Wave-Mode Coordinates and Scattering Matrices for Wave Propagation.

1986 ◽  
Author(s):  
James H. Williams ◽  
Nagem Jr. ◽  
Yeung Raymond J. ◽  
Hubert K.
Keyword(s):  
Wave Propagation ◽  
Wave Mode ◽  
Scattering Matrices

scholarly journals Wave Propagation Analysis in Composite Laminates Containing a Delamination Using a Three-Dimensional Spectral Element Method

2012 ◽  
Vol 2012 ◽  
pp. 1-19 ◽  
Author(s):  
Fucai Li ◽  
Haikuo Peng ◽  
Xuewei Sun ◽  
Jinfu Wang ◽  
Guang Meng
Keyword(s):  
Wave Propagation ◽  
Lamb Wave ◽  
Composite Laminates ◽  
Composite Structures ◽  
Spectral Element Method ◽  
Three Dimensional ◽  
Spectral Element ◽  
Wave Mode ◽  
Diagonal Form ◽  
Element Method

A three-dimensional spectral element method (SEM) was developed for analysis of Lamb wave propagation in composite laminates containing a delamination. SEM is more efficient in simulating wave propagation in structures than conventional finite element method (FEM) because of its unique diagonal form of the mass matrix. Three types of composite laminates, namely, unidirectional-ply laminates, cross-ply laminates, and angle-ply laminates are modeled using three-dimensional spectral finite elements. Wave propagation characteristics in intact composite laminates are investigated, and the effectiveness of the method is validated by comparison of the simulation results with analytical solutions based on transfer matrix method. Different Lamb wave mode interactions with delamination are evaluated, and it is demonstrated that symmetric Lamb wave mode may be insensitive to delamination at certain interfaces of laminates while the antisymmetric mode is more suited for identification of delamination in composite structures.

Wave Propagation in the Linear Theory of Elastic Shells

1976 ◽  
Vol 43 (2) ◽  
pp. 281-285 ◽  
Author(s):  
H. Cohen
Keyword(s):  
Wave Propagation ◽  
Circular Cylinder ◽  
Linear Theory ◽  
Wave Mode ◽  
Mode Shapes ◽  
Elastic Shells ◽  
Special Cases ◽  
Cosserat Surface ◽  
Singular Wave ◽  
The Right

The problem of wave propagation in elastic shells within the framework of a linear theory of a Cosserat surface is treated using the method of singular wave curves. The equations for determining the speeds of propagation and their associated wave mode shapes are obtained in a form involving the speeds of propagation in Cosserat plates and the curvature of the shell. A number of special cases in which the speeds and mode shapes simplify are considered. In particular, these special cases are shown to include as examples, certain systems of waves in elastic shells whose middle surfaces are the surface of revolution, the circular cylinder, the sphere, and the right helicoid.

WAVE PROPAGATION IN LIPOSOMES

2013 ◽  
Vol 13 (01) ◽  
pp. 1350015
Author(s):  
KE DONG ◽  
GUOXING LU
Keyword(s):  
Wave Propagation ◽  
Wave Speed ◽  
Critical Frequency ◽  
Low Frequency ◽  
Wave Mode ◽  
Frequency Region ◽  
Wave Number ◽  
Rotary Inertia ◽  
High Frequency Region ◽  
Wave Modes

The general behavior of wave propagation in liposomes, including the effect of rotary inertia, is examined in this paper, based on a continuum cylindrical shell model. The disperse curves are obtained by solving an eigenvalue problem. The characteristics of wave propagation in liposomes are described using numerical examples. The results show that wave propagation in liposomes has a threshold critical frequency beyond which the wave speed drops dramatically and also a cut-off critical frequency below which the corresponding wave mode does not appear. The torsional wave speed is obtained for the symmetrical circumferential mode n = 0. The cut-off or threshold critical frequency decreases with the increase of liposomal radius, but the effect of radius on wave speed is not significant in the frequency region higher than the critical frequency. On the other hand, the wave number n leads to an increase in the critical frequency. For the first and second wave modes, the wave speed is insensitive to the wave number when the frequency is greater than the critical frequency. For the third wave mode in the low frequency region, the wave number leads to an increase in the wave speed. The rotary inertia has little influence on those wave modes which contain cut-off frequencies. For other wave modes, the rotary inertia results in a decrease in the wave speed in the high frequency region. This investigation may provide a useful guide in the applications of liposomes in ultrasound-based drug delivery and release.

Lamb Wave Propagation Study Using Frequency-Wavenumber Analysis

2012 ◽  
Author(s):  
Zhenhua Tian ◽  
Lingyu Yu
Keyword(s):  
Wave Propagation ◽  
Lamb Wave ◽  
Experimental Testing ◽  
Wave Spectrum ◽  
Laser Doppler Vibrometer ◽  
Wave Mode ◽  
Wavenumber Domain ◽  
Time Space ◽  
Lamb Wave Propagation ◽  
Wave Modes

Lamb waves are dispersive and multi-modal. Various wave modes make the interpretation of Lamb wave signal very difficult. It is desired that different modes can be separated for individual analysis. In the this paper, we present our studies on the multimodal Lamb wave propagation and wave mode extraction using frequency-wavenumber analysis. Wave spectrum in the frequency-wavenumber domain shows clear distinction among Lamb wave modes being present. This allows separating them or extracting a desired Lamb wave mode through a novel filtering strategy. Thus a single mode Lamb can be identified and extracted for certain types of damage detection in structural health monitoring (SHM). These concepts are illustrated through experimental testing. A scanning laser Doppler vibrometer is used to acquiring the time-space wavefield regarding the multimodal Lamb wave propagation. Then the recorded wavefield was analyzed in frequency-wavenumber domain and decomposed into different wave modes.

