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Preface |
6 |
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Contents |
8 |
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Structural Health Monitoring – Its Association and Use |
9 |
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1 A Motivation for Structural Health Monitoring |
9 |
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2 Loads and Overloads |
19 |
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3 Fatigue, Fracture and Damage Tolerance |
26 |
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3.1 Fatigue |
26 |
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3.2 Fracture and Damage Tolerance |
30 |
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3.3 SHM, Loads Monitoring and Damage Tolerance |
43 |
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4 Non-Destructive Evaluation – Some Basic Principles |
44 |
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4.1 Historic Background |
44 |
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4.2 Magnetism |
45 |
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4.3 Electromagnetic Ultrasound (EMUS) |
54 |
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4.4 Eddy Current |
55 |
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4.5 Ultrasonics |
58 |
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4.6 Other Conventional NDT Techniques and Emerging Technologies |
58 |
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5 Non-Destructive Evaluation in Composite Materials |
62 |
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6 Approaches to Structural Health Monitoring |
67 |
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7 Emerging SHM Applications and Concluding Remarks |
80 |
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Bibliography |
84 |
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Further Reading |
87 |
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Structural Health Monitoring of Aircraft Structures |
88 |
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1 Introduction |
88 |
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2 Structural Health Monitoring Architectures |
90 |
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2.1 Sensors Network Architecture |
91 |
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2.2 Phased Arrays Architecture |
94 |
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3 Piezoelectric Networks |
97 |
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3.1 Damage Detection: Metallic Plates |
100 |
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3.2 Development of a PCB Board for System Automation |
107 |
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3.3 Damage Detection: Composite Plates |
109 |
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3.4 Initial Acoustic Emission Experiments |
115 |
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4 Phased Arrays |
119 |
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4.1 Dispersion Curves |
122 |
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4.2 Tuned Lamb Waves: Mode, Frequency and Transducer Selection |
123 |
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4.3 Number of Elements in the Array |
125 |
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4.4 Phased Array Actuation System |
126 |
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4.5 Damage Detection Algorithms |
129 |
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4.6 Damage Detection: Metallic Plates |
134 |
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5 SHM using Fiber Optic Sensors |
137 |
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5.1 Fiber Bragg Grating Sensors |
141 |
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5.2 Etched Fiber Sensors |
141 |
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5.3 Sensor Characterization |
142 |
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5.4 Flow Monitoring |
144 |
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5.5 Flow Monitoring of Panel Specimen |
144 |
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5.6 Flow Monitoring of 3D Semicircle Specimen |
146 |
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5.7 Strain Sensitivity Characterization |
148 |
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5.8 Strain Sensitivity of Panel Specimen |
150 |
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5.9 Strain Sensitivity of Semicircular Specimen |
151 |
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6 Concluding Remarks |
152 |
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Bibliography |
153 |
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Vibration-Based Damage Diagnosis and Monitoring of External Loads |
156 |
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1 Introduction |
156 |
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2 Modeling and Diagnosis of Damaged Systems |
158 |
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2.1 General Non-Linear Dynamical Model |
158 |
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2.2 Feature Extraction |
159 |
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2.3 Residual Vector and Damage Indicator |
160 |
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2.4 Model-Based Diagnostics vs. Data-Based Damage Detection |
161 |
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3 Diagnosis of Linear Systems |
164 |
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3.1 Equation of Motion and State Space Representation |
164 |
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3.2 Damage Identification in the Modal Domain |
165 |
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3.3 Electro-Mechanical Impedance Method (EMIM) |
167 |
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3.4 Time Domain Methods |
168 |
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4 Data-based Damage Detection under Changing Environmental and Operational Conditions (EOC) |
173 |
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4.1 Overview of Methods |
173 |
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4.2 Environmental and operational conditions for wind energy plants |
174 |
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4.3 Compensation of environmental effects on damage detection approach using fuzzy classification |
175 |
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4.4 Example: Wind turbine |
178 |
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5 Reconstruction of External Loads |
180 |
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5.1 Problem overview and previous work |
180 |
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5.2 Design of Simultaneous state and input estimator |
192 |
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5.3 Application Examples |
200 |
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6 Conclusions |
205 |
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Bibliography |
207 |
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Statistical Time Series Methods for Vibration Based Structural Health Monitoring |
216 |
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1 Introduction |
216 |
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2 The General Workframe |
