Measurement of Nonlinear Ultrasonic Characteristics (eBook)

Preface 6
Contents 8
1 Overview—Nonlinear Ultrasonic Characteristics 12
References 16
Measurements of Nonlinear Ultrasonic Characteristics Related with Material Elastic Nonlinearity 17
2 Measurement of Nonlinear Ultrasonic Parameters from Higher Harmonics 18
2.1 Higher Harmonic Generation 21
2.2 Nonlinear Ultrasonic Parameters 24
2.3 Measurement of Nonlinear Ultrasonic Parameters 26
2.3.1 Absolute Nonlinear Ultrasonic Parameter (Piezoelectric Method) 26
2.3.2 Relative Nonlinear Ultrasonic Parameter 31
2.3.3 Estimation of Absolute Nonlinear Ultrasonic Parameter by Measurement of Relative Nonlinear Ultrasonic Parameters 33
2.3.4 Measurement Reliability Test 39
2.4 Factors Affecting Measurement Reliability 42
2.4.1 Uncertain Initial Harmonics 43
2.4.2 Couplant Layer 44
2.4.3 Analog-to-Digital Conversion 47
2.4.4 Digital Signal Processing 53
2.5 Application to Assess Thermal Aging in Al Alloy 56
2.6 Associated Methodologies 60
2.6.1 Phase Inversion Technique 60
2.6.2 Pulse-Echo 63
2.6.3 V-Scan 63
2.6.4 Laser-Ultrasonic Surface Acoustic Waves 64
References 66
3 Measurement of Nonlinear Guided Waves 70
3.1 Introduction 71
3.2 Background 72
3.2.1 Linear Guided Wave Propagation 73
3.2.2 Brief History of Nonlinear Guided Waves 74
3.3 Primary Wave Selection for Secondary Wave Generation 76
3.3.1 Basic Principles 77
3.3.2 Theoretical Formulation 77
3.3.3 Self-interaction 82
3.3.4 Mutual Interaction in Plate 87
3.4 Actuation of Primary Waves and Sensing of Secondary Waves 90
3.4.1 Actuation of Lamb Waves 91
3.4.2 Actuation of SH Waves 93
3.4.3 Sensing 94
3.4.4 Effects of Diffraction 94
3.5 Instrumentation and Signal Processing 95
3.5.1 Instrumentation 95
3.5.2 Signal Processing 97
3.6 Measurement Considerations 98
3.6.1 Measurement System Nonlinearities 98
3.6.2 Material Nonlinearities 99
3.6.3 Measuring Progressive Degradation 100
3.7 Closing Comments 113
References 114
Measurements of Nonlinear Ultrasonic Characteristics Related with Contact Acoustic Nonlinearity 118
4 Nonlinear Acoustic Measurements for NDE Applications: Waves Versus Vibrations 119
4.1 Introduction 119
4.2 Fundamental Effect in Nonlinear Acoustics: Higher Harmonic Generation for Longitudinal Acoustic Waves 121
4.2.1 Experimental Validation of Higher Harmonic Characteristics 123
4.3 Nonlinear SAW: Theory 128
4.3.1 Nonlinear Surface Waves: Experimental 130
4.4 Localized Nonlinearity of a Non-bonded Interface 133
4.5 Localized Nonlinearity for Monitoring of Bonding Quality 137
4.5.1 Methodology 138
4.5.2 Specimens 140
4.5.3 Measurement Results 140
4.5.4 Evaluation of Bonding Quality in Realistic Aviation Components 145
4.6 Local Defect Resonance (LDR) and Localized Nonlinearity 147
4.7 Enhancement of Nonlinearity in Various Types of Nonlinear Resonances 152
4.7.1 Super-Harmonic Resonance 152
4.7.2 Combination Frequency Resonance 154
4.7.3 Subharmonic and Parametric Resonances 155
4.8 Linear and Nonlinear LDR for Non-contact Diagnostic Imaging of Defects 159
4.8.1 Experimental Methodology 160
4.8.2 Noncontact LDR Imaging Results 161
4.8.3 Nonlinear LDR Diagnostic Imaging 164
4.9 Conclusions 167
References 170
5 Nonlinear Ultrasonic Phased Array for Measurement of Closed-Crack Depth 173
5.1 Introduction 173
5.2 Subharmonics 180
5.2.1 Principles 181
5.2.2 Experimental Conditions 185
5.2.3 Imaging Results 190
5.3 Parallel and Sequential Transmission 197
5.3.1 Principles 197
5.3.2 Experimental Conditions 203
5.3.3 Imaging Results 205
5.4 All-Elements, Odd-Elements, and Even-Elements Transmission 211
5.4.1 Principles 211
5.4.2 Experimental Conditions 215
5.4.3 Imaging Results 219
5.5 Utilization of Thermal Stress 224
5.5.1 Principles 224
5.5.2 Experimental Conditions 227
5.5.3 Imaging Results 230
5.6 Conclusions 237
References 238
6 Nonlinear Frequency-Mixing Photoacoustic Characterisation of a Crack 243
6.1 Introduction to Nonlinear Photoacoustics 244
6.1.1 An Overview of a Few Non-destructive Methods Combining Laser Optics with Nonlinear Acoustics 245
6.1.2 Generation of Thermoelastic Stresses and Acoustic Waves by Modulation of Continuous Wave Laser Radiation 246
6.1.3 Influence of Stationary Laser Heating on a Crack 249
6.2 Nonlinear Frequency-Mixing Photoacoustic Method for Crack Detection 254
6.2.1 Experimental Setup 254
6.2.2 Principle of the Method 255
6.2.3 One Dimensional Imaging for Crack Localisation 258
6.2.4 Two Dimensional Imaging of a Crack 260
6.2.5 Spatial Resolution of the Crack Images 263
6.3 Towards Quantitative Evaluation of Local Crack Parameters 268
6.3.1 Theoretical Model 269
6.3.2 Evolution of the Nonlinear Sidelobes Amplitude with the Loading 276
6.3.3 Extraction of Crack Parameters 280
6.4 Conclusion 283
References 285
Index 290