Generation of cumulative second-harmonic ultrasonic guided waves with group velocity mismatching: Numerical analysis and experimental validation

Cumulative second harmonic of ultrasonic guided waves is considered to have great application potential in evaluating internal stress of structures. One difficulty with the application is the diversity and complexity of modal response to the stress change in waveguide. At present, there is a lack of relevant theoretical studies and experimental results to guide the applications. In this article, a method is proposed to characterize the amplitude change of cumulative second harmonic mode in a plate under stress through calculating the amplitude coefficient, which can be acquired based on mode shape analysis. The steel plate is taken as an example to demonstrate the analysis method. Experimental studies are presented with results consistent with the theoretical predictions. The results of this study indicate that the amplitudes of different cumulative second harmonic modes may increase or decrease monotonically with the change of stress. Therefore, when the phenomenon of modes mixing occurs in the waveguide, it is necessary to analyze and predict the amplitude of selected cumulative second harmonic mode with the change of stress in advance; otherwise, wrong results may be obtained. The method and conclusions proposed in this paper can also be applicable to waveguide of arbitrary cross-section and have universality.

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Review on second-harmonic generation of ultrasonic guided waves in solid media (I): Theoretical analyses

Chinese Physics B ◽

10.1088/1674-1056/26/11/114302 ◽

2017 ◽

Vol 26 (11) ◽

pp. 114302 ◽

Cited By ~ 7

Author(s):

Wei-Bin Li ◽

Ming-Xi Deng ◽

Yan-Xun Xiang

Keyword(s):

Second Harmonic Generation ◽

Harmonic Generation ◽

Guided Waves ◽

Second Harmonic ◽

Ultrasonic Guided Waves ◽

Solid Media ◽

Theoretical Analyses

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Effects of Adhesive Parameters on Dispersion Characteristics of Ultrasonic Guided Waves in Composite Pipes

Advances in Materials Science and Engineering ◽

10.1155/2019/2735328 ◽

2019 ◽

Vol 2019 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Juanjuan Li ◽

Yan Han

Keyword(s):

Group Velocity ◽

Guided Waves ◽

Velocity Dispersion ◽

Group Velocity Dispersion ◽

Adhesive Layer ◽

Dispersion Curves ◽

Ultrasonic Guided Waves ◽

Bonding Quality ◽

Mode Identification ◽

Composite Pipes

The aim of the investigation presented here was to understand how the viscosity parameters of an adhesive layer affect group velocity and attenuation of the double-layer adhered pipe. Various parameter combinations (attenuation of longitudinal wave and shear wave, pαL and qαT; thickness, d; and density, nρ) were utilized in order to generate different uncured degrees of the adhesive layer. In the frequency range 0∼500 kHz, the group velocity dispersion curves and attenuation dispersion curves were obtained from these models. Then, the group velocity and attenuation of the two commonly used modes, L0,2 and T0,1, were compared and analyzed. The results have shown that it is important to remark that little effect on group velocity was caused, and significant linear increases of attenuation occur with increase in q, d, and n. However, variable p had little effect on attenuation; more modes emerged when d increased or n decreased, causing difficulties on mode identification and signal processing. The numerical results provided a useful way to evaluate bonding quality by measuring the group velocity and attenuation in the pipelines.

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