Browsing by Author "Belgacem Mamen"

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    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) Belgacem Mamen
    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
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    Coupled effect of variable Winkler–Pasternak foundations on bending behavior of FG plates exposed to several types of loading
    (2022-09-15) Belgacem Mamen
    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.
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    Microstructural observations of shear zones at cohesive soil-steel interfaces under large shear displacements
    (2021-04-27) Belgacem Mamen
    Failure mechanism which can affect geotechnical infrastructures (shallow foundations, retaining walls, and piles) constitutes one of the most encountered problems during the design process. In this respect, the shear behavior of interfaces between grained soils and solid building materials, as well as those between cohesive soils should be investigated. Therefore, a range of ring shear tests with different cohesive soils and stainless-steel interfaces have been carried out through the Bromhead apparatus that allows simulating large displacements along a failure surface. The effects of steel rings roughness and soil type on the residual friction coefficient and the shear zone features (structure, thickness, and texture orientation angle) have been investigated using the Scanning Electron Microscopy. The obtained results indicate that the residual friction coefficient and the structural characteristics of the shear zone vary according to the surface roughness and the soil type. Scanning electron microscopy reveals that the particles inside the shear zone tend to be re-oriented. Also, the shear failure mechanism can be identified along with the interface, within the soil, or simultaneously at the interface and within the soil specimen.
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    Stability analysis of imperfect FG sandwich plates containing metallic foam cores under various boundary conditions
    (2024-02-25) Belgacem Mamen
    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.
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    Theoretical buckling analysis of inhomogeneous plates under various thermal gradients and boundary conditions
    (2023-03-16) Belgacem Mamen
    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.