Detection of delamination in composites by using electromagnetic penetrating radar

2014 ◽  
Vol 5 (2) ◽  
pp. 151-156
Author(s):  
Z. Mechbal ◽  
A. Khamlichi
Keyword(s):  
Electromagnetic Wave ◽  
Electromagnetic Waves ◽  
Electromagnetic Wave Propagation ◽  
Wave Reflection ◽  
Image Features ◽  
Partial Reflection ◽  
Straight Path ◽  
Reflected Signal ◽  
Short Time ◽  
Intervening Factors

Composites made from E-glass/epoxy or aramid/epoxy are frequently used in aircraft and aerospace industries. These materials are prone to suffer from the presence of delamination, which can reduce severely the performance of aircrafts and even threaten their safety. Since electric conductivity of these composites is rather small, they can propagate electromagnetic waves. Detection of delamination damage can then be monitored by using an electromagnetic penetrating radar scanner, which consists of emitting waves having the form of short time pulses that are centered on a given work frequency. While propagating, these waves undergo partial reflection when running into an obstacle or a material discontinuity. Habitually, the radar is moved at constant speed along a straight path and the reflected signal is processed as a radargram that gives the reflected energy as function of the two-way time and the antenna position.In this work, modeling of electromagnetic wave propagation in composites made from E-glass/epoxy was performed analytically. The electromagnetic wave reflection from a delamination defect was analyzed as function of key intervening factors which include the defect extent and depth, as well as the work frequency. Various simulations were performed and the obtained results have enabled to correlate the reflection pattern image features to the actual delamination defect characteristics which can provide quantification of delamination.

Electromagnetic wave propagation in a chiroplasma-filled waveguide

1999 ◽  
Vol 62 (1) ◽  
pp. 87-94 ◽  
Author(s):  
J. GONG
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Wave ◽  
Cross Section ◽  
Electromagnetic Waves ◽  
Electromagnetic Wave Propagation ◽  
Propagation Constant ◽  
Circular Cross Section ◽  
Propagation Characteristics ◽  
Waveguide Modes ◽  
The Family

A dispersion equation is derived for a cylindrical waveguide of circular cross-section partially filled with chiroplasma. The propagation characteristics of electromagnetic waves in the family of waveguide modes are studied. The dispersion curves are given. It is found that the propagation constant changes almost linearly with the chirality admittance for the parameters that we choose, and increases with increasing filled area.

Rayleigh surface waves along the boundary between a plasma and a metallic screen

1993 ◽  
Vol 49 (2) ◽  
pp. 227-235 ◽  
Author(s):  
S. T. Ivanov ◽  
K. M. Ivanova ◽  
E. G. Alexov
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Wave ◽  
Surface Waves ◽  
Electromagnetic Waves ◽  
Electromagnetic Wave Propagation ◽  
Cyclotron Frequency ◽  
Plasma Frequency ◽  
Magnetoactive Plasma ◽  
Rayleigh Surface Waves ◽  
The Waves

Electromagnetic wave propagation along the interface between a magnetoactive plasma and a metallic screen is investigated analytically and numerically. It is shown that the waves have a Rayleigh character: they are superpositions of two partial waves. It is concluded that electromagnetic waves propagate only at frequencies lower than min (ωp, ωc), where ωpis the plasma frequency and ωcis the cyclotron frequency. The field topology is found, and the physical character of the waves is discussed.

Effect of Anisotropic Characteristics of Composite Skins on the Electromagnetic Wave Propagation in the Foam Core Sandwich Structures

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1782-1787 ◽  
Author(s):  
Heoung Jae Chun ◽  
Hyun Su Shin
Keyword(s):  
Electromagnetic Wave ◽  
Fiber Orientation ◽  
Electromagnetic Waves ◽  
Composite Laminate ◽  
Electromagnetic Wave Propagation ◽  
Sandwich Structures ◽  
Incident Angle ◽  
Foam Core ◽  
Linearly Polarized ◽  
Composite Skins

The propagation of electromagnetic waves in the foam core sandwich structures is highly affected by anisotropic permittivity and loss tangent of composite skins. Even though many investigations were focused on the propagation of electromagnetic waves in the composite materials in last several decades, little investigations were carried out to understand adequately the propagation of the electromagnetic waves in the foam core sandwich structures. In this study, the transmittance of the arbitrary linearly polarized incident TEM waves through the solid composite laminate with various stacking sequences and foam core sandwich structures with composite skins was calculated as functions of fiber orientation of composites and incident angle of the wave by the analytical model.

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.

scholarly journals NUMERICAL METHOD FOR ELECTROMAGNETIC WAVE PROPAGATION PROBLEM IN A CYLINDRICAL INHOMOGENEOUS METAL DIELECTRIC WAVEGUIDING STRUCTURES

2017 ◽  
Vol 22 (3) ◽  
pp. 271-282 ◽  
Author(s):  
Eugene Smolkin
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Wave ◽  
Electromagnetic Waves ◽  
Electromagnetic Wave Propagation ◽  
Physical Problem ◽  
Dielectric Waveguides ◽  
Spectral Parameters ◽  
Transmission Eigenvalue ◽  
Wave Propagation Problem ◽  
Transmission Eigenvalue Problem

The propagation of monochromatic electromagnetic waves in metal circular cylindrical dielectric waveguides filled with inhomogeneous medium is considered. The physical problem is reduced to solving a transmission eigenvalue problem for a system of ordinary differential equations. Spectral parameters of the problem are propagation constants of the waveguide. Numerical results are found with a projection method. The comparison with known exact solutions (for particular values of parameters) is made.

