Browsing by Author "BETTAYEB Mohammed"

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    Effect of fiber packing on transverse shear modulus G23 of a unidirectional composite material Glass / Epoxy
    (2022) BREK Samir; Meddour Belkacem; BETTAYEB Mohammed
    Composite materials are widely used in the manufacture of mechanical and civil engineering structures. These materials are characterized by heterogeneity and anisotropy, so they present a great challenge of the prediction of the mechanical characteristics of the matrix/fiber mixture and especially in the transverse plane (2-3). The values of the transverse shear modulus G23 are always interesting researchers because of the diversity of results obtained by several approaches (analytical, numerical) and this modulus is used to study the mechanical behavior of composites in 3D. The main objective of this study is the predicting of G23 values within a unidirectional composite material with 44.3% fibers by volume, and to study the effect of the random position of the fibers on the mechanical behavior in shear for ten representative square elementary volumes (RVEs). Each RVE is composed of 16 cells (fiber with matrix or matrix without fiber) with a side of 48 μm. The composite material used in the numerical modeling corresponds to a unidirectional ply (UD) based on epoxy resin and long glass fiber (E) with a circular section. The developed numerical model to determine the transverse shear modulus G23 is carried out using finite element software CASTEM. Ten calculation programs using the GIBIANE language were developed. The obtained results were compared with those obtained by analytical and other available numerical models.
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    Optimization of the mass of laminated composite structures stressed in membrane and bending
    (2022) BETTAYEB Mohammed; BREK Samir; BEZAZI Abderezak
    Nowadays, industrialists are more and more interested in integrating composite parts into their creations, especially in aerospace, naval, and railway. Where these materials present many advantages, in particular, that allow a reduction of the mass of the parts when they are correctly exploited. Laminated composites offer the greatest flexibility, as they allow a variation in the thickness of the stacks throughout the structure made of composite materials often have the characteristic of being modular structures, i.e. constituted by the assembly of several elementary units. Optimization is the process of designing structures that best meet a given set of criteria. The weight optimization of laminated composite structures is of primary interest especially when one is interested in aeronautical applications, and in order to achieve an efficient optimization, it is then necessary to take into account the optimization variables (materials, orientations, thicknesses of the layers as well as the total number of layers n). This introduces complications both in the formulation and in the solution of the associated optimization problems. In this study, we propose to develop an efficient numerical optimization method to solve the optimal design problem of a laminated structure (with glass/epoxy UD plies) solicited in membrane, bending, or membrane-bending coupling using the classical theory of laminates (CTL) and the two software Scilab and Castem for the validation of the obtained results (constraints and homogenization)