Publications Scientifiques

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Author: search.filters.author.Nour, Abdelkader

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    Mechanical properties and low-velocity impact analysis of camel hair and hybrid camel hair/flax fibre-reinforced epoxy
    (Springer, 2024) Bencheikh, Amir; Nour, Abdelkader; Casimir, Jean B.; Aguib, Salah; Gherbi, Mohammed T.; Attia, Nourhane; Djedid, Toufik; Baali, Besma. R.; Aribi, Chouaib
    Composite plates structures are subjected to many damage problems under low-velocity impacts such delamination and matrix cracking, in order to know the importance of hybridisation on improving mechanical properties. This study explores the low-velocity impact behaviour of two composites: one reinforced with camel hair fibre/epoxy (CHF/Epoxy) and the other with a hybrid of camel hair and flax fibres camel hair fibre–flax fibre/epoxy (CHF-Flax/Epoxy). Static tests (tensile, compression, and bending) were conducted to characterise the mechanical properties of the composites. Impact tests were performed using a drop weight impact machine at three energy levels (3, 7, and 20 J). Particularly, the hybrid composite plate (camel hair fibre/epoxy) exhibited superior mechanical properties in static tests, leading to enhanced impact resistance compared to the composite plate (camel hair fibre/epoxy). Additionally, a numerical study was conducted using a 3D finite elements model. The Hashin criteria and the progressive damage model were used to predict intralaminar damage, and surface-based cohesive behaviour with quadratic stress failure criteria was used to predict delamination. The progressive damage model was coded and its implementation is conducted with a user-defined material subroutine (VUMAT) for Abaqus/Explicit. The damage mechanism and energy dissipation were observed at each energy level. Matrix cracking occurred first, followed by delamination. The 3D damage model was able to simulate the damage initiation and damage evolution until failure. The results of the model showed good agreement with experimental results in term of force, displacement and energy dissipation curves.
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    Impact Behavior Analysis of Luffa/Epoxy Composites Under Low-Velocity Loading
    (Springer Nature, 2024) Grabi, Massinissa; Chellil, Ahmed; Lecheb, Samir; Grabi, Hocine; Nour, Abdelkader
    Luffa cylindrical (LC) has an exceptionally multipartite architecture, a hierarchical and light structure, and a low density. Such a structure is potentially suitable to replace conventional porous-type composites for low-energy absorption and material reinforcement applications. This paper presents an experimental study of the impact behavior of four different luffa/epoxy composites, named (A), (B), (C), and (D) subjected to low-velocity impact (LVI) at energies ranging from barely visible impact damage (BVID) to perforation (5,15, and 20J). Acoustic emission (AE), scanning electron microscopy (SEM), and digital image correlation (DIC) were introduced to the indentation test to offer additional information on damage mechanisms and on strain and displacement fields since the LVI test has a short duration and real-time damage monitoring is not always achievable. The results showed that the values of the peak force of laminates (A), (B), and (D) are relatively lower compared to laminates (C). In the case of perforation impact energy (20J), the Coefficients of Restitution (CoR) of composites (A), (B), and (D) are equal to 0, which indicates that the nature of the impact is completely plastic, except for composite (C) had a value of 0.11, and a lower degree of damage at all impact energies. Composites (C) exhibit the highest impact resistance, followed by composites (A), while composites (D) display the highest energy absorption, followed by composites (B). Multivariable statistical analysis of the AE signals identified four classes of damage: matrix cracking, fiber-matrix debonding, delamination, and fiber breakage. The damage modes found by AE are well presented and proven by SEM analysis. The luffa fiber-reinforced composite has better impact properties than other natural fiber-reinforced composites.
