DSpace Repository :: Browsing by Author "Abdelhakim Bouhadra"

Browsing by Author "Abdelhakim Bouhadra"

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A New High Order Theory for Buckling Temperature Analysis of Functionally Graded Sandwich Plates Resting on Elastic Foundations
(2022-06-30) Abdelhakim Bouhadra
Using a high order theory (HSDT), this work presents a study of thermal buckling of functionally graded (FG) sandwich plates subjected to various temperature rises across their thickness and resting on a twoparameter elastic foundation. The mechanical properties of the FG sandwich plates are supposed to change gradually through the thickness according to a power law (P-FGM). The intermediate layer is homogeneous and made of a purely ceramic material. The principle of virtual works is used to obtain stability equations, and their solutions are obtained based on Navier’s solution technique. The obtained results are compared with other studies in the literature. Then, a parametric study is conducted to investigate the influence of geometric and mechanical characteristics such as the ratios of dimensions (width, length, and thickness), the material index (k), and the effect of the elastic foundation on the critical buckling temperature.
Assessment of the effect of the materials composition on the bending response of FG plates lying on two models of elastic foundations in thermo-hygro-mechanical environments
(2023-08-20) Abdelhakim Bouhadra
his study fulfils a thermo-hygro-mechanical analysis of the bending behavior of FG plates resting on different elastic foundation models. A quasi-3D high-order shear deformation theory with five unknowns is used herein to perform this analysis. The impact of shear deformation and stretching effect are included in the formulation of the used approach. The result of the change in material characteristics and the volumetric fraction of components on the bending response of FG plates in a thermo-hygro-mechanical environment is analyzed and discussed. The principle of virtual displacements is used to obtain the equilibrium equations, and the Navier-type solution is applied to solve the resulting equations. The results show that the increase in thermal load and moisture concentration causes a rapid deflection increase. Furthermore, the Winkler parameter influences the shear stresses more than the deflections.
Boundary conditions effect for buckling analysis of porous functionally graded nanobeam
(2020-11-09) Abdelhakim Bouhadra
This paper is concerned with the buckling behavior of 2D and quasi-3D problem of functionally graded nanobeam founded on high order shear deformation beams theory and made by two different types of porous distribution materials in Nano- and micro-scales. The used Quasi-3D formulation takes into account the transverse shear effect and uses only three variables. Both formulations do not include the correction factor that is required in the first shear deformation theory proposed by Timoshenko. Governing equations are derived using the principle of virtual work. Analytical resolutions for buckling of FG nanobeam are introduced under tow different boundary conditions, and the results obtained are compared to those proposed in literatures.
Buckling behaviors of FG porous sandwich plates with metallic foam cores resting on elastic foundation
(2020-12-30) Abdelhakim Bouhadra
The main objective of this paper is to study the effect of porosity on the buckling behavior of thick functionally graded sandwich plate resting on various boundary conditions under different in-plane loads. The formulation is made for a newly developed sandwich plate using a functional gradient material based on a modified power law function of symmetric and asymmetric configuration. Four different porosity distribution are considered and varied in accordance with material propriety variation in the thickness direction of the face sheets of sandwich plate, metal foam also is considered in this study on the second model of sandwich which containing metal foam core and FGM face sheets. New quasi-3D high shear deformation theory is used here for this investigate; the present kinematic model introduces only six variables with stretching effect by adopting a new indeterminate integral variable in the displacement field. The stability equations are obtained by Hamilton’s principle then solved by generalized solution. The effect of Pasternak and Winkler elastic foundations also including here. the present model validated with those found in the open literature, then the impact of different parameters: porosities index, foam cells distribution, boundary conditions, elastic foundation, power law index, ratio aspect, side-to-thickness ratio and different in-plane axial loads on the variation of the buckling behavior are demonstrated.
