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Nombre total de résultats : 1420
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S. Boukhezar, K. BEY, L. Alimi, S. BOUDIAF, M. Boulkra (2018)
Article de conférence

In order to improve the performance of Poly(methyl methacrylate)/glass fibers composite used in the fabrication of the prosthetic socket, we try to introduce powdered pits as reinforcements with Poly(methyl methacrylate) resin (PMMA) to form hybrid composite. The presented work consists, firstly, in optimizing the experimental parameters for the preparation of a PMMA / glass fibers composite loaded with organic particles. Then, Tensile strength (TS) tests were conducted to assess the mechanical properties of the prepared specimensVoir les détails

Mots clés : Prosthetic Socket, Hybrid Polymer Composites, mechanical properties, PMMA, Pits Date Powder

Elaboration Of Laminated Composite Plates By The LRI Process

W. Djerir, R. Halimi, H. Barkat and Ali Badidi Bouda (2018)
Article de conférence

The aim of this work is the elaboration oflaminated composite plates based on the LRI (liquid resininfusion process). This process makes it possible to producelightweight composite plates, with the possibility of theirapplications in the structural parts production of variousdimensions in many industrial sectors such as aeronautics,transport and building. In this process, the use of the adjustabletemperature heating plate replaces the autoclaves required inthe development of composites. In contrast to existing processes,it does not require high pressure during the polymerizationphase. The infusion of the resin is also done automatically by avacuum pump. In addition, because of the absence of a mold onthe upper part, vacuum bag made of nylon or silicone is used.Voir les détails

Mots clés : LCM : Liquid Composite Molding; LRI: Liquid Resin Infusion; laminated composite materials; vacuum pump; glass fiber; carbon fiber.

Puzzle of c-WN phase stabilization

W. RICHI, D. ZANATI (2018)
Article de conférence

In this paper, we present first-principles calculationsthat compare structural and electronic properties of WN inthe NaCl and NbO phases. Our results predict that the NbOstructure of WN is more stable than the NaCl structure withoutdefects, where the enthalpy of formation per formula unit Hf =-0.872eV and 0.616eV for NbO and NaCl structures, respectively.Moreover, the calculated lattice parameters of c-WN are a=4.35A°and a=4.11A° for NaCl and NbO phases, respectively. It is veryclear that the lattice parameter obtained for c-WN in NbO is invery good concordance with that reported experimentally of a =4.14A° . Although the formation energy calculations support thehypothesis of the stability of the NbO phase, the experimental xrayphotoelectron spectroscopy (XPS) electron density of statesfor valence band spectra corresponds to that density of statescalculated for c-WN in NaCl phase. Based on this comparison,more consideration must be taken into account to elucidate thisissue.Voir les détails

Mots clés : Cubic Tungsten nitride ceramics, Firstprinciples calculations, Formation energy

Modal Analysis For Composite Sandwich Plates Of Honeycomb Core

Gaagaia, Guenanou, Ahmed Belaadi, Aouaichia, Bouakba, Fergani (2018)
Article de conférence

.The purpose of this work is to realize a vibratory study on panel’s sandwiches established by the honeycomb core and aluminum skins, used in the conception of the aerospace structures; all the analyses are based on conditions in the embedded free limits (E-L-L-L). The aim is to compare the natural frequencies of the two plates with those obtained from the two simulation models. Two methods are used in modeling, 3D drawing of the sandwich structures and calculating an equivalent structure using the homogenization method based on representative elementary volume (REV) using ANSYS software. The modal resolution of these two configura-tions is performed by the finite element method. The comparison of numerical results shows excellent agreement.Voir les détails

Mots clés : Sandwich plate, homogenization, FRF's, modal analysis, Finite element method.

Description of the solid method of BaTiO3 ceramics elaborations

Guessoum Mounia, Boukazouha Faiza, Sedda Kamel (2018)
Article de conférence

Abstract— There are two major methods of the barium titanate ceramic BaTiO3 elaboration, the solid and the liquid methods (Hydrothermal, sol-gel processing, and Coprecipitation) [1, 2, 3].In this work, we present a theoretical study to describe the solid method of BaTiO3 elaboration, it is the most method used in the industry, because it is very economical, inexpensive and easier to implement.Voir les détails

Mots clés : component formatting; style; styling; insert

Determination of the elastic parameters of thermoplastic composites using the indentation technique

A. Mokhtari, N. Tala-ighil, A. Brick Chaouche, Y.A. MASMOUDI (2018)
Article de conférence

this work deals with the application of the macroindentation technique to the determination of the elastic parameters of composite with polypropylene matrix and reinforced with ductile and brittle fibers. The aim is to obtain a representatives average values taking into account the influence of the holding time and type of the used reinforcement (ductile or brittle reinforcement) on the overall elastic modulus of the studied polymers. To do this, the diameter of the indenter used ischosen relatively large (diameter of 16 mm) and the load equal to 6 kN. The various results obtained made it possible to see the effects of the holding time and the type of reinforcements used on the evolution of the elastic modulus of the reinforced compositeVoir les détails

