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Characterizations of joints HDPE welded by FSW

LATEF M, ZAHLOUL H, BADIDI BOUDA A, MEBTOUCHE A, ABBASE A  (2018)
Article de conférence

The aim of this work is the characterization of high density polyethylene (HDPE) joints welded by the Friction Stir Welding (FSW) technique. The characterization is done by destructive testing (mechanical tensile tests) for welded joints.To do this work, a series of experimental tests were made by taking in account of several parameters: - the geometry of the welding tool (pin), the axial force Fz applied to the tool along its axis of rotation, to compensate for the pressure formed in the weld zone, the speed of rotation of the tool, the speed of advance of the tool,in this work, we only take in account of the last two parameters.The results obtained were satisfactory and show the influence of these parameters on the quality of the joint. Voir les détails

Mots clés : FSW, HDPE, polymers, welding

PRISE EN COMPTE DE L’ASPECT NON LINÉAIRE DANS L’ANALYSE MODALE DES STRUCTURES MÉCANIQUES

LATEF Mohamed, A?AD Abedelkarime  (2016)
Article de conférence

La connaissance des caractéristiques modales est primordiale dans l’étude du comportement dynamique des structures. L’application de l’analyse modale a été souvent réservée au domaine linéaire. Cependant, la plupart des structures mécaniques, rencontrées dans la pratique, présentent un comportement plus ou moins non linéaire. L’aspect non linéaire est d’origines diverses, dépend de plusieurs facteurs et peut se manifester globalement (géométrie, propriétés mécaniques,…) ou localement (conditions aux limites, joints, …).Dans ce travail, nous avons applique l’analyse modale a des systèmes vibratoires discrets (masse-ressort) non linéaires d’aspect géométrique.Plusieurs méthodes ont été utilisées pour déterminer les paramètres modaux, a savoir :- Balance harmonique (analytique).- Variété de l’invariant de Shaw-Pierre (numérique).- Range Kutta d’ordre 4.Des programmes ont été établis sous matlab pour exploiter ces méthodes. Les résultats obtenus nous ont permis de préciser :- la limite entre les systèmes linéaires et non linéaires.- l’effet des conditions initiales et le paramètre non linéaire.- domaine d’application des méthodes permettant l’étude des systèmes non linéaires. Voir les détails

Mots clés : analyse modal, Non linéarité, vibration, Paramètres modaux (Fréquences et Modes propres)

Experimental study of the thermo-mechanical behaviour of alumina-silicaterefractory materials elaborated from Algerian kaolinitic clays

A.GRID, N. TOUATI, S. LADJAMA, A. Mebrek, H.Rezzag, S.Bouchoucha  (2018)
Article de conférence

This work aims to study the thermomechanical behavior of an algerian kaolinitic clay. We started with the characterization of the raw material (DD1) of Djebel Debbagh -Guelma, in order to obtain a deep information about the microstructure of the material before and after a heat treatment, notably its crystallographic nature and the grains size and shape. The chemical composition and physical properties are reported. The mineralogical and chemical characteristics, based on X-ray diffraction (XRD) and scanning electron microscopy (SEM), were also carried out. The general behavior of the material with increasing temperature was analyzed through the various microstructure investigations and thermal analysis. Voir les détails

Mots clés : Thermo-mechanical properties, aolinitic clays, elaborate

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

Corrosion of AISI4130 in différents électrolytiques solution

ALLOU Djilali, MIROUD Djamel, CHENITI Bilal  (2018)
Article de conférence

This article discusses the electrochemical behavior of AISI 4130 alloy steel in various electrolyte solutions H2SO4, HCl and NaCl. Corrosion tests were carried out on a potentiostat / galvanostatat room temperature in the various electrolytes, under an Ag / AgCl reference electrode with .Electrochemical Impedance Spectroscopy (EIS) measurement. The results obtained through the tafel curves show that the corrosion process can be divided in two parts highlighting the aggressivity of Cl- ions. The impedance which is characterized by a large semicircle in the Nyquist graph increases under H2SO4.Equivalent circuits have been determined to represent the corrosion processes at differente ectrolytes. Voir les détails

Mots clés : AISI 4130, electrolytes H2SO4, HCl and NaCl

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 composite Voir 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