administrative publication and meeting mirutes

Permanent URI for this collection

http://localhost:4000/handle/123456789/43

Browse

Browsing administrative publication and meeting mirutes by Issue Date

Filter results by year or month
Now showing 1 - 20 of 36
  • No Thumbnail Available
    Item
    The influence of fiber arrangement on the mechanical properties of short fiber reinforced thermoplastic matrix composite
    (Revue des Composites et des Matériaux Avancés, 2017) Khelifa MANSOURI
    Short fibers are becoming increasingly popular reinforcing elements in products made by extrusion or injection molding. Short-fiber reinforcement allows the polymer to be processed employing the same methods as those used for unreinforced polymers. In short fiber composites, loads are not directly applied on the fibers but are applied to the matrix and transferred to the fibers through the fiber ends. Thermoplastics reinforced with short fibers are increasingly used in many industrial applications due to their attractive mechanical properties, rapid processing and relatively low manufacturing cost. However, the concentration and the orientation of the fibers vary from one point to the other. In this work, multi fiber composite model was analyzed under tensile load. The purpose of this work is to analyze the influence of fiber arrangement on the Von Mises stress of glass fiber reinforced thermoplastic nylon66 matrix composite using finite element analysis (FEA).
  • No Thumbnail Available
    Item
    New modified selective platinum electrode based on poly (ethylene glycol) for Iron (III) detection in real water
    (MECHERI NACIRA, 2017-11-04) Nacira Mecheri, Messaoud Benounis, Houcine Barhoumi,
    Purpose – This work aims to determine iron (III) in real water by using a new amperometric sensor on the basis of polyethylene glycol (PEG) to test and characterize a new modified selective platinum electrode. Design/methodology/approach – In this review, the authors focus on testing and characterizing several polymeric membranes by using cyclic voltammetry and square-wave voltammetry (SWV) methods to differentiate the nature of plasticizers (2-Nitrophenyl octyl ether [NPOE], Di-n-octyl phthalate, Bis (2-ethylhexyl) sebacate, PEG. The authors have evaluated the possibility of using crown ether and three zeolite ionophore (faujasite [FAU], Chabazite and ZSM-5) matrixes as novel materials for the selective determination of iron (III) using SWV for the best membranes. Findings – The results demonstrated that the modified platinum electrode presents linear dependence of amperometric signal with a wide linear range of 10 9 to 10 4 mol.L 1 for iron determination, revealing a detection limit of 10 10 mol.L 1 and amperometric sensibility of 58.58 mA/mol. L 1 . The slope of the membrane plasticized with PEG calibration curve is six times higher than that of the other membranes. It was noticed that when the crown ether and the three zeolite ionophores were used, as a new detective material for iron with the membrane plasticized with PEG, the expected results were highly proven. The modified platinum electrode showed high selectivity to iron (III) when the heavy metal ions such as Ni (II), Al (III), Zn (III), Cd (II), Gd (II) and Cu (II) were present. Originality/value – The utility of the method and the efficiency of the best membrane sensor have been accurately tested by the determination of iron in real water samples of Hassi Messaoud, south of Algeria.
  • No Thumbnail Available
    Item
    Iron (III)-Selective Sensor Based on Modified Glassy Carbon Electrode
    (2018) MECHERI NACIRA
    The aim of this work is intended to make a comparison between the effects of the presence of potassium ferricyanide (K3[Fe(CN)6]) / potassium ferrocyanide K4[Fe(CN)6]) and the absence of any redox couple for iron (III) determination in aqueous solution using modified Glassy Carbon Electrode. Benzo-18-crown-6 is employed as ionophores for preparing PVC-based membrane sensors selective to iron (III), plasticized with Di-n-octyl phthalate, Tetrabutylammonium tetraphenylborate was used as additive. The measurements performed and characterized by square wave voltammetry methods. Agents were optimized for iron (III) stripping analysis and optimal condition was frequency of 20 Hz, step potential of 6 mV, amplitude of 40 mV, the modified glassy carbon electrode immersed in standard solutions of Fe(III) at PH 2.0 .The measurements are performed in 0.1M NaNO3 and 0.1 M HCl (pH 7). The square wave voltammograms showed a sharp peak around positive potentials + 0.260 V that was used for construction of the calibration curve in a work range from 10-10 until 10-6 mol L-1 of iron, exhibiting a linear correlation coefficient of 0.99, a detection limit of 10-10 mol L-1 and sensibility of 9. /mol L-1, especially, those obtained by the presence of redox couple better than the absence of external redox.
  • No Thumbnail Available
    Item
    Modelling Mechanical Properties of AISI 439-430Ti Ferritic Stainless Steel Sheet
