Advanced Structural Damage Detection: From Theory to Engineering Applications

Structural Health Monitoring (SHM) is the interdisciplinary engineering field devoted to the monitoring and assessment of structural health and integrity. SHM technology integrates non-destructive evaluation techniques using remote sensing and smart materials to create smart self-monitoring structures characterized by increased reliability and long life. Its applications are primarily systems with critical demands concerning performance where classical onsite assessment is both difficult and expensive.

Advanced Structural Damage Detection: From Theory to Engineering Applications is written by academic experts in the field and provides students, engineers and other technical specialists with a comprehensive review of recent developments in various monitoring techniques and their applications to SHM. Contributing to an area which is the subject of intensive research and development, this book offers both theoretical principles and feasibility studies for a number of SHM techniques.

Advanced Structural Damage Detection: From Theory to Engineering Applications is a comprehensive reference for researchers and engineers and is a useful source of information for graduate students in mechanical and civil engineering

List of Contributors xi

Preface xiii

Acknowledgments xvii

1 Introduction 1

1.1 Introduction 1

1.2 Structural Damage and Structural Damage Detection 2

1.3 SHM as an Evolutionary Step of NDT 4

1.4 Interdisciplinary Nature of SHM 5

1.5 Structure of SHM Systems 9

1.5.1 Local SHM Methods 9

1.5.2 Global SHM Methods 10

1.6 Aspects Related to SHM Systems Design 12

1.6.1 Design Principles 13

References 15

2 Numerical Simulation of ElasticWave Propagation 17

2.1 Introduction 17

2.2 Modelling Methods 18

2.2.1 Finite Difference Method 19

2.2.2 Finite Element Method 20

2.2.3 Spectral Element Method 21

2.2.4 Boundary Element Method 23

2.2.5 Finite Volume Method 24

2.2.6 Other Numerical Methods 25

2.2.7 Time Discretization 27

2.3 Hybrid and Multiscale Modelling 29

2.4 The LISA Method 33

2.4.1 GPU Implementation 36

2.4.2 Developed GPU-Based LISA Software Package 37

2.4.3 cuLISA3D Solver’s Performance 38

2.5 Coupling Scheme 39

2.6 Damage Modelling 47

2.7 Absorbing Boundary Conditions for Wave Propagation 48

2.8 Conclusions 50

References 51

3 Model Assisted Probability of Detection in Structural Health Monitoring 57

3.1 Introduction 57

3.2 Probability of Detection 58

3.3 Theoretical Aspects of POD 59

3.3.1 Hit/Miss Analysis 59

3.3.2 Signal Response Analysis 61

3.3.3 Confidence Bounds 63

3.3.4 Probability of False Alarm 64

3.4 From POD to MAPOD 64

3.5 POD for SHM 65

3.6 MAPOD of an SHM System Considering Flaw Geometry

Uncertainty 66

3.6.1 SHM System 66

3.6.2 Simulation Framework 67

3.6.3 Reliability Assessment 67

3.7 Conclusions 70

References 71

4 Nonlinear Acoustics 73

4.1 Introduction 73

4.2 Theoretical Background 75

4.2.1 Contact Acoustics Nonlinearity 76

4.2.2 Nonlinear Resonance 79

4.2.3 Frequency Mixing 80

4.3 Damage Detection Methods and Applications 85

4.3.1 Nonlinear Acoustics for Damage Detection 87

4.4 Conclusions 103

References 104

5 Piezocomposite Transducers for Guided Waves 109

5.1 Introduction 109

5.2 Piezoelectric Transducers for Guided Waves 110

5.2.1 Piezoelectric Patches 110

5.2.2 Piezocomposite Based Transducers 111

5.2.3 Interdigital Transducers 113

5.3 Novel Type of IDT-DS Based on MFC 118

5.4 Generation of Lamb Waves using Piezocomposite Transducers 120

5.4.1 Numerical Simulations 120

5.4.2 Experimental Verification 122

5.4.3 Numerical and Experimental Results 124

5.4.4 Discussion 129

