WAVE PROPAGATION CHARACTERISTICS OF THIN SHELLS OF REVOLUTION BY FREQUENCY–WAVE NUMBER SPECTRUM METHOD

2002 ◽  
Vol 251 (2) ◽  
pp. 367-372 ◽  
Author(s):  
J. ZHANG ◽  
L. JIA ◽  
Y. SHU
Keyword(s):  
Wave Propagation ◽  
Wave Number ◽  
Thin Shells ◽  
Propagation Characteristics ◽  
Shells Of Revolution ◽  
Frequency Wave ◽  
Spectrum Method

A Spectral Finite Element Model for Wave Propagation Analysis in Laminated Composite Plate

2006 ◽  
Vol 128 (4) ◽  
pp. 477-488 ◽  
Author(s):  
A. Chakraborty ◽  
S. Gopalakrishnan
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
Shear Deformation ◽  
Mechanical Response ◽  
Laminated Composite ◽  
Wave Number ◽  
Single Element ◽  
Element Formulation ◽  
Frequency Wave ◽  
Spectral Finite Element

A new spectral plate element (SPE) is developed to analyze wave propagation in anisotropic laminated composite media. The element is based on the first-order laminated plate theory, which takes shear deformation into consideration. The element is formulated using the recently developed methodology of spectral finite element formulation based on the solution of a polynomial eigenvalue problem. By virtue of its frequency-wave number domain formulation, single element is sufficient to model large structures, where conventional finite element method will incur heavy cost of computation. The variation of the wave numbers with frequency is shown, which illustrates the inhomogeneous nature of the wave. The element is used to demonstrate the nature of the wave propagating in laminated composite due to mechanical impact and the effect of shear deformation on the mechanical response is demonstrated. The element is also upgraded to an active spectral plate clement for modeling open and closed loop vibration control of plate structures. Further, delamination is introduced in the SPE and scattered wave is captured for both broadband and modulated pulse loading.

Harmonic Wave Propagation in a Periodically Layered, Infinite Elastic Body: Plane Strain, Analytical Results

1979 ◽  
Vol 46 (1) ◽  
pp. 113-119 ◽  
Author(s):  
T. J. Delph ◽  
G. Herrmann ◽  
R. K. Kaul
Keyword(s):  
Wave Propagation ◽  
Asymptotic Behavior ◽  
Plane Strain ◽  
Elastic Body ◽  
Harmonic Wave ◽  
Wave Number ◽  
Periodic Medium ◽  
Frequency Wave ◽  
Wave Numbers ◽  
Band Characteristic

The problem of harmonic wave propagation in an unbounded, periodically layered elastic body in a state of plane strain is examined. The dispersion spectrum is shown to be governed by the roots of an 8 × 8 determinant, and represents a surface in frequency-wave number space. The spectrum exhibits the typical stopping band characteristic of wave propagation in a periodic medium. The dispersion equation is shown to uncouple along the ends of the Brillouin zones, and also in the case of wave propagation normal to the layering. The significance of this uncoupling is examined. Also, the asymptotic behavior of the spectrum for large values of the wave numbers is investigated.

COHERENCE AND STRUCTURE

Geophysics ◽  
1974 ◽  
Vol 39 (1) ◽  
pp. 81-84 ◽  
Author(s):  
H. Mack
Keyword(s):  
Spatial Coherence ◽  
Seismic Source ◽  
Wave Number ◽  
Underlying Structure ◽  
Propagation Characteristics ◽  
Frequency Wave ◽  
The Earth

The wavefield generated at the surface of the earth from a surface seismic source can be represented as a function F(f, k) in the frequency wave‐number domain. This function depends upon the source and the propagation characteristics of the underlying structure. For any particular frequency the spatial coherence as observed at two points [Formula: see text] and [Formula: see text] on the surface is defined as: [Formula: see text]

Harmonic Wave Propagation in a Periodically Layered, Infinite Elastic Body: Antiplane Strain

1978 ◽  
Vol 45 (2) ◽  
pp. 343-349 ◽  
Author(s):  
T. J. Delph ◽  
G. Herrmann ◽  
R. K. Kaul
Keyword(s):  
Wave Propagation ◽  
Elastic Medium ◽  
Elastic Body ◽  
Dispersion Equation ◽  
Harmonic Wave ◽  
Wave Number ◽  
Harmonic Waves ◽  
Antiplane Strain ◽  
Frequency Wave ◽  
Asymptotic Values

The propagation of horizontally polarized shear waves through a periodically layered elastic medium is analyzed. The dispersion equation is obtained by using Floquet’s theory and is shown to define a surface in frequency-wave number space. The important features of the surface are the passing and stopping bands, where harmonic waves are propagated or attenuated, respectively. Other features of the spectrum, such as uncoupling at the ends of the Brillouin zones, conical points, and asymptotic values at short wavelengths, are also examined.

