Liste des communications
Simulation of the propagation of cracking by finite element code calculation of a supermartensitic stainless steel pipe
The biggest concern of industrial manufacturers is the sustainability of their equipment and facilities. In the oil sector, for example, cylindrical pipe for the energy transportation to suffer corrosion damage or corrosion stress cracking is a complex problem since it requires to follow the geometry of the crack over time. Many numerical methods are applied to the propagation of fatigue cracks that require conditions to correct limitations in loading term to get results close to reality.The method of Finite Elements is a way to simulate crack propagation. However, it presents two major difficulties, the first is the use of a very fine mesh around the crack tip and the second difficulty is the explicit representation of the crack that the problem of cracking path during the simulation of propagation. Indeed, let the mesh is constructed with a priori knowledge of the route or it is changed every time the crack advance.In this context, we studied law cracking of internal pressure pipe of super martensitic stainless steel 13% Cr and 5% Ni 2% Mo by a simulation using a finite element code "ANSYS " with a calculation of the stress intensity factor and prediction of the lifetime. Voir les détails
Mots clés : simulation, Finite Elements, Crack, Pipe, Super Martensitic Stainless Steel.
A Longitudinal P191 Single Ceramic Piezoelectric Transformer : Comparison between 3D Simulations and Experimental Results
In present study, three longitudinal piezoelectric transformers with size of 18.5×3.5×2 mm3, 26×3×1.5 mm3 and 24×3×2 mm3 are fabricated and tested with a soft PZT ( P191) piezoelectric ceramic. The input and the output part vibrate in longitudinal extensional mode. Three configurations of the input and the output voltage are proposed. The electrical measurements results are successfully compared to a three dimensional (3D) Finite Element Analysis using COMSOL Multiphysics software. Voir les détails
Mots clés : Piezoelectric transformer, 3D simulation, longitudinal vibration, Experimental characterisation
The Bayesian formulation for radiographic image segmentation of welding defect using Mumford and Shah model
In this paper, we propose to use the method ofpiecewise constant level set with the Mumford-Shah model. For imagesegmentation, the Mumford-Shah model needs to find regions andconstant values of the regions, for it we use a variational approachbased on the extraction regional information (mean and variance) forthe process segmentation in an adaptive manner, . Finally, we validate the proposed models by numerical results for radiographic image segmentation Voir les détails
Mots clés : Level set, Mumford shah model, image segmentation
Etude des proprietés structurales , élastiques et électronique de CuS et CuTe par la méthode FP-LMTO
The aim of this work is to study the structural ,electronic and elastic properties of CuS. for this, we use the full-potential linear muffin-tin orbital (FP-LMTO) method in the framework of density-functional theory (DFT). The exchange and correlation energy is described in the generalized gradient approximation (GGA ) using Perdew-Wang parameterization. We have investigated the effect of composition on structural properties such as lattice constants, bulk modulus and band gap. We report the results concerning the variation of thegaps and crossover of the direct, indirect band gap and bowing .Finally, a reasonable agreement is found from the comparison of our results with other theoretical calculations. Voir les détails
Mots clés : CuS, FP-LMTO, electronic properties, elastic proprieties
Elaboration and characterization of a piezoelectric ceramic resonator
In this work. We Synthesized PbTiO3 from PbO and TiO2 oxides from Solid state reaction and we studied the development and manufacture of solid piezoelctrique resonator of PT .We played on parameter as sintering time. We used XRD and SEM for morphological characterization and Analyzer for impedance piezoelectric characterization. Voir les détails
Mots clés : PT, ferroelectric, resonator, impedance, XRD, SEM
Morphology and Mechanical properties of α-grain boundary in Ti-6Al-4V TIG welds.