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    Mechanical Properties of Alfa, Sisal, and Hybrid Alfa/Sisal Fiber Satin Cloth Reinforced Epoxy
    (Springer Nature, 2024) Baali, Besma R.; Gherbi, Mohammed Tahar; Nour, Abdelkader; Casimir, J.B.; Saci, Rachid; Aguib, Salah; Attia, Nourhane; Aribi, Chouaib
    The mechanical behavior of composites, made of an epoxy resin matrix reinforced by 30 and 40% of a satin cloth from long Alfa, sisal and hybrid Alfa/sisal fibers was studied. The fibers are obtained by extraction with elimination of binders such as pectins and lignin. For each type of fibers, appropriate and optimal chemical and thermal treatments were conducted within NaOH solution, to enhance both the fiber surface quality and the interfacial bonding between fibers and matrix. Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and chemical decomposition of treated and untreated fibers lead to prove the treatment efficiency. The thermogravimetric (TGA) and differential thermogravimetric (DTG) analyses showed better thermal stability. Differential scanning calorimetry (DSC) made it possible to quantify the enthalpy changes which showed an increase in the amount of heat as a function of the increase in weight fraction of natural fibers. The endothermic reaction of the composites studied containing 30 wt% fiber reinforcement was less than that containing 40 wt% fiber reinforcement. The composite materials were produced by vacuum assisted resin transfer molding (VARTM) method due to hydrophilic nature of the fibers. The results of static tests were compared to those of pure epoxy resin. It showed a significant increase for 40 wt% woven A1lfa/epoxy of about 333, 113, and 81% in tension, 3-points bending and compression tests respectively. SEM morphology analysis revealed good interfacial adhesion between the treated fibers and the matrix.
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    An efficient approach for solving differential equations in the frame of a new fractional derivative operator
    (MDPI, 2023) Attia, Nourhane; Akgül, Ali; Seba, Djamila; Nour, Abdelkader; la Sen, Manuel De; Bayram, Mustafa
    Recently, a new fractional derivative operator has been introduced so that it presents the combination of the Riemann–Liouville integral and Caputo derivative. This paper aims to enhance the reproducing kernel Hilbert space method (RKHSM, for short) for solving certain fractional differential equations involving this new derivative. This is the first time that the application of the RKHSM is employed for solving some differential equations with the new operator. We illustrate the convergence analysis of the applicability and reliability of the suggested approaches. The results confirm that the RKHSM finds the true solution. Additionally, these numerical results indicate the effectiveness of the proposed method
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    Dynamic characterization of the magnetomechanical properties of off axis anisotropic magnetorheological elastomer
    (De Gruyter Open, 2022) Bendjeddou, Walid; Aguib, Salah; Chikh, Noureddine; Nour, Abdelkader; Djedid, Toufik; Kobzili, Lallia; Meloussi, Mounir
    The use of magnetorheological elastomers in the mechanical and acoustic fields, by the automotive, aeronautical, and building industries, is currently developing strongly and rapidly. The perfect understanding of the capacity of smart insulation based on the absorption of the vibratory waves by magnetorheological elastomers materials passes by the knowledge of their dynamic mechanical behavior. In this present work, we have characterized the dynamic mechanical properties of the magnetorheological elastomer off axes anisotropy by the inclination, of different angles (15°, 30°, and 45°), of the pseudo-fibers of the iron particles formed by the application of a magnetic field at different intensities using an optimal loading rate of 30%. The rubber specimens were prepared by mixing micron-sized iron particles dispersed in room temperature vulcanized (RTV) silicone rubber by solution mixing. The experimental results obtained show a clear dependence of the effect of inclusion of ferromagnetic chains on the magnetomechanical properties. It is observed that the mechanical properties are better when applying a magnetic field of 0.6 T with an angle of inclination of 45°. The improvements added in this work could be useful in several industrial applications, such as automotive, aeronautic through adaptive control of damping and vibration level
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    A novel method for fractal-fractional differential equations
    (Elsevier, 2022) Attia, Nourhane; Akgül, Ali; Seba, Djamila; Nour, Abdelkader; Asad, Jihad
