Publications Internationales

Permanent URI for this collectionhttps://dspace.univ-boumerdes.dz/handle/123456789/13

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Subject: search.filters.subject.Natural frequencies

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Now showing 1 - 5 of 5
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    Elastic wave propagation and dynamic response of multidirectional FG beams under varying thermal conditions
    (Taylor and Francis, 2025) Bourouis, Mohammed El Amin; Dahmane, Mouloud; Nebab, Mokhtar; Benadouda, Mourad; Ait Atmane, Hassen; Bennai, Riadh
    The present research proposes an in-depth analysis of wave propagation in simply supported functional gradient (FG) porous beams subjected to complex thermal environments. The novelty of this study lies in the consideration of a thermal distribution applied unidirectionally (1D), bidirectionally (2D), and tridirectionally (3D) through the thickness, thickness and width, and then the thickness, width and length of the beam, respectively. Thermal loads dependent on and independent of mechanical properties are introduced to simulate realistic service conditions, enabling better anticipation of the dynamic response of FGM structures in thermally unstable environments. The power law function is intended to change the structure’s mechanical and physical characteristics as its thickness, width, and length increases. By applying Hamilton’s principle, the governing equations for elastic wave propagation under thermal loading are rigorously established. The problem is formulated as an eigenvalue system in order to derive the analytical dispersion relation in the unidirectional, bidirectional, and tridirectionally cases. The effects of temperature distribution types, wave propagation numbers, and volume fraction distributions on the wavpropagation dynamic of an imperfect functionally graded beam are subjected to extensive considerations
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    Dynamic characteristics analysis of functionally graded cracked beams resting on viscoelastic medium using a new quasi-3D HSDT
    (Taylor & Francis, 2024) Kehli, Ahmed; Nebab, Mokhtar; Bennai, Riadh; Ait Atmane, Hassen; Dahmane, Mouloud
    In this study, a new four-unknown quasi-3D shear deformation theory is proposed for studying the vibration responses of functionally graded (FG) beams containing open-edge cracks resting on three-parameter viscoelastic foundations (VEFs). The number of unknowns and governing equations in the current theory has been reduced, making it easier to use. Even less than conventional theories, this theory includes indeterminate integral variables and contains only four unknowns where no shear correction factor is used. The study is conducted with an eye toward a three-parameter foundation that takes into account the effects of the elastic medium’s damping coefficient, the Pasternak coefficient, and the Winkler coefficient. The material characteristics of the FG beams are considered to vary in the thickness direction via a power law distribution as a function of the volume fractions of the constituents. The system of differential equations governing the free vibration behavior of FG beams is derived by Hamilton’s principle. To satisfy the foundation conditions, the Navier method is used to obtain the analytical solutions of the dynamic response of cracked FG beams resting on viscoelastic foundations. Comparison of the results of the current theory with other results and with data available in the literature demonstrates its accuracy. A detailed parametric study is presented to show the impact of material properties, slenderness ratio, foundation type and foundation damping coefficient, crack depth, and location on the natural frequencies of cracked FG beams resting on VEFs.
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    Crack identification in plates-type structures using natural frequencies coupled with success-history based adaptive differential evolution algorithm.
    (EBESCO, 2023) Brihmat, Chahira; Amoura, Nasreddine; Lecheb, Samir; Kebir, Hocine; Ait Chikh, Mohamed Abdessamad; Tablit, Bassima
    In this study, a new method for identifying and characterizing straight cracks in plate-like structures is presented. The method combines the finite element method (FEM) using the software Abaqus and the success history-based adaptive differential evolution algorithm (SHADE). The objective of the method is to minimize the mean relative error between the measured experimental frequencies of a plate with an unknown crack identity and the numerical frequencies obtained using the Shade-FEM approach. The crack identity is defined by its length, orientation, and centre coordinates. To validate the effectiveness of the proposed approach, two strategies are applied. In the first strategy, the inverse problem is solved using the natural frequencies of a plate with a known crack identity obtained through modal simulation in Abaqus. In the second strategy, the experimental frequencies of a cracked plate are used. The results of the study demonstrate that the proposed approach achieves promising results with just a population size of 25 and 150 iterations. The outcomes show high accuracy, as indicated by a relative error of the objective function below 0.8%. Overall, the study demonstrates the effectiveness of using the Shade-FEM approach for identifying and characterizing straight cracks in plate-like structures, offering potential applications in various engineering and structural integrity fields.
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    Damage detection and localization in composite beam structures based on vibration analysis
    (2015) Khatir, Samir; Belaidi, Idir; Serra, Roger; Magd, Abdel Wahab; Khatir, Tawfiq
    This paper presents an approach of inverse dam-age detection and localization based on model reduction. The problem is formulated as an inverse problem where an optimization algorithm is used to minimize the cost func-tion expressed as the normalized difference between a fre-quency vector of the tested structure and its numerical model. A finite element model of bi-dimensional monolith-ic composite beam reinforced by a graphite-epoxy is used to define a numerical model of the tested structure in which different scenarios of damage are considered by stiffness reduction. Then, calculations are made on a re-duced model built by the technique of proper orthogonal decomposition coupled by radial basis functions. The accu-racy of the method is verified through different damage configurations. The results show that the developed algo-rithm is a feasible methodology of predicting damage in short computing time and with high accuracy. The effect of noise on the accuracy of the results is investigated in some cases for the structure under consideration
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    Design and optimization of a CPW-fed tri-band patch antenna using genetic algorithms
    (Applied Computational Electromagnetics Society (ACES), 2015) Fertas, K.; Kimouche, H.; Challal, Mouloud; Aksas, Hammouche; Aksas, R.; Azrar, Arab