1 Introduction 1
1.1 Overview 1
1.2 Concept of Smart Systems/Structures for SHM 5
1.3 Smart Materials 6
1.4 Piezoelectricity and Piezoelectric Materials 7
References 14
2 Electro-Mechanical Impedance Technique 17
2.1 Introduction 17
2.2 Mechanical Impedance of Structures 18
2.3 Impedance Modeling for EMI Technique 21
2.4 Mechanical Impedance of PZT Patches 27
2.5 PZT-Structure Interaction 29
2.6 Practical Aspects of EMI Technique 35
2.7 Signal Processing Techniques and Conventional Damage Quantification 39
2.8 Major Technological Developments During the Last One and a Half Decades 41
2.9 Advantages of EMI Technique 46
2.10 Limitations of EMI Technique 47
References 47
Exercise 2.1 50
3 Impedance Models for Structural Health Monitoring Using Piezo-Impedance Transducers 53
3.1 Introduction 53
3.2 Early PZT-Structure Interaction Models 53
3.3 2D Effective Mechanical Impedance 56
3.4 2D Formulation Based on Effective Impedance 58
3.5 Experimental Verification 62
3.5.1 Details of Experimental Set-up 62
3.5.2 Determination of Structural EDP Impedance by FEM 63
3.5.3 Modeling of Structural Damping 67
3.5.4 Wavelength Analysis and Convergence Test 67
3.5.5 Comparison between Theoretical and Experimental Signatures 69
3.6 Refining the 2D Impedance Model 70
3.7 3D Interaction of PZT Transducer with Host Structure 77
3.7.1 Necessity of3D Formulation 77
3.7.2 Issues in ID and 2D Impedance Models 77
3.7.3 Issues to Consider in 3D Impedance Model 78
3.8 3D Model in Presence of Thick Adhesive Bonding 81
3.8.1 Impedance Formulation 81
3.8.2 Stress-Strain Relationship of PZT Patch Subjected to 3D Loading 85
3.8.3 3D Differential Equations 86
3.8.4 Solution to 3D Differential Equations 87
3.8.5 Active Part of Solution 89
3.8.6 Stress-Strain Relationships in Presence of Electric Fields 90
3.8.7 Formulation of Structural Responses and Impedances 91
3.8.8 EM Admittance Formulation for M-Functioning PZT Patches 96
3.8.9 Modifications of Linear Impedance Formulations for Case Studies 98
3.8.10 Results and Discussions 104
3.9 FE Modeling of EMI Technique Using Coupled Field Element 106
3.9.1 Review on FE Modeling of PZT-Structure Interaction 106
3.9.2 Inclusion of Induced Strain Actuator in FE Model 108
3.9.3 Comparison of FE Model with Existing Impedance-Based Analytical Model and Experimental Tests 109
3.9.4 FE Modeling of PZT-Structure Interaction 115
References 124
Exercise 3.1 126
Exercise 3.2 127
Exercise 3.3 128
4 Damage Quantification Using EMI Technique 129
4.1 Extraction of Structural Mechanical Impedance from Admittance Signatures 129
4.2 System Parameter Identification from Extracted Impedance Spectra 132
4.3 Damage Diagnosis in Aerospace and Mechanical Systems 137
4.4 Extension to Damage Diagnosis in Civil-Structural Systems 144
4.5 Identification of Higher Modal Frequencies from Conductance Signatures 146
4.6 Numerical Example 150
4.7 Experimental Verifieation 155
4.7.1 Damage Location Identification 158
4.7.2 Effect of Number of Sensitive Modes 159
4.7.3 Effect of Frequency Range 161
4.8 Advantages of Modal Approach 163
4.9 Limitations and Concerns of Modal Approach 163
4.10 Damage Identification Using EMI and Evolutionary Programming 164
4.11 EMI of PZT Transducers 165
4.12 Mechanical Impedance of Damaged Structure 167
4.13 Damage Identification Method 173
4.13.1 EP Algorithm 173
4.13.2 Fitness Function 174
4.14 Experimental Set-up 175
4.15 Experimental Results and Numerical Predictions 177
4.15.1 Damage Identification Results 181
4.15.2 Summary 184
References 184
Exercise 4.1 186
Exercise 4.2 186
5 Strength and Damage Assessment of Concrete 187
5.1 Introduction 187
5.2 Conventional NDE Techniques for Concrete 187
5.3 Concrete Strength Evaluation Using EMI Technique 190
