• Earthquakes and Structures
• /
• v.4 no.1
• /
• pp.1-10
• /
• 2013

The present investigation deals with the analysis of wave motion in the layer of an anisotropic, initially stressed, fiber reinforced thermoelastic medium. Secular equations for symmetric and skew-symmetric modes of wave propagation in completely separate terms are derived. The amplitudes of displacements and temperature distribution were also obtained. Finally, the numerical solution was carried out for Cobalt and the dispersion curves, amplitudes of displacements and temperature distribution for symmetric and skew-symmetric wave modes are presented to evince the effect of anisotropy. Some particular cases are also deduced.

• Bulletin of the Korean Mathematical Society
• /
• v.35 no.1
• /
• pp.63-74
• /
• 1998

Our study is dedicated to the the proof of uniqueness of solution of initially boundary value problem in Elastodynamics of initially stressed bodies with voids. This proof is obtained without recourse either to an energy conservation law or to any boundedness assumptions on the elastic coefficients.

• Steel and Composite Structures
• /
• v.23 no.3
• /
• pp.251-261
• /
• 2017

In this paper, thermal effect on the vibration and stability of initially stressed sandwich plates with functionally graded material (FGM) face sheets is analyzed. Material properties of FGM face sheet are graded continuously in the thickness direction. The variation of FGM properties assumes a simple power law distribution in terms of the volume fractions of the constituents. The governing equations of arbitrarily initially-stressed sandwich plates including the effects of transverse shear deformation and rotary inertia are derived. The initial stress is taken to be a combination of a uniaxial extensional stress and a pure bending stress in the examples. The eigenvalue problems are formed to study the vibration and buckling characteristics of simple supported initially stressed FGM/metal/FGM plates. The effects of volume fraction index, temperature rise, initial stress and layer thickness of metal on the natural frequencies and buckling loads are investigated. The results reveal that the volume fraction index, initial stresses and layer thickness of metal have significant influence on the vibration and stability of sandwich plates with FGM face sheets.

• Steel and Composite Structures
• /
• v.20 no.5
• /
• pp.1103-1117
• /
• 2016

The present investigation is to study the plane problem in initially stressed thermoelastic half-space with voids due to thermal source. Lord-Shulman (Lord and Shulman 1967) theory of thermoelasticity with one relaxation time has been used to investigate the problem. A particular type of thermal source has been taken as an application of the approach. Finite element technique has been used to solve the problem. The components of displacement, stress, temperature change and volume fraction field are computed numerically. The resulting quantities are depicted graphically for different values of initial stress parameter. The relaxation time and the initial stress parameter have a significant effect on all distributions.

• Geomechanics and Engineering
• /
• v.16 no.2
• /
• pp.169-176
• /
• 2018

An attempt has been made here to study the propagation of SH-type surface waves in an elastic medium, which is initially stressed and heterogeneous and has a point source inside the medium. The upper portion of the composite medium is a sandy layer. It is situated on an initially stressed heterogeneous half-space, whose density, rigidity and internal friction are function of depth. The analysis has been carried out by using Fourier transform and Green's function approach. The phase velocity has been investigated for several particular situations. It has been shown that the results of the study agree with those the case of Love wave propagation in a homogeneous medium in the absence of the sandy layer, when the initial stress is absent. In order to illustrate the validity of the analysis presented here, the derived analytical expression has been computed numerically, by considering an illustrative example and the variances of the concerned physical variables have been presented graphically. It is observed that the velocity of shear wave is amply influenced by the initial stress and heterogeneity parameters and the presence of the sandy layer. The study has an important bearing on investigations of different problems in the earth's interior and also in seismological studies.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.18 no.1
• /
• pp.150-159
• /
• 2014

A simplified method for the calculation of buckling and vibrational characteristics of initially stressed rectangular plate and antisymmetric angle-ply laminated plates is presented in this paper using the natural frequencies under unloading state. The equation of motion of rectangular plate with two opposite edges simply supported is investigated on the basis of Rayleigh-Ritz method and Mindlin plate theory with effect of the curvature term. The relationships of the non-dimensional natural frequencies with initial stresses the coeffcients of critical buckling and the boundaries of the dynamic principal instability region can be characterized by the non-dimensional natureal frequencies under unloading state. Numerical examples are presented to verify the simplified equations and to illustrate potential applications of the analysis.

