Abstract (Chinese) i
Abstract (English) iii
Acknowledgements vi
Contents vii
List of Tables ix
List of Figures x
Chapter 1: Introduction 1
1.1. Crack inspection 1
1.2. Field mapping of EC robes 4
1.3. Research motivation 9
1.4. Outline of approach and thesis 11
Chapter 2: Differential Formulation of the Governing Equations 13
2.1. Basic theoretical background of photoinductive imaging 13
2.2. Equations of heat transfer by conduction 15
2.3. Equations of quasi-static electromagnetic field 18
2.4. Solution of partial differential equations 22
2.4.1. Coefficient form 22
2.4.2. General form 23
2.4.3. Weak form 25
2.5. Formulation implementation by FEM 27
2.5.1. Heat transfer 27
2.5.2. Quasi-static electromagnetic field 29
Chapter 3: The Processing of FEM Simulation and Analysis 31
3.1. Brief overview of COMSOL 33
3.1.1. Module selection 33
3.1.2. Solver selection 34
3.2. The 2-D model the photoinductive imaging method 35
3.2.1. Crack detection 35
3.2.2. Field mapping of EC probes 39
3.3. The programming process of the scanning mode for the PI method 41
Chapter 4: Simulation Results and Analysis for Crack Detection 45
4.1. The 2-D actual size model of the PI method 45
4.2. Comparison the PI and ECT methods in the 2-D simplified model 48
4.2.1. Spatial resolution 49
4.2.2. Excitation current frequency 50
4.2.3. Laser point temperature for PI method 53
4.2.4. Characterizing different length notches 55
4.2.5. Lift-off distance 57
Chapter 5: Simulation Results and Analysis for Field Mapping of EC Probes
60
5.1. EC probes with tilted coils in the 2-D simplified model 60
5.2. Effects of the excited frequency 63
5.3. Effects of electrical and thermal properties of thin metal film 65
5.3.1. Electrical properties of the thin film 65
5.3.2. Thermal properties of the thin film 69
5.4. Effects of thin film materials 73
5.5. Effects of thicknesses of the thin film 75
5.6. Comparison of field mapping resolution 77
5.7. Comparison of simplified structural coil and actual structural coil 79
5.8. Comparison of 2-D raster scanning results 79
Chapter 6: Conclusions and Future Work 83
6.1. Crack inspection 83
6.2. Field mapping of EC probes 83
6.3. Future Work 84
Appendix 1: Weak Form of Quasi-Static Electromagnetic Field 86
Appendix 2: Thesis Defense 88
References 92
Publication List 97
Vita 98
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