    (2019-05-14) Chahaoui
    The comprehension of the anisotropy impacts on mechanical properties of the rolled steel sheets was investigated using a nonquadratic anisotropic yield function. In this study, experimental and modelling determination regarding the behaviour of an industrial rolled sheet for a ferritic stainless low-carbon steel were carried out. The parameters of the associated yield equation, derived from the three orthotropic yield functions proposed by Hill48, Yld96 and Yld2000-2d, were determined. Predictions and the evolution of normalized yield stress and normalized Lankford parameters (plastic strain ratio) obtained by the presented investigative are considered. The forecasts given by the YLD2000-2d criterion are consistent with that of the experience. In order to describe the path of strain behavior, the isotropic hardening function is described using the following four empirical standard formulae based on: Hollomon, Ludwick, Swift and Voce law. More accurately, the anisotropy coefficients of three yield functions are represented as a function of the longitudinal equivalent plastic strain.
  • No Thumbnail Available
    Item
    Constitutive Modelling of an Industrial Rolled Sheet for a DIN 1623 St14 (DC04) Steel
    (2019-09-17) Chahaoui
    The comprehension of the anisotropy impacts on mechanical properties of the rolled steel sheets was investigated using a non-quadratic anisotropic yield function. In this study, experimental and modelling determination of behavior of an industrial rolled sheets for a DIN 1623 St14 steel were carried out. The yield stresses and Lankford r-values in uniaxial were experimentally determined but the balanced biaxial tension stress states and rb were assumed. The parameters of the associated yield equation, derived from the three orthotropic yield functions proposed by Hill48 and Yld2000-2d, were determined. Predictions and the evolution of normalized yield stress and normalized Lankford parameters (plastic strain ratio) obtained by the presented investigative are considered. In order to describe the path of equivalent plastic behavior, the isotropic hardening function is described using the following various empirical standard formulae based on: Hollomon, Ludwick, Swift and Voce model.
  • No Thumbnail Available
    Item
  • No Thumbnail Available
    Item
    Mechanical Behavior of Particle Reinforced Thermoplastic Matrix Composites Using Finite Element Modeling
    (JOURNAL OF NANO- AND ELECTRONIC PHYSICS, 2020-10-25) Khelifa MANSOURI
    Particles are becoming increasingly popular reinforcing elements in products made by injection molding. Particles reinforcement allows the thermoplastic to be processed employing the same methods as those used for unreinforced thermoplastic. Ultrafine particles, whose diameters are comparable to the crystalline regions in the polymer, have a prominent reinforcing effect on the elastic properties of the polymer. Small particles adhere strongly to the polymer, which leads to a strong reinforcing effect. In particle reinforced thermoplastic matrix composites, loads are not directly applied to the particles but are applied to the matrix, and some of the applied loads are transferred to the particles. The process of transfer of load between particles and matrix depends on the strength of the interface. In this work, multiparticle composite model was analyzed under tensile load. The purpose of this work is to analyze the influence of particle diameter (the diameters of 19.61, 26.15, 39.22 and 78.45 m were used) on the Von Mises stress of glass particle reinforced thermoplastic nylon 66 matrix composite using finite element analysis (FEA). The second objective is to analyze the effect of particle packing (square, hexagonal and random arrangement) on nanocomposite behavior.
  • No Thumbnail Available
    Item
  • No Thumbnail Available
    Item
  • No Thumbnail Available
    Item
    Experimental Study and Modelling of the Ferritic Steel Anisotropic Behavior under Associated and Non-Associated Flow Rule
    (2021-01-05) Chahaoui
    In the present study, two different yield criteria were investigated to model and compare the yield thresholds functions for the plastic behavior of rolled sheets. These two different yield criteria as described via Hill48 yield quadratic and F. Barlat Yld2000-2d non-quadratic criterion. For this purpose, an experimental device of simple tensile test and the studied material are described. The experimental results in terms of Yield stress and Anisotropic coefficient are estimated from the Associated Flow Rule (AFR) and Non-Associated Flow Rule (NAFR). However, it is found that the criterion of Yld2000-2d is the most appropriate model in comparison with the experimental results.
  • No Thumbnail Available
    Item
    Application of Associated and Non-Associated Flow Metal Plasticity for F.S.S Sheet
    (2021-01-11) Chahaoui
