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Naceri M.,University Djilali Liabes | Zidour M.,University Djilali Liabes | Zidour M.,Université Ibn Khaldoun | Semmah A.,University Djilali Liabes | And 4 more authors.
Journal of Applied Physics | Year: 2011

This paper develops a model that analyzes the wave propagation in armchair single-walled carbon nanotubes (SWCNTs) under thermal environment. The effect of a small length scale is incorporated in the formulations using nonlocal Levinson beam model. Unlike Timoshenko beam theory, Levinson beam theory satisfies zero traction boundary conditions on the upper and lower surface of the structures, so there is no need to use a shear correction factor. The equivalent Young's modulus and shear modulus for armchair SWCNT are derived using an energy-equivalent model. Results indicate significant dependence of natural frequencies on the temperature change as well as the chirality of armchair carbon nanotube. These findings are important in mechanical design considerations of devices that use carbon nanotubes. © 2011 American Institute of Physics.


Larbi L.O.,University Djilali Liabes | Kaci A.,University Djilali Liabes | Houari M.S.A.,University Djilali Liabes | Houari M.S.A.,University Of Mascaraa | Tounsi A.,University Djilali Liabes
Mechanics Based Design of Structures and Machines | Year: 2013

In this article, an efficient shear deformation beam theory based on neutral surface position is developed for bending and frees vibration analysis of functionally graded beams. The theory accounts for hyperbolic distribution of the transverse shear strains and satisfies the zero traction boundary conditions on the surfaces of the beam without using shear correction factors. The neutral surface position for a functionally graded beam in which its material properties vary in the thickness direction is determined. Based on the present higher order shear deformation beam theory and the neutral surface concept, the equations of motion are derived from Hamilton's principle. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions. It can be concluded that the present theory is not only accurate but also simple in predicting the bending and vibration behavior of functionally graded beams. © 2013 Taylor & Francis Group, LLC.


Bourada M.,University Djilali Liabes | Tounsi A.,University Djilali Liabes | Houari M.S.A.,University Djilali Liabes | Houari M.S.A.,University Of Mascaraa | Adda Bedia E.A.,University Djilali Liabes
Journal of Sandwich Structures and Materials | Year: 2012

The novelty of this paper is the use of a new four-variable refined plate theory for thermal buckling analysis of functionally graded material (FGM) sandwich plates. Unlike any other theory, the present new theory is variationally consistent and gives four governing equations. The number of unknown functions involved is only four, as against five in case of other shear deformation theories. In addition, the theory, which has strong similarity with classical plate theory in many aspects, accounts for a quadratic variation of the transverse shear strains across the thickness and satisfies the zero traction boundary conditions on the top and bottom surfaces of the plate without using shear correction factors. Material properties and thermal expansion coefficient of the sandwich plate faces are assumed to be graded in the thickness direction according to a simple power-law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and made of an isotropic material. The thermal loads are assumed as uniform, linear, and nonlinear temperature rises across the thickness direction. The effects of aspect and thickness ratios, gradient index, loading type, and sandwich plate type on the critical buckling are all discussed. © The Author(s) 2011.


Tounsi A.,University Djilali Liabes | Houari M.S.A.,University Djilali Liabes | Houari M.S.A.,University Of Mascaraa | Benyoucef S.,University Djilali Liabes | Adda Bedia E.A.,University Djilali Liabes
Aerospace Science and Technology | Year: 2013

A refined trigonometric shear deformation theory (RTSDT) taking into account transverse shear deformation effects is presented for the thermoelastic bending analysis of functionally graded sandwich plates. Unlike any other theory, the number of unknown functions involved is only four, as against five in case of other shear deformation theories. The theory presented is variationally consistent, does not require shear correction factor, the displacement components are expressed by trigonometric series representation through the plate thickness to develop a two-dimensional theory and gives rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress free surface conditions. The sandwich with homogeneous facesheet and FGM core is considered. Material properties of the present FGM core are assumed to vary according to a power law distribution in terms of the volume fractions of the constituents. The influences played by the transverse shear deformation, thermal load, plate aspect ratio, and volume fraction distribution are studied. Numerical results for deflections and stresses of functionally graded metal-ceramic plates are investigated. It can be concluded that the proposed theory is accurate and simple in solving the thermoelastic bending behavior of functionally graded plates. © 2011 Elsevier Masson SAS. All rights reserved.


Ahmed Houari M.S.,University Djilali Liabes | Ahmed Houari M.S.,University Of Mascaraa | Benyoucef S.,University Djilali Liabes | Mechab I.,University Djilali Liabes | And 3 more authors.
Journal of Thermal Stresses | Year: 2011

The thermoelastic bending analysis of functionally graded sandwich plates using the two-variable refined plate theory is presented in this paper. Unlike any other theory, the number of unknown functions involved is only four, as against five in case of other shear deformation theories. The theory presented is variationally consistent, has strong similarity with classical plate theory in many aspects, does not require shear correction factor, and gives rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress free surface conditions. The sandwich plate faces are assumed to have isotropic, two-constituent material distribution through the thickness, and the modulus of elasticity, Poisson's ratio of the faces, and thermal expansion coefficients are assumed to vary according to a power law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and made of an isotropic ceramic material. Several kinds of sandwich plates are used taking into account the symmetry of the plate and the thickness of each layer. The influences played by the transverse shear deformation, thermal load, plate aspect ratio, and volume fraction distribution are studied. Numerical results for deflections and stresses of functionally graded metal-ceramic plates are investigated. It can be concluded that the proposed theory is accurate and simple in solving the thermoelastic bending behavior of functionally graded plates. Copyright © Taylor & Francis Group, LLC.


