scholarly journals Air-coupled Lamb Waves Propagation Characteristics and Defect Detection in Monocrystalline Silicon

2015 ◽  
Vol 51 (12) ◽  
pp. 1 ◽  
Author(s):  
Cunfu HE
Keyword(s):  
Defect Detection ◽  
Lamb Waves ◽  
Monocrystalline Silicon ◽  
Propagation Characteristics ◽  
Waves Propagation

Warped-wigner-hough transformation of lamb waves for automatic defect detection

2011 ◽  
Author(s):  
Alessandro Perelli ◽  
Luca De Marchi ◽  
Emanuele Baravelli ◽  
Alessandro Marzani ◽  
Nicolo Speciale
Keyword(s):  
Defect Detection ◽  
Lamb Waves ◽  
Hough Transformation

scholarly journals Delamination Localization in Sandwich Skin Using Lamb Waves by Finite Element Method

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Salah Nissabouri ◽  
Mhammed El allami ◽  
El Hassan Boutyour ◽  
Ahmed Errkik
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Lamb Waves ◽  
Arrival Times ◽  
Localization Method ◽  
Waves Propagation ◽  
Signal Changes ◽  
2D Fft ◽  
Mode A ◽  
Element Method

In this work we model by finite element method (FEM) the Lamb waves’ propagation and their interactions with symmetric and asymmetric delamination in sandwich skin. The simulations were carried out using ABAQUS CAE by exciting the fundamental A0 Lamb mode in the frequency 300 kHz. The delamination was then estimated by analysing the signal picked up at two sensors using two technics: Two-Dimensional Fast Fourier Transform (2D-FFT) to identify the propagating and converted modes, and wavelet transform (WT) to measure the arrival times. The results showed that the mode A0 is sensible to symmetric and asymmetric delamination. Besides, based on signal changes with the delamination edges, a localization method is proposed to estimate the position and the length of the delamination. In the last section an experimental FEM verification is provided to validate the proposed method.

scholarly journals Leaky Lamb Wave Radiation from a Waveguide Plate with Finite Width

2020 ◽  
Vol 10 (22) ◽  
pp. 8104
Author(s):  
Sang-Jin Park ◽  
Hoe-Woong Kim ◽  
Young-Sang Joo
Keyword(s):  
Lamb Wave ◽  
Lamb Waves ◽  
Wave Mode ◽  
Wave Radiation ◽  
Finite Width ◽  
Propagation Characteristics ◽  
Radiation Characteristics ◽  
Radiation Beam ◽  
Leaky Lamb Wave ◽  
Waveguide Sensor

In this paper, leaky Lamb wave radiation from a waveguide plate with finite width is investigated to gain a basic understanding of the radiation characteristics of the plate-type waveguide sensor. Although the leaky Lamb wave behavior has already been theoretically revealed, most studies have only dealt with two dimensional radiations of a single leaky Lamb wave mode in an infinitely wide plate, and the effect of the width modes (that are additionally formed by the lateral sides of the plate) on leaky Lamb wave radiation has not been fully addressed. This work aimed to explain the propagation behavior and characteristics of the Lamb waves induced by the existence of the width modes and to reveal their effects on leaky Lamb wave radiation for the performance improvement of the waveguide sensor. To investigate the effect of the width modes in a waveguide plate with finite width, propagation characteristics of the Lamb waves were analyzed by the semi-analytical finite element (SAFE) method. Then, the Lamb wave radiation was computationally modeled on the basis of the analyzed propagation characteristics and was also experimentally measured for comparison. From the modeled and measured results of the leaky radiation beam, it was found that the width modes could affect leaky Lamb wave radiation with the mode superposition and radiation characteristics were significantly changed depending on the wave phase of the superposed modes on the radiation surface.