Propagation of electromagnetic waves in a density-modulated plasma

1991 ◽  
Vol 45 (2) ◽  
pp. 173-190 ◽  
Author(s):  
Maurizio Lontano ◽  
Nicolai Lunin
Keyword(s):  
Electromagnetic Wave ◽  
Transmission Coefficient ◽  
Electromagnetic Waves ◽  
Electromagnetic Wave Propagation ◽  
Plasma Layer ◽  
Single Layer ◽  
Resonant Interaction ◽  
Explicit Computation ◽  
Single Plasma

The properties of electromagnetic wave propagation in a uniformly densitymodulated plasma are studied, starting from a unidimensional scalar wave (Hill) equation for the wave electric field. Introduction of the formalism of the spatial propagator Q(z2, z1), from the point z1 to the point z2 allows reduction of the problem to determination of the propagator relevant to a single plasma layer that constitutes the entire periodic structure. The transmission coefficient of a single layer can be computed for any kind of density profile by means of the Magnus approximation, satisfying energy flux conservation at each order in the relevant expansion. The appearance of ‘forbidden zones’ in parameter space leads to the possibility that the incident electromagnetic wave can be partially or completely reflected if a sufficient number of periods are present. The explicit computation of the transmission coefficient for a series of n successive layers confirms this effect as the result of a ‘resonant’ interaction of the incident wave and the ‘periodicity’ of the medium.

Electromagnetic wave propagation in an inhomogeneous gyrational medium

1971 ◽  
Vol 69 (3) ◽  
pp. 457-463 ◽  
Author(s):  
B. S. Westcott
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Wave ◽  
Electromagnetic Waves ◽  
Electromagnetic Wave Propagation ◽  
Transmission Coefficients ◽  
Resonance Properties

AbstractThe investigation of a recently devised model in which the permittivity profile takes the form of an asymmetrical Epstein layer is adapted for use in a gyrational medium. Reflexion and transmission coefficients for normally incident electromagnetic waves are obtained and resonance properties are discussed.

scholarly journals The Speed Electromagnetic Wave Propagation in the Snow-Ice Underlying Surface

2021 ◽  
pp. 332-346
Author(s):  
Vladimir A. Malyshev ◽  
Viktor G. Mashkov
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Wave ◽  
Water Content ◽  
Liquid Water ◽  
Electromagnetic Waves ◽  
Electromagnetic Wave Propagation ◽  
Liquid Water Content ◽  
Ice Cover ◽  
Underlying Surface ◽  
Speed Propagation

The results calculations the electromagnetic wave propagation velocity in the snow-ice cover depending on the density, the proportion liquid water content, and the propagation speeds the electromagnetic wave in dry snow, dry firn, and dry ice vary very markedly depending on the proportion liquid water content, the preferred orientation, and the shape ice and air structure are presented. The inclusions in the snow. The performed estimates the complex relative permittivity the medium that determines the speed propagation electromagnetic waves show a noticeable influence the density, the proportion liquid water content and the structure the underlying surface (snow, firn, ice), which allows identifying the layers the underlying surface in order to remotely determine the possibility landing a helicopter-type aircraft on an unprepared site with snow-ice cover. Shown, when the portion the water content in the medium is equal to zero, which is typical for negative temperatures, the speed propagation electromagnetic waves in the medium will depend on the density the medium and structure the dry ice in a small range of 1 m/μs temperature. In dry snow, vertically and horizontally elongated or spherical inclusions make a significant contribution to the change in the speed propagation the electromagnetic wave. At zero temperature, in the frequency range of 2 ... 8 GHz, the share water content in the medium, the density and structure the medium will play a determining role in the speed propagation an electromagnetic wave in the medium. The purpose this article is to determine the change ranges speed propagation electromagnetic waves in snow-ice the underlying surface depending on the density, structure, water content to restore the structure the snow and ice according to radar sensing, a more accurate determination the depth snow and thickness ice cover used in the assessment the possibility the safe landing an aircraft the helicopter type on an unprepared ground with snow-ice cover

scholarly journals Cross-polarization of electromagnetic waves reflected by anisotropic gradient planar structures

2019 ◽  
Vol 30 ◽  
pp. 12017
Author(s):  
Natalja Moiseeva
Keyword(s):  
Electromagnetic Wave ◽  
Electromagnetic Waves ◽  
Wave Reflection ◽  
Optical Axis ◽  
Wkb Method ◽  
Cross Polarization ◽  
Planar Structures ◽  
Reflection Matrix ◽  
The Matrix ◽  
The Waves

The results of calculating the moduli of the coefficients of the electromagnetic wave reflection matrix (EMW) at the boundary of an inhomogeneous anisotropic medium with torsion using the matrix form of the Wentzel-Kramers-Brillouin (WKB) method are presented. The effect of the orientation of the optical axis and the torsion angle on the polarization of the waves propagating in the medium and on the off-diagonal coefficients of the reflection matrix is shown.

scholarly journals Investigation of the channel for information transfer by electric, electromagnetic and acoustic waves in layered environment with ice cover

2020 ◽  
Vol 196 ◽  
pp. 02014
Author(s):  
Vladimir Korochentsev ◽  
Vey Syue ◽  
Viktor Petrosyants ◽  
Artem Em ◽  
Ivan Garasev ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Wave ◽  
Acoustic Waves ◽  
Electromagnetic Waves ◽  
Information Transfer ◽  
Electromagnetic Wave Propagation ◽  
Low Frequency ◽  
Acoustic Signals ◽  
Half Wave ◽  
To Receive

A theoretical model of electromagnetic wave propagation in an ice layer was developed. A half-wave vibrator frozen in an ice layer is used as a receiving-radiating system of electromagnetic waves. Schemes of developed acoustic low-frequency radiators based on electric sparks are described. The possibility of application of the developed systems to receive acoustic signals from earthquake ice source is under discussion.

Sign in / Sign up

Export Citation Format

Share Document