Bouremana M.,University Djilali Liabes | Houari M.S.A.,University Djilali Liabes | Houari M.S.A.,University Of Mascaraa | Tounsi A.,University Djilali Liabes | And 2 more authors.
Steel and Composite Structures | Year: 2013

In this paper, a new first-order shear deformation beam theory based on neutral surface position is developed for bending and free vibration analysis of functionally graded beams. The proposed theory is based on assumption that the in-plane and transverse displacements consist of bending and shear components, in which the bending components do not contribute toward shear forces and, likewise, the shear components do not contribute toward bending moments. The neutral surface position for a functionally graded beam which its material properties vary in the thickness direction is determined. Based on the present new first-order shear deformation beam theory and the neutral surface concept together with Hamilton's principle, the motion equations are derived. To examine accuracy of the present formulation, several comparison studies are investigated. Furthermore, the effects of different parameters of the beam on the bending and free vibration responses of functionally graded beam are discussed. © 2013 Techno-Press, Ltd.


Meksi A.,University Djilali Liabes | Benyoucef S.,University Djilali Liabes | Houari M.S.A.,University Djilali Liabes | Houari M.S.A.,University Of Mascaraa | Tounsi A.,University Djilali Liabes
Structural Engineering and Mechanics | Year: 2015

In this work, a novel simple first-order shear deformation plate theory based on neutral surface position is developed for bending and free vibration analysis of functionally graded plates and supported by either Winkler or Pasternak elastic foundations. By dividing the transverse displacement into bending and shear parts, the number of unknowns and governing equations of the present theory is reduced, and hence, makes it simple to use. The governing equations are derived by employing the Hamilton's principle and the physical neutral surface concept. There is no stretching-bending coupling effect in the neutral surface-based formulation, and consequently, the governing equations and boundary conditions of functionally graded plates based on neutral surface have the simple forms as those of isotropic plates. Numerical results of present theory are compared with results of the traditional first-order and the other higher-order theories reported in the literature. It can be concluded that the proposed theory is accurate and simple in solving the static bending and free vibration behaviors of functionally graded plates. Copyright © 2015 Techno-Press, Ltd.


Hamidi A.,University Djilali Liabes | Zidi M.,University Djilali Liabes | Houari M.S.A.,University Djilali Liabes | Houari M.S.A.,University Of Mascaraa | Tounsi A.,University Djilali Liabes
Composites Part B: Engineering | Year: 2015

This article has been withdrawn at the request of the editor. The Publisher apologizes for any inconvenience this may cause.The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy. © 2015.


Bouiadjra M.B.,University Djilali Liabes | Ahmed Houari M.S.,University Djilali Liabes | Ahmed Houari M.S.,University Of Mascaraa | Tounsi A.,University Djilali Liabes
Journal of Thermal Stresses | Year: 2012

In this article, a four-variable refined plate theory is presented for buckling analysis of functionally graded plates. The theory, which has strong similarity with classical plate theory in many aspects, accounts for a quadratic variation of the transverse shear strains across the thickness and satisfies the zero traction boundary conditions on the top and bottom surfaces of the plate without using shear correction factors. A power law distribution is used to describe the variation of volume fraction of material compositions. Equilibrium and stability equations are derived based on the present theory. The non-linear governing equations are solved for plates subjected to simply supported boundary conditions. The thermal loads are assumed to be uniform, linear and non-linear distribution through-the-thickness. The influences of many plate parameters on buckling temperature difference will be investigated. It is noticed that the present refined plate theory can predict accurately the critical temperatures of simply supported functionally graded plates. © 2012 Copyright Taylor and Francis Group, LLC.


Merdaci S.,University Djilali Liabes | Tounsi A.,University Djilali Liabes | Houari M.S.A.,University Djilali Liabes | Houari M.S.A.,University Of Mascaraa | And 4 more authors.
Archive of Applied Mechanics | Year: 2011

Two refined displacement models, RSDT1 and RSDT2, are developed for a bending analysis of functionally graded sandwich plates. Unlike any other theory, the number of unknown functions involved is only four, as against five in case of other shear deformation theories. The developed models are variationally consistent, have strong similarity with classical plate theory in many aspects, do not require shear correction factor, and give rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress-free surface conditions. The accuracy of the analysis presented is demonstrated by comparing the results with solutions derived from other higher-order models. The functionally graded layers are assumed to have isotropic, two-constituent material distribution through the thickness, and the modulus of elasticity, Poisson's ratio of the faces, and thermal expansion coefficients are assumed to vary according to a power-law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and made of an isotropic ceramic material. Numerical results for deflections and stresses of functionally graded metal-ceramic plates are investigated. It can be concluded that the proposed models are accurate and simple in solving the bending behavior of functionally graded plates. © 2010 Springer-Verlag.

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