Modelling of Lamb Waves Propagation in Orthotropic Plate

2020 ◽  
pp. 315-340
Author(s):  
Salah Nissabouri ◽  
Mhammed El Allami ◽  
El Hassan Boutyour
Keyword(s):  
Finite Element Method ◽  
Orthotropic Plate ◽  
Lamb Waves ◽  
Two Dimensional ◽  
Arrival Times ◽  
Localization Method ◽  
Waves Propagation ◽  
Signal Changes ◽  
2D Fft ◽  
Lamb Mode

In this chapter, we model by Finite Element Method (FEM) the Lamb waves' propagation and their interactions with symmetric and asymmetric delamination in sandwich skin. Firstly, a theoretical model is established to obtain the equation of lamb modes propagation. Secondly, dispersion curves are plotted using Matlab program for the laminate [0]4. The simulations were then carried out using ABAQUS CAE by exciting the fundamental A0 Lamb mode in the frequency 300 kHz. The delamination was then estimated by analyzing the signal picked up at two sensors using two techniques: Two Dimensional Fast Fourier Transform (2D-FFT) to identify the propagating and converted modes, and Wavelet Transform (WT) to measure the arrival times. The results showed that the mode A0 is sensible to symmetric and asymmetric delamination. Besides, based on signal changes with the delamination edges, a localization method is proposed to estimate the position and the length of the delamination. In the last section, an experimental FEM verification is provided to validate the proposed method.

Coupled Lamb waves propagation along the direction of non-principal symmetry axes in pre-stressed anisotropic composite lamina

Wave Motion ◽  
2020 ◽  
Vol 97 ◽  
pp. 102591
Author(s):  
Hongye Liu ◽  
Shen Liu ◽  
Xin Chen ◽  
Yan Lyu ◽  
Zenghua Liu
Keyword(s):  
Lamb Waves ◽  
Anisotropic Composite ◽  
Waves Propagation

scholarly journals Defects Detection and Localization in Underwater Plates Using Laser Laterally Generated Pure Non-Dispersive S0 Mode

2019 ◽  
Vol 9 (3) ◽  
pp. 459 ◽  
Author(s):  
Qingnan Xie ◽  
Chenyin Ni ◽  
Zhonghua Shen
Keyword(s):  
Defect Detection ◽  
Lamb Waves ◽  
Mode Conversion ◽  
High Sensitivity ◽  
Laser Source ◽  
Dispersion Characteristics ◽  
High Attenuation ◽  
Corrosion Defects ◽  
Detection And Localization ◽  
Lateral Excitation

When working in humid environments, corrosion defects are easily produced in metallic plates. For defect detection in underwater plates, symmetric modes of Lamb waves are widely used because of their characteristics including long propagating distance and high sensitivity to defects. In this study, we extend our previous work by applying the laser laterally generated S0 mode to detection and localization of defects represented by artificial notches in an aluminum plate immersed in water. Pure non-dispersive S0 mode is generated in an underwater plate by lateral laser source irradiation and its fd (frequency·thickness) range is selected by theoretical calculation. Using this lateral excitation, the S0 mode is enhanced; meanwhile, the A0 mode is effectively suppressed. The mode-converted A0 mode from the incident S0 mode is used to detect and localize the defect. The results reveal a significantly improved capability to detect defects in an underwater plate using the laser laterally generated S0 mode, while that using A0 is limited due to its high attenuation. Furthermore, owing to the long propagating distance and the non-dispersion characteristics of the S0 generated by the lateral laser source, multiple defects can also be detected and localized according to the mode conversion at the defects.

scholarly journals Experimental Study of Lamb Waves Propagation inside an Impact Damage in the Size of the Used Wavelength

2020 ◽  
Vol 56 (2) ◽  
pp. 141-150
Author(s):  
S. Taleb ◽  
L. Rittmeier ◽  
M. Sinapius ◽  
F. Boubenider ◽  
D. Schmidt
Keyword(s):  
Experimental Study ◽  
Lamb Waves ◽  
Impact Damage ◽  
Waves Propagation

Impact of Rough Wall Surface on Electromagnetic Wave Propagation Characteristics in Mine Tunnels

2011 ◽  
Vol 301-303 ◽  
pp. 1417-1421
Author(s):  
Shan Hua Yao ◽  
Xian Liang Wu
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Wave ◽  
Coal Mine ◽  
Electromagnetic Waves ◽  
Electromagnetic Wave Propagation ◽  
Rough Wall ◽  
Wall Surface ◽  
Propagation Characteristics ◽  
Waves Propagation ◽  
Mine Tunnels

In this paper ,the mine tunnels is regard as wave-guide which contains kinds of un-beneficial medium, we have study the formulas of electromagnetic waves propagation attenuation and roughness attenuation, the relations between propagation attenuation and roughness and frequency were simulated. The results show that the influence of propagation attenuation in lower frequency is more obvious, and roughness attenuation is increased rapidly as roughness of coal mine tunnels increasing. But tilted attenuation is stronger than roughness attenuation as propagation frequency increasing.

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