    We consider the reproducing kernel Hilbert space method to construct numerical solutions for some basic fractional ordinary differential equations (FODEs) under fractal fractional derivative with the generalized Mittag–Leffler (M-L) kernel. Deriving the analytic and numerical solutions of this new class of differential equations are modern trends. To apply this method, we use reproducing kernel theory and two important Hilbert spaces. We provide three problems to illustrate our main results including the profiles of different representative approximate solutions. The computational results are compared with the exact solutions. The results obtained clearly show the effect of the fractal fractional derivative with the M-L kernel in the obtained outcomes. Meanwhile, the compatibility between the approximate and exact solutions confirms the applicability and superior performance of the method
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    Numerical solutions to the time-fractional swift–hohenberg equation using reproducing kernel hilbert space method
    (Springer, 2021) Attia, Nourhane; Akgül, Ali; Seba, Djamila; Nour, Abdelkader
    In this work, a numerical approach based on the reproducing kernel theory is presented for solving the fractional Swift–Hohenberg equation (FS-HE) under the Caputo time-fractional derivative. Such equation is an effective model to describe a variety of phenomena in physics. The analytic and approximate solutions of FS-HE in the absence and presence of dispersive terms have been described by applying the reproducing kernel Hilbert space method (RKHSM). The benefit of the proposed method is its ability to get the approximate solution of the FS-HE easily and quickly. The current approach utilizes reproducing kernel theory, some valuable Hilbert spaces, and a normal basis. The theoretical applicability of the RKHSM is demonstrated by providing the convergence analysis. By testing some examples, we demonstrated the potentiality, validity, and effectiveness of the RKHSM. The computational results are compared with other available ones. These results indicate the superiority and accuracy of the proposed method in solving complex problems arising in widespread fields of technology and science
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    Numerical solution of the fractional relaxation-oscillation equation by using reproducing kernel hilbert space method
    (Springer, 2021) Attia, Nourhane; Akgül, Ali; Seba, Djamila; Nour, Abdelkader
    In this article, the reproducing kernel Hilbert space is proposed and analyzed for the relaxation-oscillation equation of fractional order (FROE). The relaxation oscillation is a type of oscillator based on the way that the physical system’s returns to its equilibrium after being disturbed. We make use of the Caputo fractional derivative. The approximate solution can be obtained by taking n-terms of the analytical solution that is in term of series formula. The numerical experiments are used to prove the convergence of the approximate solution to the analytical solution. The results obtained by the given method demonstrate that it is convenient and efficient for FROE
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    Measurements and identification of smart magnetomechanical elastomer composite materials properties in shear mode
    (Institute of Physics Publishing, 2019) Nedjar, Ali; Aguib, Salah; Djedid, Toufik; Nour, Abdelkader; Meloussi, Mounir
    Magnetorheological elastomer composite materials (MRE) are a new class of intelligent active materials composed of ferromagnetic particles, of micrometric size, dispersed in a silicone elastomer matrix, which exhibit variable stiffness and damping properties which are modifiable under the application of an external magnetic field. Currently, these devices are primarily used in automotive and building applications, but they can easily be adapted to meet the requirements of aerospace applications. The development process and experimental characterization needed to evaluate the active control performance of this material have been made. This is done by characterizing the mechanical properties as a function of the magnetic field, as a function of the excitation frequency and as a function of the different percentage of ferromagnetic particles loading. An example of application of this material in aeronautics is also presented
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    Modeling a Composite Reinforced with Short Alfa Fibers to Determine its Fatigue and Structural Homogenization
    (Springer, 2018) Nour, Abdelkader; Mechakra, Hamza; Benkoussas, B.; Tawfiq, I.; Settet, A. T.; Renane, R.
    The fatigue and homogenization of polypropylene reinforced with untreated and chemically treated short Alfa fibers were investigated using a modified Mori–Tanaka model. The polypropylene with chemically treated fibers showed a higher resistance than that with untreated ones. Cylindrical fibers with elliptical cross sections were used in experiments. Their mechanical characteristics were determined by the inverse method.