Forced wave propagation and energy distribution in anisotropic laminate composites

2011 ◽  
Vol 129 (5) ◽  
pp. 2923-2934 ◽  
Author(s):  
Evgeny Glushkov ◽  
Natalia Glushkova ◽  
Artem Eremin
Keyword(s):  
Wave Propagation ◽  
Energy Distribution ◽  
Laminate Composites ◽  
Forced Wave

Lamb Wave Propagation in Anisotropic Laminates

1990 ◽  
Vol 57 (4) ◽  
pp. 923-929 ◽  
Author(s):  
G. R. Liu ◽  
J. Tani ◽  
K. Watanabe ◽  
T. Ohyoshi
Keyword(s):  
Wave Propagation ◽  
Energy Distribution ◽  
Hybrid Composite ◽  
Lamb Wave ◽  
Composite Laminates ◽  
Strain Energy ◽  
Lamb Waves ◽  
Energy Distributions ◽  
Phase Velocities ◽  
Lamb Wave Propagation

The wave propagation in arbitrary anisotropic laminates is investigated on the basis of an exact theory. The dispersion relations of Lamb waves are determined for graphite/epoxy symmetric angle-ply laminates and hybrid composite ones which consist of carbon/epoxy and glass/epoxy layers. The dispersion and anisotropy of phase velocities for fundamental modes are discussed in detail. The energy distributions in the thickness direction of laminates are calculated for each kind of Lamb wave. A hybrid composite laminate is found to have better capability in absorbing impact energy by analyzing the strain energy distribution during the wave propagation. The results of the strain energy distribution are useful in determining the arrangement and the fiber orientation of the layers of hybrid composite laminates.

scholarly journals Free and forced wave propagation in beam lattice metamaterials with viscoelastic resonators

2021 ◽  
Vol 193 ◽  
pp. 106129 ◽  
Author(s):  
Francesca Vadalá ◽  
Andrea Bacigalupo ◽  
Marco Lepidi ◽  
Luigi Gambarotta
Keyword(s):  
Wave Propagation ◽  
Forced Wave ◽  
Beam Lattice

Displacement and Strain-Energy Distribution in a Longitudinally Vibrating Cylindrical Rod With a Viscoelastic Coating

1962 ◽  
Vol 29 (1) ◽  
pp. 47-52 ◽  
Author(s):  
P. Hertelendy
Keyword(s):  
Wave Propagation ◽  
Energy Distribution ◽  
Cross Section ◽  
Lower Bounds ◽  
Loss Factor ◽  
Strain Energy ◽  
Frequency Equation ◽  
Upper And Lower Bounds ◽  
Viscoelastic Parameters ◽  
Longitudinal Wave Propagation

A numerical solution by R. M. Davies of the Pochhammer frequency equation is used to determine the displacement and strain-energy distribution across the cross section of an infinite elastic circular cylindrical rod for a number of wave lengths of the first, second, and third modes of symmetrical longitudinal wave propagation. With these results the effect of a thin uniform layer of viscoelastic material is investigated. The four viscoelastic parameters of the coating are reduced to one in the definition and computation of upper and lower bounds of the loss factor, and the application of results to experimental work is discussed.

The Study of Insulator Influence to the Electromagnetic Wave Propagation in GIS

2013 ◽  
Vol 860-863 ◽  
pp. 2145-2148
Author(s):  
Guo Qing Jiang ◽  
Dong Sheng Xu ◽  
Zhao Li ◽  
Lu Li ◽  
Yi Wang ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Wave ◽  
Energy Distribution ◽  
Simulation Model ◽  
Electromagnetic Wave Propagation ◽  
Partial Discharge ◽  
Great Influence ◽  
Fdtd Simulation ◽  
Gis Model ◽  
Insulation Breakdown

GIS is the key equipment in power grid and partial discharge is the main cause leading to insulation breakdown. UHF detection is an effective method for PD detection in GIS. The insulator has great influence to the electromagnetic wave propagation in GIS. The FDTD simulation model of GIS is setup to study the influence of insulator to electromagnetic wave propagation. The amplitude and energy distribution at GIS model with and without insulator are study in this paper.

scholarly journals Free and Forced Wave Motion in a Two-Dimensional Plate with Radial Periodicity

2021 ◽  
Vol 11 (22) ◽  
pp. 10948
Author(s):  
Elisabetta Manconi ◽  
Sergey V. Sorokin ◽  
Garziera Rinaldo ◽  
Matheus Mikael Quartaroli
Keyword(s):  
Wave Propagation ◽  
Forced Response ◽  
Polar Coordinates ◽  
Element Analysis ◽  
Forced Wave ◽  
Practical Engineering ◽  
Approaches To Study ◽  
Flow Through ◽  
Waves Propagation ◽  
Numerical Approaches

In many practical engineering situations, a source of vibrations may excite a large and flexible structure such as a ship’s deck, an aeroplane fuselage, a satellite antenna, a wall panel. To avoid transmission of the vibration and structure-borne sound, radial or polar periodicity may be used. In these cases, numerical approaches to study free and forced wave propagation close to the excitation source in polar coordinates are desirable. This is the paper’s aim, where a numerical method based on Floquet-theory and the FE discretision of a finite slice of the radial periodic structure is presented and verified. Only a small slice of the structure is analysed, which is approximated using piecewise Cartesian segments. Wave characteristics in each segment are obtained by the theory of wave propagation in periodic Cartesian structures and Finite Element analysis, while wave amplitude change due to the changes in the geometry of the slice is accommodated in the model assuming that the energy flow through the segments is the same. Forced response of the structure is then evaluated in the wave domain. Results are verified for an infinite isotropic thin plate excited by a point harmonic force. A plate with a periodic radial change of thickness is then studied. Free waves propagation are shown, and the forced response in the nearfield is evaluated, showing the validity of the method and the computational advantage compared to FE harmonic analysis for infinite structures.

