scholarly journals Wave Dispersion in Multilayered Reinforced Nonlocal Plates under Nonlinearly Varying Initial Stress

Eng ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 31-47
Author(s):  
Mohammad Reza Farajpour ◽  
Ali Reza Shahidi ◽  
Ali Farajpour
Keyword(s):  
Wave Propagation ◽  
Initial Stress ◽  
Volume Fraction ◽  
Wave Dispersion ◽  
Initial Stresses ◽  
Small Scale ◽  
Dependent Model ◽  
Phase And Group Velocities ◽  
The One ◽  
Group Velocities

This paper deals with the effects of initial stress on wave propagations in small-scale plates with shape memory alloy (SMA) nanoscale wires. The initial stress is exerted on the small-scale plate along both in-plane directions. A scale-dependent model of plates is developed for taking into consideration size influences on the wave propagation. In addition, in order to take into account the effects of SMA nanoscale wires, the one-dimensional Brinson’s model is applied. A set of coupled differential equations is obtained for the non-uniformly prestressed small-scale plate with SMA nanoscale wires. An exact solution is obtained for the phase and group velocities of the prestressed small-scale system. The influences of non-uniformly distributed initial stresses as well as scale and SMA effects on the phase and group velocities are explored and discussed. It is found that initial stresses as well as the orientation and volume fraction of SMA nanoscale wires can be used as a controlling factor for the wave propagation characteristics of small-scale plates.

scholarly journals The Effect of Viscosity and Heterogeneity on Propagation of G–Type Waves

2017 ◽  
Vol 27 (2) ◽  
pp. 253-260
Author(s):  
Shishir Gupta ◽  
Keyword(s):  
Wave Propagation ◽  
Closed Form ◽  
Dispersion Equation ◽  
Initial Stress ◽  
Half Space ◽  
Plane Surface ◽  
Lower Half Space ◽  
Type Wave ◽  
Phase And Group Velocities ◽  
Group Velocities

AbstractEarthquakes yield motions of massive rock layers accompanied by vibrations which travel in waves. This paper analyses the possibility of G-type wave propagation along the plane surface at the interface of two different media which is assumed to be heterogeneous and viscoelastic. The upper layer is considered to be viscoelastic and the lower half space is considered to be an initially stressed heterogeneous half space. The dispersion equation, as well as the phase and group velocities, is obtained in closed form. The dispersion equation agrees with the classical Love type wave. The effects of the nonhomogeneity of the parameters and the initial stress on the phase and group velocities are expressed by means of a graph.

scholarly journals Rayleigh Wave Dispersion for a Single Layer on an Elastic Half Space

1960 ◽  
Vol 13 (3) ◽  
pp. 498 ◽  
Author(s):  
BA Bolt ◽  
JC Butcher
Keyword(s):  
Numerical Solutions ◽  
Single Layer ◽  
Wave Dispersion ◽  
Elastic Half Space ◽  
Seismic Parameters ◽  
Period Equation ◽  
Phase And Group Velocities ◽  
The University ◽  
Rayleigh Wave Dispersion ◽  
Group Velocities

Numerical solutions of the period equation for Rayleigh waves in a single surface layer were calculated using the SILLIAC computer at the University of Sydney. Values of the phase and group velocities for both the fundamental and first higher mode are tabulated against period for eleven models. These related models allow a sensitivity analysis of the effect of variation in the seismic parameters.

WAVE PROPAGATION IN RECTANGULAR NANOPLATES BASED ON STRAIN GRADIENT THEORY WITH ONE GRADIENT PARAMETER WITH CONSIDERING INITIAL STRESS

2014 ◽  
Vol 28 (03) ◽  
pp. 1450021 ◽  
Author(s):  
MOHAMMAD RAHIM NAMI ◽  
MAZIAR JANGHORBAN
Keyword(s):  
Wave Propagation ◽  
Initial Stress ◽  
Governing Equation ◽  
Gradient Elasticity ◽  
Initial Stresses ◽  
Strain Gradient Theory ◽  
Gradient Theory ◽  
Gradient Parameter ◽  
Gradient Elasticity Theory ◽  
Parameter Wave

In this paper, on the basis of gradient elasticity theory with one gradient parameter, wave propagation in rectangular nanoplates is studied. In the governing equation, the influences of initial stresses and elastic foundation are also considered. An analytical approach is used to solve the governing equation. The effects of different parameters such as gradient parameter on the circular and cut-off frequencies are presented. One can see that the initial stress and gradient parameter play an important role in investigating the wave propagation in nanoplates.

scholarly journals Small-Scale Effect on Longitudinal Wave Propagation in Laser-Excited Plates

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
F. Kh. Mirzade
Keyword(s):  
Wave Propagation ◽  
Longitudinal Wave ◽  
Wave Dispersion ◽  
Defect Concentration ◽  
Elastic Displacement ◽  
Small Scale ◽  
Elastic Diffusion ◽  
Diffusion Instability ◽  
Solid Plate ◽  
Longitudinal Wave Propagation

Longitudinal wave propagation in an elastic isotopic laser-excited solid plate with atomic defect (vacancies, interstitials) generation is studied by the nonlocal continuum model. The nonlocal differential constitutive equations of Eringen are used in the formulations. The coupled governing equations for the dynamic of elastic displacement and atomic defect concentration fields are obtained. The frequency equations for the symmetrical and antisymmetrical motions of the plate are found and discussed. Explicit expressions for different characteristics of waves like phase velocity and attenuation (amplification) coefficients are derived. It is shown that coupling between the displacement and defect concentration fields affects the wave dispersion characteristics in the nonlocal elasticity. The dispersion curves of the elastic-diffusion instability are investigated for different pump parameters and larger wave numbers.

