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CONTENTS
Volume 13, Number 2, April 2024
 

Abstract
In this paper, we will analyse the thermo-elastic behavior of the plate element of a structure arranged in a climatically aggressive environment (extreme temperature), we use a refined four-variable thick plate theory to take the shear effect into consideration, the proposed theory less computationally expensive and more accurate so that it incorporates the shear effect into the formulation. The plate is assumed to be simply supported on its four edges, so exact (closed-form) solutions are found according to the Navier expansion, and the governing stability equations and associated boundary conditions of the problem are obtained via the virtual works principle. The plate studied is made of laminated composite materials, so a parametric study is needed to see the effect of different types of parameters and coupling on the critical temperature value causing thermo-elastic instability of the plate and also on the natural frequency of free vibration, as well as for other parameters such as anisotropy, slenderness and aspect ratio of the plate and finally the lamination angle. Numerical results are obtained for specially orthotropic and antisymmetrical plates and are compared with those obtained by other theories in the literature to validate the analysis approach used.

Key Words
buckling; composite material; free vibration; instability; laminated plate; Navier series; thermal load

Address
H. Mataich, A. El Amrani and B. El Amrani: Laboratory of Mathematics, Modeling and Applied Physics, High Normal School, Sidi Mohamed Ben Abdellah University, 30040 Fez, Morocco

Abstract
This paper introduces an improved shear deformation theory for analyzing the buckling behavior of functionally graded plates subjected to varying temperatures. The transverse shear strain functions employed satisfy the stress-free condition on the plate surfaces without requiring shear correction factors. The material properties and thermal expansion coefficient of the porous functionally graded plate are assumed temperature-dependent and exhibit continuous variation throughout the thickness, following a modified power-law distribution based on the volume fractions of the constituents. Moreover, the study considers the influence of porosity distribution on the buckling of the functionally graded plates. Thermal loads are assumed to have uniform, linear, and nonlinear distributions through the thickness. The obtained results, considering the effect of porosity distribution, are compared with alternative solutions available in the existing literature. Additionally, this study provides comprehensive discussions on the influence of various parameters, emphasizing the importance of accounting for the porosity distribution in the buckling analysis of functionally graded plates.

Key Words
buckling behavior; FGM plate; porosity distribution; thermal expansion

Address
Abdelhak Zohra: Civil Engineering Department, University Center of Relizane, Algeria; Laboratory of Geomatics and Sustainable Development, University of Tiaret, Algeria
Benferhat Rabia. Hassaine Daouadji Tahar: Civil Engineering Department, University of Tiaret, Algeria; Laboratory of Geomatics and Sustainable Development, University of Tiaret, Algeria

Abstract
In this paper, an improved theoretical interfacial stress analysis is presented for simply supported composite aluminum- sandwich honeycomb beam strengthened by imperfect FGM plateusing linear elastic theory. The adherend shear deformations have been included in the present theoretical analyses by assuming a linear shear stress through the thickness of the adherends, while all existing solutions neglect this effect. Remarkable effect of shear deformations of adherends has been noted in the results. It is shown that both the sliding and the shear stress at the interface are influenced by the material and geometry parameters of the composite beam. This new solution is intended for applicationto composite beams made of all kinds of materials bonded with a thin plate. Finally, numerical comparisons between the existing solutions and the present new solution enable a clear appreciation of the effects of various parameters.

Key Words
adhesive bonding; aluminum-sandwich honeycomb composite beam; composite plate; interfacial stresses; shear lag effect; slip; strengthening

Address
Bensatallah Tayeb, Rabahi Abderezak and Tahar Hassaine Daouadji: Laboratory of Geomatics and Sustainable Development, University of Tiaret, Algeria; Department of Civil Engineering, Ibn Khaldoun University of Tiaret, Algeria

Abstract
The problem considered in this theoretical paper is the delamination of a multilayered inhomogeneous beam structure that has viscoelastic behaviour under angle of twist, horizontal and vertical displacements which vary smoothly with time according to prescribed laws. The cross-section of the beam is a rectangle. The layers are made of different materials which are smoothly inhomogeneous along the length of the beam. The beam under consideration represents statically undetermined structure since it is clamped in its two ends. The problem of the strain energy release rate is solved. For this purpose, the strain energy stored in the beam structure is analyzed. In order to verify the solution obtained, the strain energy release rate is found also analyzing the time-dependent compliances of the beam under prescribed angle of twist and displacements. A parametric investigation is carried-out by applying the solution obtained. Special attention is paid to the effect of the parameters which control the variation of the angle of twist and the displacements with time on the strain energy release rate.

Key Words
delamination; displacement; inhomogeneous beam; multilayered material; twist

Address
Victor I. Rizov: Department of Technical Mechanics, University of Architecture, Civil Engineering and Geodesy,
1 Chr. Smirnensky Blvd., 1046-Sofia, Bulgaria

Abstract
In the present paper, thermal buckling characteristics of functionally graded rectangular plates made of porous material that are integrated with surface-bonded piezoelectric actuators subjected to the combined action of thermal load and constant applied actuator voltage are investigated by utilizing a Navier solution method. The uniform temperature rise loading is considered. Thermomechanical material properties of FGM plates are assumed to be temperature independent and supposed to vary through thickness direction of the constituents according to powerlaw distribution (P-FGM) which is modified to approximate the porous material properties with even and uneven distributions of porosities phases. The governing differential equations of stability for the piezoelectric FGM plate are derived based on higher order shear deformation plate theory. Influences of several important parameters on the critical thermal buckling temperature are investigated and discussed in detail.

Key Words
functionally graded materials; higher order shear deformation plate theory; piezoelectric; porosities; Thermal buckling

Address
Mokhtar Ellali: Smart Structures Laboratory, University of Ain Témouchent-Belhadj Bouchaib,46000, Algeria
Khaled Amara: Department of Civil Engineering, University of Ain Témouchent-Belhadj Bouchaib,46000, Algeria; Department of Civil Engineering, University Tahri Mohamed of Bechar, Bechar 08000, Algeria
Mokhtar Bouazza: Laboratory of Materials and Hydrology (LMH), University of Sidi Bel Abbes, Sidi Bel Abbes 22000, Algeria

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