219 |
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2.1 The Structural States and the Data Sets |
219 |
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2.2 The Baseline and Inspection Phases |
220 |
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2.3 Classes of Statistical Time Series SHM Methods |
222 |
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3 Statistical Time Series Models of the Structural Dynamics |
223 |
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3.1 Non-Parametric Models |
224 |
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3.2 Parametric Models |
225 |
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3.3 Identification of Time Series Models |
229 |
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4 Selected Non-Parametric Time Series SHM Methods |
231 |
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4.1 PSD Based Method |
232 |
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4.2 FRF Magnitude Based Method |
233 |
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5 Selected Parametric Time Series SHM Methods |
235 |
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5.1 Model Parameter Based Methods |
236 |
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5.2 Model Residual Based Methods |
238 |
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5.3 Functional Model (FM) Based SHM Methods |
245 |
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6 Application of the Methods to a Laboratory Truss Structure |
248 |
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6.1 The Laboratory Truss Structure and Problem Definition |
248 |
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6.2 Baseline Phase: Structural Identification |
250 |
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6.3 Inspection Phase: SHM via Selected Non-Parametric Methods |
252 |
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6.4 Inspection Phase: SHM via Selected Parametric Methods |
254 |
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6.5 Discussion |
258 |
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7 Concluding Remarks and Future Research |
261 |
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Bibliography |
263 |
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A Appendix: Central limit theorem and statistical distributions associated with the normal |
270 |
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A.1 The Central Limit Theorem (CLT) |
270 |
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A.2 The x² distribution |
270 |
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A.3 The Student’s t distribution |
271 |
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A.4 The Fisher’s F distribution |
271 |
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Fiber Optics Sensors |
272 |
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1 Introduction |
272 |
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2 Classification of Fiber Optic Sensors |
274 |
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2.1 Intensity-based sensors |
275 |
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2.2 Phase modulated optical fiber sensors, or Interferometers. |
277 |
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2.3 Wavelength based sensors, or Bragg gratings. |
278 |
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3 Fiber Bragg Gratings as Strain and Temperature Sensors |
281 |
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3.1 Response of the FBG to uniaxial uniform strain fields. |
282 |
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3.2 Sensitivity of the FBG to temperature. |
282 |
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3.3 Response of the FBG to non-uniform uniaxial strain field. |
283 |
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3.4 Response of the FBG to transverse stresses. |
285 |
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3.5 Commercial FBG interrogation systems. |
292 |
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4 Structures With Embedded Fiber Bragg Gratings |
292 |
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4.1 Orientation of the optical fiber optic respective to the reinforcement fibers. |
294 |
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4.2 Ingress/egress from the laminate. |
295 |
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5 Examples of Applications in Aeronautics and Civil Structures |
295 |
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5.1 Stiffened panels with embedded fiber Bragg gratings. |
296 |
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5.2 Concrete beam repair |
299 |
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6 Distributing Sensing |
301 |
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7 Applications of Distributed Sensing |
307 |
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8 Final Comments |
317 |
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Bibliography |
319 |
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Damage localisation using elastic waves propagation method. Experimental techniques. |
324 |
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1 Structural Health Monitoring based on elastic waves propagation |
324 |
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2 Elastic waves |
326 |
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3 Elastic wave generation and sensing |
334 |
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3.1 Elastic waves generation techniques |
334 |
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3.2 Elastic waves sensing techniques |
338 |
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4 Wave generation and sensing equipment |
345 |
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5 Transducer network configurations |
347 |
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6 Energy summing algorithm |
351 |
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6.1 Basis for numerical algorithm |
351 |
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6.2 Results |
355 |
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6.3 Summary |
361 |
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7 Beam forming algorithm |
363 |
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7.1 Basis for numerical algorithm |
363 |
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7.2 Results |
367 |
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7.3 Summary |
372 |
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Bibliography |
374 |
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Application for Wind Turbine Blades |
379 |
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1 A look at the Wind Energy Industry |
379 |
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2 Condition Monitoring of Wind Turbine Blades |
385 |
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3 Damage in Polymer Composite Materials |
396 |
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4 Structural Testing of Wind Turbine Blades |
412 |
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5 Future work |
424 |
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Bibliography |
432 |
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