Electron Microscopy of Shock Loaded Polycrystalline Beryllium

1974 ◽  
Vol 32 ◽  
pp. 506-507 ◽  
Author(s):  
J. M. Galbraith ◽  
L. E. Murr ◽  
A. L. Stevens
Keyword(s):  
Electron Microscopy ◽  
Wave Propagation ◽  
Structural Change ◽  
Single Crystal ◽  
Diffraction Pattern ◽  
Shock Loading ◽  
Slip Systems ◽  
Compression Tests ◽  
X Ray Diffraction ◽  
X Ray

Uniaxial compression tests and hydrostatic tests at pressures up to 27 kbars have been performed to determine operating slip systems in single crystal and polycrystal1ine beryllium. A recent study has been made of wave propagation in single crystal beryllium by shock loading to selectively activate various slip systems, and this has been followed by a study of wave propagation and spallation in textured, polycrystal1ine beryllium. An alteration in the X-ray diffraction pattern has been noted after shock loading, but this alteration has not yet been correlated with any structural change occurring during shock loading of polycrystal1ine beryllium.This study is being conducted in an effort to characterize the effects of shock loading on textured, polycrystal1ine beryllium. Samples were fabricated from a billet of Kawecki-Berylco hot pressed HP-10 beryllium.

Energy Distribution in Electron Beams

1972 ◽  
Vol 30 ◽  
pp. 568-569
Author(s):  
Tamotsu Ohno
Keyword(s):  
Electron Beam ◽  
Energy Distribution ◽  
Cross Section ◽  
Integral Curve ◽  
Electron Beams ◽  
Electron Gun ◽  
Angular Divergence ◽  
Apparent Increase ◽  
Integral Width ◽  
The Cross

The energy distribution in an electron; beam from an electron gun provided with a biased Wehnelt cylinder was measured by a retarding potential analyser. All the measurements were carried out with a beam of small angular divergence (<3xl0-4 rad) to eliminate the apparent increase of energy width as pointed out by Ichinokawa.The cross section of the beam from a gun with a tungsten hairpin cathode varies as shown in Fig.1a with the bias voltage Vg. The central part of the beam was analysed. An example of the integral curve as well as the energy spectrum is shown in Fig.2. The integral width of the spectrum ΔEi varies with Vg as shown in Fig.1b The width ΔEi is smaller than the Maxwellian width near the cut-off. As |Vg| is decreased, ΔEi increases beyond the Maxwellian width, reaches a maximum and then decreases. Note that the cross section of the beam enlarges with decreasing |Vg|.

Effects of high pressure on the crystallization of carbon fiber reinforced polyetheretherketone (CF/PEEK) laminate composites

1990 ◽  
Vol 48 (4) ◽  
pp. 876-877
Author(s):  
Hong-Ming Lin ◽  
C. H. Liu ◽  
R. F. Lee
Keyword(s):  
High Pressure ◽  
Carbon Fiber ◽  
Sample Surface ◽  
High Yield ◽  
Fiber Reinforced ◽  
Laminate Composites ◽  
Peek Composite ◽  
Continuous Carbon Fiber ◽  
Carbon Fiber Reinforced

Polyetheretherketone (PEEK) is a crystallizable thermoplastic used as composite matrix materials in application which requires high yield stress, high toughness, long term high temperature service, and resistance to solvent and radiation. There have been several reports on the crystallization behavior of neat PEEK and of CF/PEEK composite. Other reports discussed the effects of crystallization on the mechanical properties of PEEK and CF/PEEK composites. However, these reports were all concerned with the crystallization or melting processes at or close to atmospheric pressure. Thus, the effects of high pressure on the crystallization of CF/PEEK will be examined in this study.The continuous carbon fiber reinforced PEEK (CF/PEEK) laminate composite with 68 wt.% of fibers was obtained from Imperial Chemical Industry (ICI). For the high pressure experiments, HIP was used to keep these samples under 1000, 1500 or 2000 atm. Then the samples were slowly cooled from 420 °C to 60 °C in the cooling rate about 1 - 2 degree per minute to induce high pressure crystallization. After the high pressure treatment, the samples were scanned in regular DSC to study the crystallinity and the melting temperature. Following the regular polishing, etching, and gold coating of the sample surface, the scanning electron microscope (SEM) was used to image the microstructure of the crystals. Also the samples about 25mmx5mmx3mm were prepared for the 3-point bending tests.

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