Combined effect of temperature dependent material properties and boundary conditions on non-linear thermal stability of porous FG beams
(2024-02-18) Abdelhakim Bouhadra
This paper presents an analytical formulation to investigate functionally graded porous beams’ nonlinear thermal buckling performance under various boundary conditions. The current model incorporates innovative cinematic techniques with the focus on the stretching effect and the iteration techniques. The material properties of the porous FG beams are temperature-dependent and vary according to a simple powerlaw distribution. The validity of the present theory’ results is confirmed by comparing them with those obtained by other researchers. The findings demonstrate that the critical buckling temperature in TD and TID ranges from 1.03 to 1.27% for a uniform distribution and 1 to 1.47% for linear and non-linear distributions. Conversely, for regular porosity variation, the critical buckling temperatures fluctuate between 0.99 and 1.74%, and between 0.99 and 1.59% for porosity variation. Furthermore, the influence of boundary conditions becomes more pronounced when the nonlinear temperature difference is high
Combined Effect of Thickness Stretching and Temperature‑Dependent Material Properties on Dynamic Behavior of Imperfect FG Beams Using Three Variable Quasi‑3D Model
(2022-09-23) Abdelhakim Bouhadra
Purpose The multi-step sequential infiltration technique or sintering process usually produces porosities in functionally graded structures. It is confirmed that the porosity significantly influences the static responses of FGM beams, but its influence on their thermodynamic response is still worth studying. Methods To highlight this influence, the dynamic behavior of simply-supported porous FG beams with effective temperaturedependent material properties is examined by using a novel integral three variable quasi-3D high-order shear deformation theory for the first time. Notably, different thermal gradients varying along the thickness are considered. The governing differential equations of motion have been established based on Hamilton’s principle and solved by employing the Naviertype closedform solution. Results The present theoretical results are validated with the existing literature, and excellent agreement is identified between the results. Besides, material temperature dependence, power-law index, porosity parameter, temperature rising, and slenderness ratio effects are discussed. Results show that dynamic behavior using temperature-dependent and independent material properties would produce different natural frequencies. With the rise of porosity, the natural frequency decreases significantly at high temperatures. Conclusions The beam with a higher slenderness ratio is more sensitive to the stretching effect. Finally, to improve the thermodynamic behavior of such structures, ceramic constituents with a lower thermal expansion coefficient would be recommended.
Combined influence of porosity and elastic foundation parameters on the bending behavior of advanced sandwich structures
(2022-12-06) Abdelhakim Bouhadra
Elastic bending of imperfect functionally graded sandwich plates (FGSPs) laying on the Winkler-Pasternak foundation and subjected to sinusoidal loads is analyzed. The analyses have been established using the quasi-3D sinusoidal shear deformation model. In this theory, the number of unknowns is condensed to only five unknowns using integral-undefined terms without requiring any correction shear factor. Moreover, the current constituent material properties of the middle layer is considered homogeneous and isotropic. But those of the top and bottom face sheets of the graded porous sandwich plate (FGSP) are supposed to vary regularly and continuously in the direction of thickness according to the trigonometric volume fraction’s model. The corresponding equilibrium equations of FGSPs with simply supported edges are derived via the static version of the Hamilton’s principle. The differential equations of the system are resolved via Navier’s method for various schemes of FGSPs. The current study examine the impact of the material index, porosity, side-to-thickness ratio, aspect ratio, and the WinklerPasternak foundation on the displacements, axial and shear stresses of the sandwich structure.
Combined influence of variable distribution models and boundary conditions on the thermodynamic behavior of FG sandwich plates lying on various elastic foundations
(2023-12-04) Abdelhakim Bouhadra
The present research investigates the thermodynamically bending behavior of FG sandwich plates, laying on the Winkler/Pasternak/Kerr foundation with various boundary conditions, subjected to harmonic thermal load varying through thickness. The supposed FG sandwich plate has three layers with a ceramic core. The constituents’ volume fractions of the lower and upper faces vary gradually in the direction of the FG sandwich plate thickness. This variation is performed according to various models: a Power law, Trigonometric, Viola-Tornabene, and the Exponential model, while the core is constantly homogeneous. The displacement field considered in the current work contains integral terms and fewer unknowns than other theories in the literature. The corresponding equations of motion are derived based on Hamilton’s principle. The impact of the distribution model, scheme, aspect ratio, side-to-thickness ratio, boundary conditions, and elastic foundations on thermodynamic bending are examined in this study. The deflections obtained for the sandwich plate without elastic foundations have the lowest values for all boundary conditions. In addition, the minimum deflection values are obtained for the exponential volume fraction law model. The sandwich plate’s non-dimensional deflection increases as the aspect ratio increases for all distribution models.