5.5 Lamb Wave Sensing Characteristics of the IDT-DS4 131

5.5.1 Numerical Simulations 132

5.5.2 Experimental Verification 133

5.6 Conclusions 136

Appendix 136

References 137

6 Electromechanical Impedance Method 141

6.1 Introduction 141

6.2 Theoretical Background 142

6.2.1 Definition of the Electromechanical Impedance 143

6.2.2 Measurement Techniques 144

6.2.3 Damage Detection Algorithms 146

6.3 Numerical Simulations 147

6.3.1 Modelling Electromechanical Impedance with the use of FEM 147

6.3.2 Uncertainty and Sensitivity Analyses 150

6.3.3 Discussion 153

6.4 The Developed SHM System 155

6.5 Laboratory Tests 158

6.5.1 Experiments Performed for Plate Structures 159

6.5.2 Condition Monitoring of a Pipeline Section 161

6.5.3 Discussion 163

6.6 Verification of the Method on Aircraft Structures 165

6.6.1 Monitoring of a Bolted Joint in the Main Undercarriage Bay 165

6.6.2 Monitoring of a Riveted Fuselage Panel 168

6.6.3 Discussion 172

6.7 Conclusions 173

References 174

7 Beamforming of Guided Waves 177

7.1 Introduction 177

7.2 Theory 179

7.2.1 Imaging Using Synthetic Aperture 179

7.2.2 Effective Aperture Concept 183

7.2.3 Imaging Schemes 185

7.2.4 Self-Focusing Arrays 187

7.3 Numerical Results 190

7.3.1 Examples of Effective Aperture 190

7.3.2 Imaging Using Star-like Array 192

7.3.3 Numerical Verification of the DORT-CWT Method 196

7.4 Experimental Results 199

7.4.1 Experimental Setup 199

7.4.2 Experimental Evaluation of Sensing Array 200

7.4.3 Experimental Evaluation of Effective Aperture 201

7.4.4 Damage Imaging Using Synthetic Aperture 203

7.4.5 Experimental Validation of the DORT-CWT Method 203

7.4.6 Damage Imaging Using Self-Focused Transmitting Array 206

7.5 Discussion 207

7.6 Conclusions 209

References 210

8 Modal Filtering Techniques 213

8.1 Introduction 213

8.2 State of the Art 214

8.3 Formulation of the Method 219

8.4 Numerical Verification of the Method 222

8.4.1 Models Used for Simulation 223

8.4.2 Testing Procedure 224

8.4.3 Results of Analyses 226

8.4.4 Model Based Probability of Detection 230

8.5 Monitoring System Based on Modal Filtration 231

8.5.1 Main Assumptions 231

8.5.2 Measuring Diagnostic Unit 232

8.5.3 Modal Analysis and Modal Filtration Software 234

8.6 Laboratory Tests 235

8.6.1 Programme of Tests 235

8.6.2 Results of Experiments 237

8.6.3 Probability of Detection Analysis 239

8.7 Operational Tests 245

8.8 Summary 248

References 248

9 Vibrothermography 251

9.1 Introduction 251

9.2 State of the Art in Thermographic Nondestructive Testing 252

9.3 Developed Vibrothermographic Test System 261

9.4 Virtual Testing 263

9.5 Laboratory Testing 269

9.6 Field Measurements 273

9.7 Summary and Conclusions 275

References 275

10 Vision-Based Monitoring System 279

10.1 Introduction 279

10.2 State of the Art 281

10.3 Deflection Measurement by Means of Digital Image Correlation 282

10.4 Image Registration and Plane Rectification 284

10.5 Automatic Feature Detection and Matching 287

10.5.1 Deflection-Shaped Based Damage Detection and Localization 289

10.6 Developed Software Tool 291

10.7 Numerical Investigation of the Method 291

10.7.1 Numerical Modelling of the Developed Vision Measurement

System 292

10.7.2 Uncertainty Investigation of the Method 292

10.7.3 Model Based Probability of Damage Detection 297

10.8 Laboratory Investigation of the Method 301

10.8.1 Tests of the Method on the Laboratory Setup 303

10.8.2 The Probability of Detection of the Method in the

Laboratory Investigation 307

10.8.3 Investigation of the Developed Method’s Accuracy 309

10.9 Key Studies and Evaluation of the Method 314

10.9.1 Tram Viaduct Deflection Monitoring 314

10.10 Conclusions 318

References 318

Index 321