5.4 Extraction of Damage-Sensitive Concrete Parameters from Admittance Signatures 194
5.5 Monitoring Concrete Curing Using Extracted Impedance Parameters 198
5.6 Establishment of Impedance-Based Damage Model for Concrete 201
5.6.1 Definition of Damage Variable 201
5.6.2 Damage Variable Based on the Theory of Fuzzy Sets 204
5.6.3 Fuzzy Probabilistic Damage Calibration of Piezo-Impedance Transducers 207
5.7 Embedded PZT Patches and Issues Involved 210
5.8 Experimental Set-up 211
5.8.1 Methods to Fabricate Embeddable PZT 211
5.8.2 Fabrication of Robust Embeddable PZT Patch 213
5.9 Efficiency of Embedded PZT 216
5.9.1 Comparison Test 216
5.9.2 Monitoring Test 217
5.10 Damage Analysis Using Statistical Method 218
References 220
6 Integration of EMI Technique with Global Vibration Techniques 223
6.1 Introduction 223
6.2 Piezoelectric Materials as Dynamic Strain Sensors 224
6.3 Determination of Strain Mode Shapes Using Surface-Bonded PZT Patches 226
6.4 Identification and Localization of Incipient Damage 230
6.5 Localization of Moderate and Severe Damages Using Global Vibration Techniques 234
6.5.1 For 1D Structures(Beams) 234
6.5.2 For 2D Structures(Plates) 236
6.6 Severity of Damage 239
References 243
7 Sensing Region,Load Monitoring and Practical Issues 245
7.1 Sensing Region of PZT Patches 245
7.1.1 Introduction 245
7.1.2 Theoretical Modeling 246
7.1.3 Experimental Verification 258
7.1.4 Results and Discussions 259
7.1.5 Summary 264
7.2 PZT Patches for Load Monitoring 265
7.2.1 Introduction 265
7.2.2 Effect of Stress in Structure 265
7.2.3 Influence of Applied Load on EM Admittance Signatures 266
7.2.4 Experimental Investigations and Discussions 267
7.2.5 Efficiency of EM Admittance Signatures Using Statistical Index 271
7.2.6 Summary 275
7.3 Practical Issues Related to Application of EMI Technique in SHM 275
7.3.1 Introduction 275
7.3.2 Consistency of Admittance Signatures Acquired from PZT Patch 276
7.3.3 Effects of Bonding Layer and Temperature 282
7.3.4 Differentiating Temperature-Induced and Damage-Induced Signature Deviations 291
7.3.5 Differentiating Damage in Host Structure and in PZT Patch 293
7.3.6 Summary 294
References 295
8 Smart Beams:A Semi-Analytical Method 299
8.1 Introduction 299
8.2 Analysis of a Column Coupled with Distributed Piezoelectric Actuator 302
8.2.1 Motion Equations 303
8.2.2 Analytical Solutions for Displacement Feedback Control 306
8.2.3 Semi-Analytical Solutions for Velocity Feedback Control 312
8.2.4 Effects of Feedback Strategies on Motion Equations 317
8.3 Numerical simulations 318
8.3.1 Numerical Results for Displacement Feedback Control 319
8.3.2 Numerical Results for Velocity Feedback Control 325
8.4 Conclusions and Recommendations 329
8.4.1 Conclusions 329
8.4.2 Recommendations 329
References 330
9 Smart Plates and Shells 333
9.1 Optimal Vibration Control using Genetic Algorithms 333
9.1.1 Introduction 333
9.1.2 Sensing and Actuating Equations 335
9.1.3 Energy-Based Approach for Integrated Optimal Design 343
9.1.4 General Formulation and Modified Real-Encoded GA 345
9.1.5 Numerical Examples 348
9.2 Optimal Excitation of Piezoelectric Plates and Shells 362
9.2.1 Introduction 362
9.2.2 Piezoelectric Actuated Plates 363
9.2.3 Piezoelectric Actuated Cylindrical Shell 370
9.2.4 Optimal Placement of PZT Actuator on Plate 374
9.2.5 Optimal Placement of PZT Actuator on Shell 387
9.2.6 Discussions 389
9.2.7 Summary 391
References 392
10 Cylindrical Shells with Piezoelectric Shear Actuators 395
10.1 Introduction 395
10.2 Governing Equations 397
10.3 Non-Damping Vibration of Simply Supported Shell 399
10.4 Active Vibration Control of Cylindrical Shell with PSAs 401
10.5 Numerical Results and Discussions 402