Coupled effect of variable Winkler–Pasternak foundations on bending behavior of FG plates exposed to several types of loading
(2022-07-15) Abdelhakim Bouhadra
This study attempts to shed light on the coupled impact of types of loading, thickness stretching, and types of variation of Winkler–Pasternak foundations on the flexural behavior of simply- supported FG plates according to the new quasi– 3D high order shear deformation theory, including integral terms. A new function sheep is used in the present work. In particular, both Winkler and Pasternak layers are non-uniform and vary along the plate length direction. In addition, the interaction between the loading type and the variation of Winkler–Pasternak foundation parameters is considered and involved in the governing equilibrium equations. Using the virtual displacement principle and Navier’s solution technique, the numerical results of nondimensional stresses and displacements are computed. Finally, the non-dimensional formulas’ results are validated with the existing literature, and excellent agreement is detected between the results. More importantly, several complementary parametric studies with the effect of various geometric and material factors are examined. The present analytical model is suitable for investigating the bending of simply-supported FGM plates for special technical engineering applications.
Effect of Phase Contrast and Geometrical Parameters on Bending Behavior of Sandwich Beams with FG Isotropic Face Sheets
(2022-10-28) Abdelhakim Bouhadra
Our work is to study the bending behavior of sandwich beams with functional gradient by constituting an isotropic material whose material properties vary smoothly in the z direction only (FGM), where the central layer presents purely a homogeneous and isotropic ceramic. The mechanical properties of FG sandwich beams are assumed to be progressive in thickness according to a power law (P-FGM). Generally, the principle of virtual works is used to obtain the equilibrium equations, and their solutions are obtained based on Navier's solution technique. The present model is based on a shear deformation theory of 2D and 3D beams which contains four unknowns to extract the equilibrium equations of FG sandwich beams. In addition, analytical solutions for bending are used and numerical models are presented to verify the accuracy of the present theory. All the results obtained show that the stiffness of the FG beam decreases as a function of the increase in the volume fraction index k, leading to an increase in the deflections. However, FG beams become flexible by increasing the proportion of the metal to the ceramic part. Furthermore, the influences of material volume fraction index, layer thickness ratio, side-to-height ratio, and the effect of the phase contrast, on the deflections, normal and shear stress of simply supported sandwich FG beams are taken into investigation and discussed in detail. Finally, all our results obtained are in agreement with other previous theoretical works
Effect of variable volume fraction distribution and geometrical parameters on the bending behavior of sandwich plates with FG isotropic face sheets
(2023-03-23) Abdelhakim Bouhadra
This article analyzes the bending behavior of functionally graded sandwich plate structures submitted to sinusoidal loads using the hyperbolic quasi- 3D shear deformation plate theory. In this theory, the number of unknowns is reduced from six to only five unknowns using an undefined integral without needing any shear correction factor. Furthermore, the effective constituent material properties of the upper and lower layers of the functionally graded sandwich plate are assumed to vary smoothly and continuously only in the thickness direction. In contrast, the core layer is still homogeneous and isotropic. The governing equilibrium equations of simply supported functionally graded sandwich plates are derived using the principle of virtual displacement. Their analytical solution is obtained using Navier’s technique for various schemas of functionally graded sandwich plates. The effects of the power law index, side-to-thickness ratio, and aspect ratio on the bending behavior are investigated.
Effects of hygro-thermo-mechanical conditions on the buckling of FG sandwich plates resting on elastic foundations
(2020-03-14) Abdelhakim Bouhadra
In this research work, the hygrothermal and mechanical buckling responses of simply supported FG sandwich plate seated on Winkler-Pasternak elastic foundation are investigated using a novel shear deformation theory. The current model take into consideration the shear deformation effects and ensures the zero shear stresses on the free surfaces of the FG-sandwich plate without requiring the correction factors “Ks”. The material properties of the faces sheets of the FG-sandwich plate are assumed varies as power law function “P-FGM” and the core is isotropic (purely ceramic). From the virtual work principle, the stability equations are deduced and resolved via Navier model. The hygrothermal effects are considered varies as a nonlinear, linear and uniform distribution across the thickness of the FG-sandwich plate. To check and confirm the accuracy of the current model, a several comparison has been made with other models found in the literature. The effects the temperature, moisture concentration, parameters of elastic foundation, side-to-thickness ratio, aspect ratio and the inhomogeneity parameter on the critical buckling of FG sandwich plates are also investigated.
