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Youcef Beldjelili,Abdelouahed Tounsi,S.R. Mahmoud 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.18 No.4
The hygro-thermo-mechanical bending behavior of sigmoid functionally graded material (S-FGM) plate resting on variable two-parameter elastic foundations is discussed using a four-variable refined plate theory. The material characteristics are distributed within the thickness direction according to the two power law variation in terms of volume fractions of the constituents of the material. By employing a four variable refined plate model, both a trigonometric distribution of the transverse shear strains within the thickness and the zero traction boundary conditions on the top and bottom surfaces of the plate are respected without utilizing shear correction factors. The number of independent variables of the current formulation is four, as against five in other shear deformation models. The governing equations are deduced based on the four-variable refined plate theory incorporating the external load and hygro-thermal influences. The results of this work are compared with those of other shear deformation models. Various numerical examples introducing the influence of power-law index, plate aspect ratio, temperature difference, elastic foundation parameters, and side-to-thickness ratio on the static behavior of S-FGM plates are investigated.
A novel refined plate theory for stability analysis of hybrid and symmetric S-FGM plates
Fouad Bourada,Khaled Amara,Abdelmoumen A. Bousahla,Abdelouahed Tounsi,S. R. Mahmoud 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.6
In this paper, buckling analysis of hybrid functionally graded plates using a novel four variable refined plate theory is presented. In this theory the distribution of transverse shear deformation is parabolic across the thickness of the plate by satisfying the surface conditions. Therefore, it is unnecessary to use a shear correction factor. The variations of properties of the plate through the thickness are according to a symmetric sigmoid law (symmetric S-FGM). The principle virtual works is used herein to extract equilibrium equations. The analytical solution is determined using the Navier method for a simply supported rectangular plate subjected to axial forces. The precision of this theory is verified by comparing it with the various solutions available in the literature.
Matouk, Hakima,Bousahla, Abdelmoumen Anis,Heireche, Houari,Bourada, Fouad,Bedia, E.A. Adda,Tounsi, Abdelouahed,Mahmoud, S.R.,Tounsi, Abdeldjebbar,Benrahou, K.H. Techno-Press 2020 Advances in nano research Vol.8 No.4
In the current research, the free vibrational behavior of the FG nano-beams integrated in the hygro-thermal environment and reposed on the elastic foundation is investigated using a novel integral Timoshenko beam theory (ITBT). The current model has only three variables unknown and requires the introduction of the shear correction factor because her uniformed variation of the shear stress through the thickness. The effective properties of the nano-beam vary according to power-law and symmetric sigmoid distributions. Three models of the hygro-thermal loading are employed. The effect of the small scale effect is considered by using the nonlocal theory of Eringen. The equations of motion of the present model are determined and resolved via Hamilton principle and Navier method, respectively. Several numerical results are presented thereafter to illustrate the accuracy and efficiency of the actual integral Timoshenko beam theory. The effects of the various parameters influencing the vibrational responses of the P-FG and SS-FG nano-beam are also examined and discussed in detail.
S. R. Mahmoud,E.I. Ghandourah,A.H. Algarni,M.A. Balubaid,Abdelouahed Tounsi,Abdeldjebbar Tounsi,Fouad Bourada 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.4
This paper presents an analytical hyperbolic theory based on the refined shear deformation theory for mechanical stability analysis of the simply supported advanced composites plates (exponentially, sigmoidal and power-law graded) under triangular, trapezoidal and uniform uniaxial and biaxial loading. The developed model ensures the boundary condition of the zero transverse stresses at the top and bottom surfaces without using the correction factor as first order shear deformation theory. The mathematical formulation of displacement contains only four unknowns in which the transverse deflection is divided to shear and bending components. The current study includes the effect of the geometric imperfection of the material. The modeling of the micro-void presence in the structure is based on the both true and apparent density formulas in which the porosity will be dense in the mid-plane and zero in the upper and lower surfaces (free surface) according to a logarithmic function. The analytical solutions of the uniaxial and biaxial critical buckling load are determined by solving the differential equilibrium equations of the system with the help of the Navier’s method. The correctness and the effectiveness of the proposed HyRPT is confirmed by comparing the results with those found in the open literature which shows the high performance of this model to predict the stability characteristics of the FG structures employed in various fields. Several parametric analyses are performed to extract the most influenced parameters on the mechanical stability of this type of advanced composites plates.
On the stability of isotropic and composite thick plates
S. R. Mahmoud,Abdelouahed Tounsi 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.33 No.4
This proposed project presents the bi-axial and uni-axial stability behavior of laminated composite plates based on an original three variable "refined" plate theory. The important "novelty" of this theory is that besides the inclusion of a cubic distribution of transverse shear deformations across the thickness of the structure, it treats only three variables such as conventional plate theory (CPT) instead five as in the well-known theory of "first shear deformation" (FSDT) and theory of "higher order shear deformation" (HSDT). A "shear correction coefficient" is therefore not employed in the current formulation. The computed results are compared with those of the CPT, FSDT and exact 3D elasticity theory. Good agreement is demonstrated and proved for the present results with those of "HSDT" and elasticity theory.