scholarly journals A Numerical Simulation of Blasting Stress Wave Propagation in a Jointed Rock Mass under Initial Stresses

2021 ◽  
Vol 11 (17) ◽  
pp. 7873
Author(s):  
Qian Dong ◽  
Xinping Li ◽  
Yongsheng Jia ◽  
Jinshan Sun
Keyword(s):  
Wave Propagation ◽  
Rock Mass ◽  
Initial Stress ◽  
Stress Wave ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Stress Waves ◽  
Initial Stresses ◽  
Stress Wave Propagation ◽  
Rock Masses

The initial stresses have a strong effect on the mechanical behavior of underground rock masses, and the initial stressed rock masses are usually under strong dynamic disturbances such as blasting and earthquakes. The influence mechanism of a blasting excavation on underground rock masses can be revealed by studying the propagation of stress waves in them. In this paper, the improved Mohr-Coulomb elasto-plastic constitutive model of the intact rock considering the initial damage was first established and numerically implemented in Universal Distinct Element Code (UDEC) based on the variation of the experimental stress wave velocity in the initial stressed intact rock, and the feasibility of combining the established rock constitutive model and the BB (Bandis-Barton) model which characterizes the nonlinear deformation of the joints to simulate stress waves across jointed rock masses under initial stress was validated by comparing the numerical and model test results subsequently. Finally, further parameter studies were carried out through the UDEC to investigate the effect of the initial stress, angle, and number of joints on the transmission of the blasting stress wave in the jointed rock mass. The results showed that the initial stress significantly changed the propagation of the stress waves in the jointed rock mass. When the initial stress was small, the transmission coefficients of the stress waves in the jointed rock were vulnerable to be influenced by the variation of the angle and the number of joints, while the effect of the angle and the number of joints on the stress wave propagation gradually weakened as the initial stress increased.

A Dispersive Nonlocal Model for In-Plane Wave Propagation in Laminated Composites With Periodic Structures

2015 ◽  
Vol 82 (3) ◽  
Author(s):  
H. Brito-Santana ◽  
Yue-Sheng Wang ◽  
R. Rodríguez-Ramos ◽  
J. Bravo-Castillero ◽  
R. Guinovart-Díaz ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Plane Wave ◽  
Phase Velocity ◽  
Incident Angle ◽  
Unit Cell ◽  
Wave Number ◽  
Periodic Distribution ◽  
Phase And Group Velocities ◽  
Group Velocities ◽  
Plane Wave Propagation

In this paper, the problem of in-plane wave propagation with oblique incidence of the wave in an isotropic bilaminated composite under perfect contact between the layers and periodic distribution between them is studied. Based on an asymptotic dispersive method for the description of the dynamic processes, the dispersion equations were derived analytically from the average model. Numerical examples show that the dispersion curves obtained from the present model agree with the exact solutions for a range of wavelengths. Detailed numerical simulations are provided to illustrate graphically the phase and group velocities. Such illustrations allow the identification and comparison of the effects of the unit cell size, wave number and incident angle. It was observed that, as the incident angle increases, the dimensionless quasi-longitudinal phase velocity increases, and the dimensionless quasi-shear phase velocity decreases. In addition, the phase and group velocities decrease as the size of the unit cell increases. The frequency band structure, as a function of the wave-vector components is calculated.

A summary of observed seismic surface wave dispersion

1962 ◽  
Vol 52 (1) ◽  
pp. 81-86
Author(s):  
Jack Oliver
Keyword(s):  
Surface Wave ◽  
Present State ◽  
Rayleigh Waves ◽  
Wave Dispersion ◽  
Surface Wave Dispersion ◽  
Phase And Group Velocities ◽  
Group Velocities

Abstract Two sets of curves relating phase and group velocities of Love and Rayleigh waves to periods summarize our present state of knowledge on seismic surface wave dispersion. Periods range from about one second to one hour, and velocities from about one kilometer per second to about eight kilometers per second.

Preparation of Electron Transparent Metal-Matrix Composites

1968 ◽  
Vol 26 ◽  
pp. 334-335 ◽  
Author(s):  
M. R. Pinnel ◽  
A. Lawley
Keyword(s):  
Stainless Steel ◽  
Load Transfer ◽  
Volume Fraction ◽  
Steel Wire ◽  
Initial Step ◽  
Interfacial Region ◽  
Matrix Composites ◽  
Specific Test ◽  
The Matrix ◽  
The One

Numerous phenomenological descriptions of the mechanical behavior of composite materials have been developed. There is now an urgent need to study and interpret deformation behavior, load transfer, and strain distribution, in terms of micromechanisms at the atomic level. One approach is to characterize dislocation substructure resulting from specific test conditions by the various techniques of transmission electron microscopy. The present paper describes a technique for the preparation of electron transparent composites of aluminum-stainless steel, such that examination of the matrix-fiber (wire), or interfacial region is possible. Dislocation substructures are currently under examination following tensile, compressive, and creep loading. The technique complements and extends the one other study in this area by Hancock.The composite examined was hot-pressed (argon atmosphere) 99.99% aluminum reinforced with 15% volume fraction stainless steel wire (0.006″ dia.).Foils were prepared so that the stainless steel wires run longitudinally in the plane of the specimen i.e. the electron beam is perpendicular to the axes of the wires. The initial step involves cutting slices ∼0.040″ in thickness on a diamond slitting wheel.

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