraft Structures – Why and How? 1
1.2 Smart Solution in Aircraft Monitoring 2
1.3 End-User Requirements 4
1.3.1 Damage Detection 5
1.3.2 Load History Monitoring 7
1.4 Assessment of Monitoring Technologies 8
1.5 Background of Technology Qualification Process 12
1.6 Technology Qualification 17
1.6.1 Philosophy 17
1.6.2 Performance and Operating Requirements 20
1.6.3 Qualification Evidence – Requirements and Provision 20
1.6.4 Risks 24
1.7 Flight Vehicle Certification 25
1.8 Summary 28
References 28
2 Aircraft Structural Health and Usage Monitoring 29
C.Boller and W.J.Staszewski
2.1 Introduction 29
2.2 Aircraft Structural Damage 30
2.3 Ageing Aircraft Problem 35
2.4 LifeCycle Cost of Aerospace Structures 36
2.4.1 Background 37
2.4.2 Example 38
2.5 Aircraft Structural Design 42
2.5.1 Background 42
2.5.2 Aircraft Design Process 46
vi CONTENTS
2.6 Damage Monitoring Systems in Aircraft 47
2.6.1 Loads Monitoring 47
2.6.2 Fatigue Monitoring 48
2.6.3 Load Models 51
2.6.4 Disadvantages of Current Loads Monitoring Systems 52
2.6.5 Damage Monitoring and Inspections 53
2.7 Non-Destructive Testing 54
2.7.1 Visual Inspection 54
2.7.2 Ultrasonic Inspection 54
2.7.3 Eddy Current 56
2.7.4 Acoustic Emission 56
2.7.5 Radiography, Thermography and Shearography 58
2.7.6 Summary 59
2.8 Structural Health Monitoring 61
2.8.1 Vibration and Modal Analysis 61
2.8.2 Impact Damage Detection 62
2.9 Emerging Monitoring Techniques and Sensor Technologies 65
2.9.1 Smart Structures and Materials 65
2.9.2 Damage Detection Techniques 66
2.9.3 Sensor Technologies 68
2.9.4 Intelligent Signal Processing 68
2.10 Conclusions 70
References 71
3 Operational Load Monitoring Using Optical Fibre Sensors 75
P. Foote, M. Breidne,K. Levin,P. Papadopolous, I. Read,M. Signorazzi,
L.K.Nilsson, R. Stubbe and A. Claesson
3.1 Introduction 75
3.2 Fibre Optics 76
3.2.1 Optical Fibres 76
3.2.2 Optical Fibre Sensors 77
3.2.3 Fibre Bragg Grating Sensors 78
3.3 Sensor Target Specifications 79
3.4 Reliability of Fibre Bragg Grating Sensors 81
3.4.1 Fibre Strength Degradation 81
3.4.2 Grating Decay 83
3.4.3 Summary 85
3.5 Fibre Coating Technology 86
3.5.1 Polyimide Chemistry and Processing 86
3.5.2 Polyimide Adhesion to Silica 88
3.5.3 Silane Adhesion Promoters 89
3.5.4 Experimental Example 91
3.5.5 Summary 96
3.6 Example of Surface Mounted Operational Load Monitoring Sensor
System 99
3.6.1 Sensors 101
CONTENTS vii
3.6.2 Optical Signal Processor 108
3.6.3 Optical Interconnections 110
3.7 Optical Fibre Strain Rosette 111
3.8 Example of Embedded Optical Impact Detection System 111
3.9 Summary 121
References 122
4 Damage Detection Using Stress and Ultrasonic Waves 125
W.J.Staszewski, C.Boller, S. Grondel, C.Biemans, E. O’Brien, C. Delebarre
and G.R.Tomlinson
4.1 Introduction 125
4.2 Acoustic Emission 126
4.2.1 Background 126
4.2.2 Transducers 126
4.2.3 Signal Processing 127
4.2.4 Testing and Calibration 129
4.3 Ultrasonics 129
4.3.1 Background 129
4.3.2 Inspection Modes 131
4.3.3 Transducers 131
4.3.4 Display Modes 132
4.4 Acousto-Ultrasonics 133
4.5 Guided Wave Ultrasonics 136
4.5.1 Background 136
4.5.2 Guided Waves 136
4.5.3 Lamb Waves 136
4.5.4 Monitoring Strategy 139
4.6 Piezoelectric Transducers 141
4.6.1 Piezoelectricity and Piezoelectric Materials 141
4.6.2 Constitutive Equations 142
4.6.3 Properties 145
4.7 Passive Damage Detection Examples 147
4.7.1 Crack Monitoring Using Acoustic Emission 147
4.7.2 Impact Damage Detection in Composite Materials 149
4.8 Active Damage Detection Examples 151
4.8.1 Crack Monitoring in Metallic Structures Using Broadband
Acousto-Ultrasonics 151
4.8.2 Impact Damage Detection in Composite Structures Using Lamb
Waves 156
4.9 Summary 161
References 161
5 Signal Processing for Damage Detection 163
W.J.Staszewskiand K. Worden
5.1 Introduction 163
5.2 Data Pre-Processing 165
viii CONTENTS
5.2.1 Signal Smoothing 165
5.2.2 Signal Smoothing Filters 165
5.3 Signal Features for Damage Identification 166
5.3.1 Feature Extraction 166
5.3.2 Feature Selection 166
5.4 Time–Domain Analysis 167
5.5 Spectral Analysis 167
5.6 Instantaneous Phase and Frequency 169
5.7 Time–Frequency Analysis 171
5.8 Wavelet Analysis 173
5.8.1 Continuous Wavelet Transform 173
5.8.2 Discrete Wavelet Transform 175
5.9 Dimensionality Reduction Using Linear and Nonlinear Transformation 177
5.9.1 Principal Component Analysis 178
5.9.2 Sammon Mapping 178
5.10 Data Compression Using Wavelets 180
5.11 Wavelet-Based Denoising 181
5.12 Pattern Recognition for Damage Identification 183
5.13 Artificial Neural Networks 185
5.13.1 Parallel Processing Paradigm 186
5.13.2 The Artificial Neuron 187
5.13.3 Multi-Layer Networks 188
5.13.4 Multi-Layer Perceptron Neural Networks and Others 188
5.13.5 Applications 191
5.14 Impact Detection in Structures Using Pattern Recognition 192
5.14.1 Detection of Impact Positions 194
5.14.2 Detection of Impact Energy 195
5.15 Data Fusion 195
5.16 Optimised Sensor Distributions 199
5.16.1 Informativeness of Sensors 199
5.16.2 Optimal Sensor Location 200
5.17 Sensor Validation 203
5.18 Conclusions 203
References 203
6 Structural Health Monitoring Evaluation Tests 207
P.A.Lloyd, R. Pressland, J. McFeat,I. Read, P. Foote, J.P.Dupuis,
E. O’Brien,L. Reithler, S. Grondel,C. Delebarre,K. Levin,C.Boller,
C.Biemans and W.J.Staszewski
6.1 Introduction 207
6.2 Large-Scale Metallic Evaluator 208
6.2.1 Lamb Wave Results from Riveted Metallic Specimens 208
6.2.2 Acoustic Emission Results from a Full-Scale Fatigue Test 211
6.3 Large-Scale Composite Evaluator 215
6.3.1 Test Article 215
6.3.2 Sensor and Specimen Integration 216