Nahed S. Hussein,F.S. Bayones,S.R. Mahmoud 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.1
The present investigation is concerned with a study effect of magnetic field and nonhomogenous on the elastic stresses in rotating orthotropic infinite circular cylinder. A certain boundary conditions closed form stress fields solutions are obtained for rotating orthotropic cylinder under initial magnetic field with constant thickness for three cases: (1) Solid cylinder, (2) Cylinder with a circular hole at the center, (3) Cylinder mounted on a circular rigid shaft. Analytical expressions for the components of the displacement and stress fields in different cases are obtained. The effect of rotation and magnetic field and non-homogeneity on the displacement and stress fields are studied. Numerical results are illustrated graphically for each case. The effects of rotating and magnetic field and non-homogeneity are discussed.
Hussein, Nahed S.,Bayones, F.S.,Mahmoud, S.R. Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.1
The present investigation is concerned with a study effect of magnetic field and non-homogenous on the elastic stresses in rotating orthotropic infinite circular cylinder. A certain boundary conditions closed form stress fields solutions are obtained for rotating orthotropic cylinder under initial magnetic field with constant thickness for three cases: (1) Solid cylinder, (2) Cylinder with a circular hole at the center, (3) Cylinder mounted on a circular rigid shaft. Analytical expressions for the components of the displacement and stress fields in different cases are obtained. The effect of rotation and magnetic field and non-homogeneity on the displacement and stress fields are studied. Numerical results are illustrated graphically for each case. The effects of rotating and magnetic field and non-homogeneity are discussed.
Elastic shell model: Effect of Young's Modulus on the vibration of double-walled CNTs
Hussain, Muzamal,Asghar, Sehar,Khadimallah, Mohamed Amine,Ayed, Hamdi,Banoqitah, Essam Mohammed,Loukil, Hassen,Ali, Imam,Mahmoud, S.R.,Tounsi, Abdelouahed Techno-Press 2022 Advances in concrete construction Vol.13 No.6
In this paper, vibrational attributes of double-walled carbon nanotubes (CNTs) has been studied based upon nonlocal elastic shell theory. The implication of small scale is being perceived by establishing nonlocal Love shell model. The wave propagation approach has been operated to frame the governing equations as eigen value system. The comparison of local and nonlocal model has been overtly explored by means of scaling parameter. An appropriate selection of material properties and nonlocal parameter has been considered. The influence of changing mechanical parameter Young's modulus has been studied in detail. The dominance of end condition via nonlocal parameter is explained graphically. The results generated furnish the evidence regarding applicability of nonlocal shell model and also verified by earlier published literature.
Hadj Henni Abdelaziz,Mohamed Ait Amar Meziane,Abdelmoumen Anis Bousahla,Abdelouahed Tounsi,S.R. Mahmoud,Afaf S. Alwabli 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.25 No.6
In this research, a simple hyperbolic shear deformation theory is developed and applied for the bending, vibration and buckling of powerly graded material (PGM) sandwich plate with various boundary conditions. The displacement field of the present model is selected based on a hyperbolic variation in the in-plane displacements across the plate‟s thickness. By splitting the deflection into the bending and shear parts, the number of unknowns and equations of motion of the present formulation is reduced and hence makes them simple to use. Equations of motion are obtained from Hamilton‟s principle. Numerical results for the natural frequencies, deflections and critical buckling loads of several types of powerly graded sandwich plates under various boundary conditions are presented. The accuracy of the present formulation is demonstrated by comparing the computed results with those available in the literature. As conclusion, this theory is as accurate as other theories available in the literature and so it becomes more attractive due to smaller number of unknowns.
Moussa Bellal,Habib Hebali,Houari Heireche,Abdelmoumen Anis Bousahla,Abdeldjebbar Tounsi,Fouad Bourada,S.R. Mahmoud,E.A. Adda Bedia,Abdelouahed Tounsi 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.5
In the present work, the buckling behavior of a single-layered graphene sheet (SLGS) embedded in visco-Pasternak’s medium is studied using nonlocal four-unknown integral model. This model has a displacement field with integral terms which includes the effect of transverse shear deformation without using shear correction factors. The visco-Pasternak’s medium is introduced by considering the damping effect to the classical foundation model which modeled by the linear Winkler’s coefficient and Pasternak’s (shear) foundation coefficient. The SLGS under consideration is subjected to compressive in- plane edge loads per unit length. The influences of many parameters such as nonlocal parameter, geometric ratio, the visco-Pasternak’s coefficients, damping parameter, and mode numbers on the buckling response of the SLGSs are studied and discussed.