In this Work, the effect of the TIG Welding process on the Morphology and mechanical behavior of α grain boundary (α-GB) phase appearing in TA6V welds are investigated. Different morphologies are observed depending on the pulsed frequency parameter, namely, the Zig-Zag morphology, the saw-teeth morphology and the normal continuous layer. The micro-hardness of each morphology has been measured and discussed. Voir les détails
Mots clés : TA6V, TIG Welds, α-Grain Boundary, Microhardness
INFLUENCE OF ALLOYING ELEMENTS OF WELD METAL ON MECHANICAL BEHAVIOR OF HSLA-X70 WELDS
In the pipeline industry, the alloying elements are continually evolving as a function of weldability and reliability of steels. For this reason, metallurgists discover and develop every day new base materials like HSLA steels and efficient electrodes. We propose in this work to study the influence of chromium and molybdenum in C-Mn filler metal, hoping to demonstrate their microsturctural evolution and mechanical behavior on welds of high strength steels HSLA-X70. The mechanical properties included hardness, impact and tensile strength was investigated. The results show that, optimal properties of welds correspond to the existence of both molybdenum and chromium in weld metal with proportions varying between 1% and 2.5%. Voir les détails
Mots clés : alloying element, Weld metal, HSLA-X70, TIG welding, mechanical behavior
Protection d’un acier au carbone contre la corrosion acide par un inhibiteur vert
En termes de protection, les inhibiteurs constituent un moyen pratique et économique pour lutter contre la corrosion. Cependant, la mise au point d’inhibiteurs de corrosion non toxiques et biodégradables devient un enjeu primordial. Les extraits de plantes sont devenus importantes comme source d’inhibition écologiquement acceptable, facilement disponible et utilisable pour une vaste gamme de prévention de la corrosion. L'objectif de ce travail consiste à étudier l'action inhibitrice d’une substance verte et naturelle à base de plante, sur le comportement à la corrosion de l’acier au carbone X 70 largement utilisé dans la construction des pipelines, dans HCl 1M, en utilisant différentes techniques électrochimiques. Les résultats obtenus montrent que l’inhibiteur est doté d’un pouvoir inhibiteur appréciable, et le caractère dominant dans notre cas traduit une cinétique de transfert de charge. Voir les détails
Mots clés : acier, corrosion, plante, techniques électrochimiques, efficacité inhibitrice.
SIMULATION DE L’EFFICACITÉ OPTIQUE ET GEOMÉTRIQUE D’UN CONCENTRATEUR SOLAIRE CYLINDRO-PARABOLIQUE
L'utilisation des énergies solaires n'est pas liée uniquement à ses avantages économiques mais surtout à la protection de l'environnement ou il faut trouver des solutions aux problèmes de pollution (énergie propre). Dans la nature, il ya beaucoup de sources d'énergies renouvelables, l'énergie solaire est la plus importante. Le présent travail propose une étude numérique des performances optiques et géométriques d’un concentrateur cylindro-parabolique à eau, nous avans simulé la distribution du flux solaire autour du tube absorbeur à l’aide d’un logiciel SOLRACE en utilisant la méthode de Monté Carlo. La détermination des différents facteurs notament le modificateur de l’angle d’incidence, le facteur d’ombre et les perte d’éxtrimités permet d’avoir les performances optiques du concentrateur. Voir les détails
Mots clés : Concentrateur cylindro-parabolique, Facteur optiques et géométriques, Simulation.
Dual- Polarized CPW- Fed Conformal Antenna for Ultra-Wideband Applications
In this paper, we introduce a new compact dual-polarized conformal slot antenna fed by two orthogonal CPW semi-discs. To achieve a high isolation between the two ports, a strip is inserted diagonally in the ground plane. The simulations are done using the CST Microwave Studio software. The simulated results show that the proposed antenna provides an impedance bandwidth enough to cover the Ultra wideband spectrum, and exhibits a good isolation across the operating band. These features make the proposed concept very attractive for conformal ultra-wideband (UWB) antenna applications which used polarization- diversity technique. Voir les détails
Mots clés : polarization- diversity technique, ultra-wideband (UWB) antenna