10.5.1 Steady-State Response Analysis 403
10.5.2 Active Vibration Control 407
10.6 Summary 410
References 410
11 Fiber Bragg Grating 413
11.1 Introduction 413
11.2 History of FBG 414
11.3 Fabrication of FBG 415
11.4 Optical Properties of Grating 417
11.5 Thermal Properties of FBG 420
11.6 Mechanical Properties of FBG 421
11.7 Maximun Reflectivity of Bragg Grating 422
11.8 Full Width at Half Maximum 423
11.9 FBG Sensors 424
11.9.1 Direct Sensing Using FBG 424
11.9.2 Indirect Sensing by Embedded FBG 425
11.10 FBG-Based Pressure/Strain Sensor 427
11.11 FBG-Based Shear Force Sensor 428
References 435
12 Applications of Fiber Bragg Grating Sensors 441
12.1 Introduction 441
12.2 Pressure Monitoring at Foot Sole of Diabetic Patients 441
12.3 Pressure and Temperature Monitoring in a Dental Splint 445
12.3.1 Structure of FBG-Based Splint Sensor 446
12.3.2 Experimental Results and Discussions 447
12.4 Monitoring Civil Structures 449
12.4.1 Sensing Approach 449
12.4.2 Symmetrically Bonded FBG Sensor Arrays on Rebars 449
12.4.3 Contact Force Measurement at Beam-Column Joint 458
12.5 Multi-Component Force Measurement 460
12.5.1 Basic Concept 461
12.5.2 Two-Component Force Measurement 462
12.5.3 2D Force Measurement 466
12.5.4 3D Force Measurement 467
12.6 Simultaneous Measurement of Pressure and Temperature 472
12.6.1 Sensor Configuration and Working Principle 472
12.6.2 Sensor Fabrication and Experimental Procedure 475
12.7 Summary 477
References 478
13 Monitoring of Rocks and Underground Structures Using PZT and FBG Sensors 481
13.1 Introduction 481
13.2 Conventional Versus Smart Material Based Sensor Systems for LHR and SHM of Underground Structures 482
13.3 Experimental Investigations on Rocks 483
13.4 LHR by ESG and FBG Sensors 485
13.4.1 Specimen 1 485
13.4.2 Specimen 2 487
13.5 SHM by PZT Transducers 489
13.5.1 Specimen 1 489
13.5.2 Specimen 2 491
13.5.3 Specimen 3 492
13.5.4 Extraction of Structural Mechanical Impedance 493
13.5.5 Calibration of Extracted Parameters for Damage Quantification 494
13.6 Robustness of PZT Transducers and FBG-Based Strain Gauges 497
13.7 Potential Applications of Smart Sensors on Rock Structures 497
References 499
14 Ionic Polymer-Metal Composite and its Actuation Characteristics 501
14.1 Introduction 501
14.1.1 History and Characterizations 501
14.1.2 Experimental Study and Physical Modeling 503
14.1.3 Implemented and Potential Applications 507
14.2 Bending Moment Capacity of IPMC 507
14.2.1 Charge Redistribution 507
14.2.2 Bending Moment 512
14.3 Validation and Discussions 520
14.4 Frequency Dependent Characteristics 525
14.5 Summary 529
References 530
15 IPMC-Based Biomedical Applications 533
15.1 Introduction 533
15.2 IPMC Beam on Human Tissues 534
15.2.1 Modeling of IPMC Beam on Human Tissues 534
15.2.2 Illustrative Examples and Discussions 536
15.3 IPMC Ring with Elastic Medium 543
15.3.1 Problem Formulation 543
15.3.2 Displacement Solutions 546
15.3.3 Illustrative Examples 548
15.4 IPMC Shell with Flowing Fluid 554
15.4.1 Problem Formulation 554
15.4.2 Wave Propagation Solutions 559
15.4.3 Illustrative Example and Discussion 563
15.5 Summary 565
References 567
16 Bone Characterization Using Piezo-Transducers as Bio-Medical Sensors 569
16.1 Introduction 569
16.2 Monitoring Changes in Bone Density 572
16.3 Monitoring Healing Process in Bones 575
16.4 FE Simulation of EMI Technique on Bones 577
References 580
17 Future of Smart Materials 583
17.1 Past and Future Developments of IPMC 583
17.2 PZT/MFC in Energy Harvesting 585
17.2.1 Current Research in Energy Harvesting using Piezoelectric Materials 585
17.2.2 Main Concerns for Future Practical Applications 587
17.3 Futuristic Applications of Smart Materials 591
References 592
Appendix 595
Index 613