Hygro-thermo-mechanical bending response of FG plates resting on elastic foundations
(2020-11-02) Abdelhakim Bouhadra
The aim of this work is to study the hygro-thermo-mechanical bending responses of simply supported FG plate resting on a Winkler-Pasternak elastic foundation. The effect transverse shear strains is taken into account in which the zero transverse shear stress condition on the top and bottom surfaces of the plate is ensured without using any shear correction factors. The developed model contains only four unknowns variable which is reduced compared to other HSDTs models. The material properties of FG-plate are supposed to vary across the thickness of the plate according to power-law mixture. The differential governing equations are derived based on the virtual working principle. Numerical outcomes of bending analysis of FG plates under hygro-thermo-mechanical loads are performed and compared with those available in the literature. The effects of the temperature, moisture concentration, elastic foundation parameters, shear deformation, geometrical parameters, and power-law-index on the dimensionless deflections, axial and transverse shear stresses of the FG-plate are presented and discussed.
Impact of the homogenization models on the thermoelastic response of FG plates on variable elastic foundation
(2020-05-23) Abdelhakim Bouhadra
This paper presents a theoretical investigation on the response of the thermo-mechanical bending of FG plate on variable elastic foundation. A quasi-3D higher shear deformation theory is used that contains undetermined integral forms and involves only four unknowns to derive. The FG plates are supposed simply supported with temperature-dependent material properties and subjected to nonlinear temperature rise. Various homogenization models are used to estimate the effective material properties such as temperature-dependent thermoelastic properties. Equations of motion are derived from the principle of virtual displacements and Navier’s solution is used to solve the problem of simply supported plates. Numerical results for deflections and stresses of FG plate with temperature-dependent material properties are investigated. It can be concluded that the proposed theory is accurate and simple in solving the thermoelastic bending behavior of FG thick plates.
IMPACT OF THE SHEAR AND THICKNESS STRETCHING EFFECTS ON THE FREE VIBRATIONS OF ADVANCED COMPOSITE PLATES
(2023) Abdelhakim Bouhadra
Quasi-3D high-order shear deformation theories (HSDT) are often more effective for investigating advanced composite thick plates than two-dimensional (2D) theories. The present study examines the specific dimensionality effect of quasi-3D HSDT theories through-thickness stretching on the free vibration behavior of thin-thick rectangular plates. For this purpose, a 3D displacement field defined by only five unknowns is proposed. Besides, it contains a stretching component that contributes to the whole behavior of the plate. The results of the 2D model are compared to the results of the quasi-3D model. In addition, several factors, such as the aspect ratio, geometrical ratio, and material index, illustrate the influence of dimensionality. Young’s modulus and densities should be graded in the direction of thickness. The motion equations are deduced based on Hamilton’s principle. According to the boundary condition type, Navier’s solution method is used for solving the obtained equations. The results show that the inclusion of the stretching component would increase the dynamic response of the thick advanced composite plates. Moreover, the influence of dimensionality is less significant for pure ceramic plates.
Influence of Mechanical and Geometric Characteristics on Thermal Buckling of Functionally Graded Sandwich Plates
(2022-06-30) Abdelhakim Bouhadra
Functionally graded materials (FGM) are a new range of composite materials having a gradual and continuous variation of the volume fractions of each of the constituents (in general, metal and ceramic) in thickness, which accordingly causes changes in the overall thermomechanical properties of the structural elements they constitute. The interest of this work is the use of a high-order plate theory for the study of thermal buckling of FGM plates resting on Winkler-Pasternak type elastic foundation. The present method leads to a system of differential equations, where the number of unknowns is five. The material properties of FGM plate such as Young's modulus and coefficient of thermal expansion are assumed to be variable through the thickness according to the Mori-Tanaka distribution model. The thermal loading is assumed to be uniform, linear and nonlinear through the thickness of the plate. A parametric study is thus developed to see the influence of the geometric and mechanical characteristics, in particular, the geometric ratio (a/b), thickness ratio (a/h) and the material index (k), as well as the impact of the Winkler and Pasternak parameters on the critical buckling load
QUASI-3D ANALYTIC MODEL FOR FREE VIBRATION ANALYSIS OF SIMPLY SUPPORTED FUNCTIONALLY GRADED PLATES (SS-FGP)
(2023-03-09) Abdelhakim Bouhadra
This paper uses a quasi-3D shear deformation theory accounting for integral terms and including the stretching effect to study the free vibration of FG plates with simply supported edges. A new function shape is used to show the variation of tangential stresses through the z-direction of the plate. Poisson’s ratio is supposed to be constant, but Young’s modulus and densities are assumed to be graded in the thickness direction according to the power law function. The present plate theory satisfies the zero tension on the upper and lower surfaces of the FG plate without using shear correction factors. The equations of motion are obtained via Hamilton’s principle and solved using Navier’s solution type. The present natural frequencies correspond with the ones in many publications; the outcomes of geometrical ratio, side to thickness ratio, and the material index on the natural frequencies of SS-FGP are investigated.