• Journal of Mechanical Science and Technology
• /
• v.18 no.5
• /
• pp.733-741
• /
• 2004

Vibration behavior of an initially stressed beam on discretely spaced multiple elastic supports has been studied and a theoretical formulation of the system is derived using the variational principle. Unlike beams on an elastic foundation, discretely spaced supports can distort the beam mode shapes when the supports have rather large stiffness, i.e. usually expected beam modes cannot be obtained, but rather irregular mode shapes are observed. Conversely, irregular modes can be recovered by changing initial stress. Since support location is closely associated with the dynamic characteristics, this work also discusses eigenvalue sensitivity with respect to the support position and some numerical examples are investigated to illustrate the above findings.

• Smart Structures and Systems
• /
• v.17 no.2
• /
• pp.327-345
• /
• 2016

The existence of SH-wave in a piezomagnetic layer overlying an initially stressed orthotropic half-space is investigated. The coupled of differential equations are solved for piezomagnetic layer overlying an orthotropic elastic half-space. The general dispersion equation has been derived for both magnetically open circuit and magnetically closed circuits under the four types of boundary conditions. In the absence of the piezomagnetic properties, initial stress and orthotropic properties of the medium, the dispersion equations reduce to classical Love equation. The SH-wave velocity has been calculated numerically for both magnetically open circuit and closed circuits. The effect of initial stress and magnetic permeability are illustrated by graphs in both the cases. The velocity of SH-wave decreases with the increment of wave number.

• Structural Engineering and Mechanics
• /
• v.69 no.2
• /
• pp.121-129
• /
• 2019

The present study investigates the propagation of shear waves in a composite structure comprised of imperfectly bonded piezoelectric layer with a micropolar half space. Piezoelectric layer is considered to be initially stressed. Micropolar theory of elasticity has been employed which is most suitable to explain the size effects on small length scale. The general dispersion equations for the existence of waves in the coupled structure are obtained analytically in the closed form. Some particular cases have been discussed and in one particular case the dispersion relation is in well agreement to the classical-Love wave equation. The effects of various parameters viz. initial stress, interfacial imperfection and micropolarity on the phase velocity are obtained for electrically open and mechanically free system. Numerical computations are carried out and results are depicted graphically to illustrate the utility of the problem. The phase velocity of the shear waves is found to be influenced by initial stress, interface imperfection and the presence of micropolarity in the elastic half space. The theoretical results obtained are useful for the design of high performance surface acoustic devices.

• Steel and Composite Structures
• /
• v.20 no.4
• /
• pp.833-849
• /
• 2016

Pre-stressing of existing structures using steel cables, FRP cables or FRP laminates has been successfully tried in the past. Retrofitting of beams using pre-stressed laminates does not utilize the full strength of the FRP due to de-bonding of the laminates before the fibre fracture. In the present study attempt has been made to overcome this problem by replacing the FRP laminates by the FRP sheets. In the present paper the effect of initial damage level and pre-stress level on strength, stiffness, cracking behaviour and failure mode of girders retrofitted using pre-stressed CFRP sheets has been studied. The results indicate that rehabilitation of initially damaged girders by bonding pre-stressed CFRP sheets improves the flexural behaviour of beams appreciably. However, it has been observed that with increase in pre-stressing force the load carrying capacity of the girders increases up to a particular level up to which the mode of failure is fibre fracture. Thereafter, the mode of failure shifts from fibre fracture to de-bonding and there is no appreciable increase in load carrying capacity with further increase in pre-stressing force.