Dual Element Transducer Approach for Second Harmonic Generation and Material Nonlinearity Measurement of Solids in the Pulse-Echo Method

2020 ◽  
Vol 39 (3) ◽  
Author(s):  
Sungjong Cho ◽  
Hyunjo Jeong ◽  
Shuzeng Zhang ◽  
Xiongbing Li
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Material Nonlinearity ◽  
Pulse Echo ◽  
Pulse Echo Method

scholarly journals Second-harmonic generation in focused beam fields of phased-array transducers in a nonlinear solid with a stress-free boundary

2019 ◽  
Vol 1 (2) ◽  
pp. 117-125
Author(s):  
Hyunjo Jeong ◽  
Shu-zeng Zhang ◽  
Xiong-bing Li
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Phase Difference ◽  
Phased Array ◽  
Second Harmonic ◽  
Free Boundaries ◽  
Harmonic Components ◽  
Focused Beams ◽  
Pulse Echo ◽  
Focused Beam

Abstract In nonlinear acoustic harmonic generation in solids with stress-free boundaries, such a boundary is known to destructively change the second harmonic generation, and the pulse-echo method is not practically applicable. Focused beams have often been used for fluid nonlinearity and biomechanical imaging in pulse-echo test setups. This paper considers the focused beam fields of linear phased-array transducers to ensure that pulse-echo harmonic generation can be applied to solids with stress-free boundaries. The fundamental and second-harmonic beam fields that are focused and reflected at the stress-free and rigid boundaries are calculated and their properties are investigated in terms of the received average fields. The phase difference between the two second-harmonic components after reflection from the boundary—that is, the reflected and the newly generated second harmonic—is emphasized. The phase difference is used to explain the improved and accumulated second harmonic observed in the simulation results.

Cumulative Second Harmonic Generation of Ultrasonic Guided Waves Propagation in Tube-Like Structure

2016 ◽  
Vol 24 (03) ◽  
pp. 1650011 ◽  
Author(s):  
Weibin Li ◽  
Mingxi Deng ◽  
Younho Cho
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Polyvinylidene Fluoride ◽  
Guided Waves ◽  
Second Harmonic ◽  
Cumulative Effect ◽  
Guided Wave ◽  
Ultrasonic Waves ◽  
Material Nonlinearity ◽  
Fundamental Wave

Second harmonic generation of ultrasonic waves propagating in unbounded media and plate-like structure has been vigorously studied for tracking material nonlinearity, however, second harmonic guided wave propagation in tube-like structures is rarely studied. Considering that second harmonics can provide sensitive information for structural health condition, this paper aims to study the second harmonic generation of guided waves in metallic tube-like structures with weakly nonlinearity. Perturbation method and modal analysis approach are used to analyze the acoustic field of second harmonic solutions. The conditions for generating second harmonics with cumulative effect are provided in present investigation. Flexible polyvinylidene fluoride comb transducers are used to measure fundamental wave modes and second harmonic ones. The work experimentally verifies that the second harmonics of guided waves in pipe have a cumulative effect with propagation distance. The proposed procedure of this work can be applied to detect material nonlinearity due to damage mechanism in tube-like structure.

Test of directional photoionisation models of second harmonic generation in optical fibres

1992 ◽  
Vol 139 (2) ◽  
pp. 133 ◽  
Author(s):  
N.M. Lawandy ◽  
T.J. Driscoll ◽  
C.L. Adler ◽  
N.M. Lawandy
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Optical Fibres
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