Stability analysis of imperfect FG sandwich plates containing metallic foam cores under various boundary conditions
(2024-02-05) Abdelhakim Bouhadra
This research investigates the influence of porosity on the stability behavior of thick functionally graded sandwich plates subjected to mechanical loads, addressing a critical gap in current understanding. It employs a novel quasi-3D high shear deformation theory used here to study the behavior of multi-type sandwich plates. Unlike high-order deformation theories (HSDT), which require correction factors, this model introduces five variables without such adjustments. The current model employs a novel displacement field incorporating indeterminate integral variables, enabling a more accurate representation of complex deformation patterns. The mechanical properties of the FG layers are assumed to vary across their thickness according to a power law distribution (PFGM). The FG layers’ porosity and step functions are characterized in two models, while a third model includes a metal foam core. The concept of virtual work is applied to derive the governing equations for mechanical stability analysis, which are then solved using the Navier solution technique. The results are validated against existing data in the literature, and a detailed discussion explores the impact of side-to-thickness ratio, aspect ratio, material index, loading type, porosity, and various foam shapes on critical buckling behavior
Static buckling analysis of bi-directional functionally graded sandwich (BFGSW) beams with two different boundary conditions
(2022-08-09) Abdelhakim Bouhadra
This paper presents the mechanical buckling of bi-directional functionally graded sandwich beams (BFGSW) with various boundary conditions employing a quasi-3D beam theory, including an integral term in the displacement field, which reduces the number of unknowns and governing equations. The beams are composed of three layers. The core is made from two constituents and varies across the thickness; however, the covering layers of the beams are made of bidirectional functionally graded material (BFGSW) and vary smoothly along the beam length and thickness directions. The power gradation model is considered to estimate the variation of material properties. The used formulation reflects the transverse shear effect and uses only three variables without including the correction factor used in the first shear deformation theory (FSDT) proposed by Timoshenko. The principle of virtual forces is used to obtain stability equations. Moreover, the impacts of the control of the power-law index, layer thickness ratio, length-to-depth ratio, and boundary conditions on buckling response are demonstrated. Our contribution in the present work is applying an analytical solution to investigate the stability behavior of bidirectional FG sandwich beams under various boundary conditions.
Theoretical buckling analysis of inhomogeneous plates under various thermal gradients and boundary conditions
(2023-03-16) Abdelhakim Bouhadra
This study investigates the theoretical thermal buckling analyses of thick porous rectangular functionally graded (FG) plates with different geometrical boundary conditions resting on a Winkler-Pasternak elastic foundation using a new higherorder shear deformation theory (HSDT). This new theory has only four unknowns and involves indeterminate integral variables in which no shear correction factor is required. The variation of material properties across the plate’s thickness is considered continuous and varied following a simple power law as a function of volume fractions of the constituents. The effect of porosity with two different types of distribution is also included. The current formulation considers the Von Karman nonlinearity, and the stability equations are developed using the virtual works principle. The thermal gradients are involved and assumed to change across the FG plate’s thickness according to nonlinear, linear, and uniform distributions. The accuracy of the newly proposed theory has been validated by comparing the present results with the results obtained from the previously published theories. The effects of porosity, boundary conditions, foundation parameters, power index, plate aspect ratio, and side-to-thickness ratio on the critical buckling temperature are studied and discussed in detail.

Browsing by Author "Abdelhakim Bouhadra"

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