Mots clés : thermoplastic composites, macro-indentation test, viscoplastic behavior

Synthesis, characterization and structural study of perovskite ceramics for piezoelectric applications

K. Sedda, R. Djafar, K. Boumchedda, F. Boukazouha, M. Guessoum, A. Badidi Bouda (2018)
Article de conférence

In this work we have prepared lead-free ceramics BaTiO3, CaTiO3 and Ba0.85Ca0.15Ti0.9Zr0.1O3 successfully from different raw materials barium carbonate (BaCO3) calcium carbonate (CaCO3) dioxide of titanium (TiO2) and zirconium dioxide (ZrO2) by the conventional solid state reaction technique at different sintering temperatures. These materials are mixed for 6 hours and sintered at temperatures of 1200 °C to 1300 °C for 2 hours. The sintering temperature has been varied to study its effects on microstructure and structural properties. Structural parameters were analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM). Differential thermal analysis coupled with thermogravimetric analysis (ATG-ATD) was performed mainly to follow the process of precursor decomposition and formation of the perovskite phase. The XRD analysis results clearly show the synthesis of the perovskite phase as well as highlighting the formation of the Ba2TiO4 phase in addition to the BaTiO3 phase. The diffractogram obtained shows that the BCTZ symmetry is both Cubic with a space group Pm-3m and orthorhombic with a space group R3m. The calculated phase rates are: 10% and 90% respectively.Voir les détails

Mots clés : Lead free ceramics, synthesis, microstructure, Perovskite

Simulation and Modeling of Uncertainties in the Calibration of a Fluorescence Chemical Spectrometer (FRX)

S. Djemili, A. HAMOUDA, D. BERDJANE, B. Maalem (2018)
Article de conférence

Sensitivity analysis and uncertainty estimation are of major importance for the declaration of conformity of finished products. Models must be sought to analyze the test data. The main objective of this work is to establish reliable models to analyze our experimental data and validate them. So we have studied and used the Monte Carlo and Bootstrap simulation methods, we have been able to realize programs that calculate the uncertainty according to the ISO 8466 standard on X-ray fluorescence spectrometer samples from the URASM CRTI chemical analysis laboratory. Programs and interfaces are made with Matlab (GUI).Voir les détails

Mots clés : Simulation; uncertainties; Monte carlo; Bootstrap; calibration

The influence of scale yielding conditions in the determination of the fracture load using both analytical and numerical approaches for the study of the elasto-static anti-plane problem of a crack in a semi-infinite strip containing a non-homogeneous zone

Article de conférence

The elasto-static anti-plane problem of a crack in a semi-infinite strip containing a non-homogeneous zone was studied using two approaches. The first one consist on an analytical approach based on the solution of a Singular Integral Equation (SIE formulation) using the Dugdale-Barenblatt cohesive model and the second approach is a numerical method based on a finite element analysis using a bilinear cohesive model (FEM-CZM approach). The results were expressed in term of fracture load. The length of the developing cohesive zone ahead of the crack tip was deduced at the crack initiation. This critical length size which was normalized with the crack size is taken as a characteristic length for defining the small/large scale yielding conditions of the particular studied case. For the small cohesive zone sizes (small scale yielding conditions), the computed values of the fracture load show a small difference between analytical and numerical approaches. In the other hand for the case of large cohesive zone sizes, the obtained values of the fracture load show significant discrepancy between the two approaches.Voir les détails

Mots clés : Crack, Singular Integral Equation, FEM, cohesive models, scalCrack, scale yielding conditions

Synthesis and characterization of Nickel oxide (NiO) thin films

Bouhank .A, Serrar.H, Bellal .Y (2018)
Article de conférence

For the synthesis of Nickel oxide as thin films, with the spray pyrolysis technical as a chemical method of deposit, on ordinary glass substrates heated to a fixed temperature of 500 °C. we use Nickel nitrate hexahydrate (99.5 %, Aldrich) as source precursor, dissolved in distilled water. Nickel oxide is a p-type semiconductor, is an important material because of its large direct optical gap between 3.6 and 4.0 eV; and easy to deposit in thin layers by many techniques, such as sol-gel and spray pyrolysis. Diagrams of X-ray diffraction (XRD), to confirm the formation of the phase have characterized the structure of the films deposited by the pyrolysis spray technique. Where they showed that NiO are nanoparticle films and have preferred orientations according to (111) and grain sizes in the range of 15 to 48 nm. The surface morphology, absorption domain, molecular vibrations were characterized by scanning electron microscopy (SEM), UV-Visible Spectroscopy and Raman spectroscopy.Voir les détails

Mots clés : NiO, Raman, UV-Visible Spectroscopy, XDR