Wave propagation in a thin-walled liquid-filled initially stressed tube

1984 ◽  
Vol 141 ◽  
pp. 289-308 ◽  
Author(s):  
G. D. C. Kuiken
Keyword(s):  
Blood Pressure ◽  
Wave Propagation ◽  
Dispersion Equation ◽  
Newtonian Fluid ◽  
Initial Value Problem ◽  
Wave Mode ◽  
Initial Value ◽  
Thin Walled ◽  
Speed Of Propagation ◽  
Infinite Tube

Wave propagation through a thin-walled cylindrical orthotropic viscoelastic initially stressed tube filled with a Newtonian fluid is discussed. Special attention is drawn to the influence of the initial stretch on the wave propagation. It is shown that initial stretching of real arteries enhances the propagation of blood pressure pulses in mammalian arteries. The dispersion equation for the initial-value problem of a semi-infinite tube is also derived. It is shown that the speed of propagation and the attenuation vary with the distance from the support. The results obtained for the axial wave mode provide an explanation for the experimental observations, which is not possible with the results obtained for the infinite tube.

Evaluation of Adhesive Interface Properties in Honeycomb Sandwich Structure Using Guided Waves

2021 ◽  
Author(s):  
Parambeer Singh Negi ◽  
Dileep Koodalil ◽  
Krishnan Balasubramaniam
Keyword(s):  
Wave Propagation ◽  
Sandwich Structure ◽  
Guided Waves ◽  
Wave Mode ◽  
Guided Wave ◽  
Sh Wave ◽  
Bond Quality ◽  
Honeycomb Sandwich ◽  
Oriented Parallel ◽  
Honeycomb Sandwich Structure

Abstract A method is presented to evaluate the interfacial weakness of aluminium-based honeycomb sandwich structure (HSS) using Shear Horizontal (SH) guided wave. SH guided waves are sensitive to the interfacial properties since the wave particles vibration is oriented parallel to the adhesive-adherent joints. Periodic permanent magnet (PPM) electromagnetic acoustic transducers (EMATs) are used to excite and detect SH-guided waves. A semi-analytical finite element method is developed to simulate the SH wave propagation in HSS. The boundary stiffness approach is used to model the adhesive-adherent interface. The excitation parameters are chosen such that only SH0 mode is generated in the structure. The interaction of the fundamental SH0 wave mode with various defects and the different interface stiffness is analyzed. The frequency-wavenumber analysis is used to study the effect of interface stiffness on SH wave propagation. The analysis reveals that in a perfect bond, SH0 and S0 guided modes are present. The interaction of SH0 mode with the honeycomb core results in the genesis of S0 mode. Thus, the presence or absence of the S0 mode can be used as an indicator of bond quality. The findings from the FE simulation are validated against the experiment. The analysis shows a reliable non-destructive evaluation of the interface joint and classifying them as good or bad bonds.

Guided wave propagation in high-speed train axle and damage detection based on wave mode conversion

2015 ◽  
Vol 22 (9) ◽  
pp. 1133-1147 ◽  
Author(s):  
Fucai Li ◽  
Xuewei Sun ◽  
Jianxi Qiu ◽  
Limin Zhou ◽  
Hongguang Li ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Damage Detection ◽  
High Speed ◽  
Mode Conversion ◽  
Wave Mode ◽  
Guided Wave ◽  
High Speed Train ◽  
Guided Wave Propagation

scholarly journals Full wave simulations of fast wave mode conversion and lower hybrid wave propagation in tokamaks

2004 ◽  
Vol 11 (5) ◽  
pp. 2473-2479 ◽  
Author(s):  
J. C. Wright ◽  
P. T. Bonoli ◽  
M. Brambilla ◽  
F. Meo ◽  
E. D’Azevedo ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Mode Conversion ◽  
Wave Mode ◽  
Lower Hybrid ◽  
Fast Wave ◽  
Hybrid Wave ◽  
Lower Hybrid Wave ◽  
Full Wave

High Frequency Guided Wave Propagation and Scattering in Silicon Wafers

2021 ◽  
pp. 1-18
Author(s):  
Jean-Luc Robyr ◽  
Mathieu Simon ◽  
Bernard Masserey ◽  
Paul Fromme
Keyword(s):  
Wave Propagation ◽  
Wave Field ◽  
High Frequency ◽  
Surface Defects ◽  
Wave Mode ◽  
Guided Wave ◽  
Silicon Wafers ◽  
Monocrystalline Silicon ◽  
Custom Made

Abstract Thin monocrystalline silicon wafers are employed for the manufacture of solar cells with high conversion efficiency. Micro-cracks can be induced by the wafer cutting process, leading to breakage of the fragile wafers. High frequency guided waves allow for the monitoring of wafers and detection and characterization of surface defects. The material anisotropy of the monocrystalline silicon leads to variations of the guided wave characteristics, depending on the guided wave mode and propagation direction relative to the crystal orientation. Selective excitation of the first anti-symmetric A0 wave mode at 5 MHz center frequency was achieved experimentally using a custom-made wedge transducer. Strong wave pulses with limited beam skewing and widening were measured using non-contact laser interferometer measurements. This allowed the accurate characterization of the Lamb wave propagation and scattering at small artificial surface defects with a size of less than 100 µm. The surface extent of the defects of varying size was characterized using an optical microscope. The scattered guided wave field was evaluated, and characteristic parameters extracted and correlated to the defect size, allowing in principle detection of small defects. Further investigations are required to explain the systematic asymmetry of the guided wave field in the vicinity of the indents.

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