Wave Propagation Analysis in Anisotropic Plate Using Wavelet Spectral Element Approach

2008 ◽  
Vol 75 (1) ◽  
Author(s):  
Mira Mitra ◽  
S. Gopalakrishnan
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
Differential Equations ◽  
Laminated Composite ◽  
Composite Plates ◽  
Spectral Element ◽  
Wave Number ◽  
Frequency Wave ◽  
Propagation Analysis ◽  
Spectral Finite Element

In this paper, a 2D wavelet-based spectral finite element (WSFE) is developed for a anisotropic laminated composite plate to study wave propagation. Spectral element model captures the exact inertial distribution as the governing partial differential equations (PDEs) are solved exactly in the transformed frequency-wave-number domain. Thus, the method results in large computational savings compared to conventional finite element (FE) modeling, particularly for wave propagation analysis. In this approach, first, Daubechies scaling function approximation is used in both time and one spatial dimensions to reduce the coupled PDEs to a set of ordinary differential equations (ODEs). Similar to the conventional fast Fourier transform (FFT) based spectral finite element (FSFE), the frequency-dependent wave characteristics can also be extracted directly from the present formulation. However, most importantly, the use of localized basis functions in the present 2D WSFE method circumvents several limitations of the corresponding 2D FSFE technique. Here, the formulated element is used to study wave propagation in laminated composite plates with different ply orientations, both in time and frequency domains.

In-plane elastic wave propagation in aluminum honeycomb cores fabricated by bonding corrugated sheets

2017 ◽  
Vol 21 (8) ◽  
pp. 2949-2974 ◽  
Author(s):  
Ammar Ahmed ◽  
Maen Alkhader ◽  
Bassam Abu-Nabah
Keyword(s):  
Wave Propagation ◽  
Sandwich Structure ◽  
Propagation Characteristics ◽  
Promising Alternative ◽  
Frequency Wave ◽  
Limited Effectiveness ◽  
Aluminum Honeycomb ◽  
Corrugated Sheets ◽  
Honeycomb Cores ◽  
Ultrasound Inspection

Aluminum honeycomb cores are widely used in sandwich structures due to their high stiffness-to-weight ratios and very low densities. However, owing to their porous architecture, honeycomb cores are inherently week and are susceptible to damage due to inadvertent or improper loadings on their encompassing sandwich structure. This damage can potentially lead to the failure of the sandwich structure, and therefore it should be detected and evaluated, preferably using nondestructive methods. Common nondestructive techniques have limited effectiveness in inspecting aluminum honeycombs due to their porous structure and dispersive properties. Since honeycombs are less dispersive at sub-ultrasound frequencies, inspecting them using low and sub-ultrasound frequencies has been introduced lately as a promising alternative to ultrasound inspection. However, this approach requires a priori knowledge of the wave propagation characteristics in the inspected material, which is not readily available for most commercially available aluminum honeycombs, especially the ones manufactured by joining thin corrugated sheets. Thus, this work utilizes finite element computations to assess the low frequency wave propagation characteristics (i.e. phase velocity and dispersive properties) in commercially available aluminum honeycombs made by bonding thin corrugated sheets. Results illustrate that the dispersive behavior and acoustic anisotropy of the studied honeycombs are more significant at higher porosities and high frequencies as well as identify the frequencies below which honeycombs exhibit their least dispersive acoustic behavior.

MODELLING OF ACOUSTIC EMISSION SOURCE AND WAVE RESPONSE IN LAYERED MATERIALS

2014 ◽  
Vol 44 (1) ◽  
pp. 21-44 ◽  
Author(s):  
A. Alamin ◽  
R. Zhang
Keyword(s):  
Acoustic Emission ◽  
Wave Propagation ◽  
Integral Transformation ◽  
Layered Media ◽  
Transformation Method ◽  
Wave Number ◽  
Dislocation Source ◽  
Frequency Wave ◽  
Wave Response ◽  
Time Space

Abstract This study proposes a model of wave propagation in layered media for the use in acoustic emission (AE) studies. This model aims to find an AE response at a free surface to the propagating waves originating at a dislocation source either in one layer medium or a layer-to-layer interface. Each of the layered media is assumed to be homogenous, linear elastic and isotropic. An integral transformation method has been applied to determine the wave response in frequency-wave number domain, which is then converted to time-space domain. In the numerical examples, we first select truncated values with the finite integral transformation, so that no wave interference happens in the responses from wave reflection at truncated boundaries. Next, we simulate wave propagation in an elastic half space, and compare results obtained with that from other kind bottom boundary. Next, we introduce a dis- location source in interface and compare a simulated AE wave response obtained with that computed in the layered medium to demonstrate the performance of the model. In each simulation, the results show good agreement with the reference solutions.

Wave Propagation Characteristics on a Pipe-Type Cable in Particular Reference to the Proximity Effect

2013 ◽  
Vol 133 (12) ◽  
pp. 954-960 ◽  
Author(s):  
Akihiro Ametani ◽  
Kazuki Kawamura ◽  
Asha Shendge ◽  
Naoto Nagaoka ◽  
Yoshihiro Baba
Keyword(s):  
Wave Propagation ◽  
Proximity Effect ◽  
Propagation Characteristics

Maysel's formula generalized for piezoelectric vibrations - Application to thin shells of revolution

1996 ◽  
Author(s):  
Hans Irschik ◽  
Franz Ziegler ◽  
Hans Irschik ◽  
Franz Ziegler
Keyword(s):  
Thin Shells ◽  
Shells Of Revolution
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