    In the last decade, several phenomenological yield criteria for anisotropic material has been proposed to improve the modeling predictions about sheet metal-forming processes. In regard to this engineering application, two proprieties of models have been used. If the yield function and the plastic potential are not same (not equal), the normality rule is non associative flow rule (NAFR), otherwise, when the stresses yield has been completely coupled to the anisotropic strain rate ratio (plastic potential), is called the associated flow rule (AFR). The non-associated flow rule is largely adopted to predict a plastic behavior for metal forming, accurately about à strong mechanical anisotropy presents in sheet metal forming processes. However, various studies described the limits of the AFR concept in dealing with highly anisotropic materials. In this study, the quadratic Hill1948 yield criteria is considered to predict mechanical behavior under AFR and NAFR approach. Experiment and modeling predictions behaviour of normalized anisotropic coefficient r (θ) and σ (θ) evolved with θ in sheet plane. and the equibiaxial yield stress σb was assumed σb=1 but the rb-values was computed from Yld96 [15]
  • No Thumbnail Available
    Item
  • No Thumbnail Available
    Item
  • No Thumbnail Available
    Item
    Influence of the carburization time on the structural and mechanical properties of XC20 steel
    (2021-08-21) Chahaoui
    This study focuses on the effect of carburization time on the structural and mechanical properties of low carbon XC20 mild steel (C. Wt.%<0.25). The XC20 steel was carburized with activated carbon with a carbon potential Cp1=1.1%, at 910 °Cat different carburization times of 2, 4 and 6 h. The results obtained show that XC20 steel (non-carburized) has a ferrite-pearlitic structure with a hardness and a Young’s modulus of the order of (150 HV, 26KN/mm2). After carburization, the structure of the carburized layer is transformed in martensite (Fe γ) in which cementite (Fe3C) is imbricated. The depth of the carburized layer and the amount of carbon on the surface gradually increase with increasing carburization time. In addition, the carburized XC20 steel becomes hard and brittle where the hardness and Young’s modulus have been increased for a high holding time until reaching maximum values (845 HV, 48KNmm−2) after 6 h of carburization . However, the toughness of XC20 steel has been reduced from 163 to 40 J cm−2.
  • No Thumbnail Available
    Item
    An Associated and Nonassociated Flow Rule Comparison for AISI 439-430TI Forming: Modeling and Experimental Analysis
    (2021-09-21) Chahaoui
    The plastic anisotropy behavior of ferritic stainless steel (FSS) sheets was analyzed and modeled under associated and nonassociated flow rule approaches. Three orthotropic flow functions, known as quadratic Hill48 and nonquadratic (Yld2000-2d and BBC2005), were developed and employed under an associated and nonassociated flow rule hypothesis. For the NAFR based on the initial anisotropy, the mechanical behavior was described by the nonexponential model functions of Yld2000-2d and BBC2005 to predict the directional dependence of mechanical parameters. It provided a considerable advantage in terms of flexibility and good agreement with the experiment. According to the results, the polynomial fit functions of the transverse versus longitudinal true plastic strain curve were used to describe the designated properties corresponding to a selected level of strain. To describe the evolution of anisotropic hardening and potential plastic hardening, seven different loading conditions were considered. The proposed evolutionary non-AFR Yld2000-2d and BBC2005 criteria showed good accuracy in predicting the evolution of hardening yield and Lankford coefficients depending on the plastic deformation.
  • No Thumbnail Available
    Item
  • No Thumbnail Available
    Item
  • No Thumbnail Available
    Item
    Effect of Reinforcing Particle Shape on the Behavior of Composites Materials
    (JOURNAL OF NANO- AND ELECTRONIC PHYSICS, 2021-12-20) Khelifa MANSOURI
    In this paper, the effect of particle shape on the mechanic behavior of glass particle reinforced composites is evaluated. Small particles adhere strongly to the polymer, which leads to a strong reinforcing effect. When the total contact surface increases, more loads are transferred to the reinforcing particles. In our previous studies, it has been shown that addition of circular particles with decreasing diameter does not affect the composite. The objective of this research is to investigate the mechanical behavior of thermoplastic matrix composite nylon 66, reinforced with glass particles, under unidirectional tensile loading using finite element analysis. Numerical results are presented for a variety of particle shapes, including circular, triangular, square, rhombic, pentagonal and hexagonal. The results show that Von Mises stresses consistently increased as the shape of the reinforcing particles changed from triangular to square, rhombic, pentagonal, hexagonal and circular in this order.
  • No Thumbnail Available
    Item
  • No Thumbnail Available
    Item