Optimisation et Analyse des Assemblages Soudés par Friction Malaxage (Friction Stir Welding) et Ses Applications Dans l’Industrie des Polymères
Projets de recherche
Description:
Dans ce projet, nous voulons montrer la faisabilité du
soudage par la technique FSW pour assembler des matériaux
polymères (soudage des tôles, fabrication des pipes etc.). Cette
étude sera développée dans pour une éventuelle optimisation et
vérification de l’influence de plusieurs paramètres liés à l’outil
et aux paramètres de coupe sur la qualité des joints soudés. Il
serait intéressant de vérifier l’apport d’une énergie extérieure
en termes de flux thermique sur l’opération du malaxage et
donc sur la tenue mécanique des joints.
La présente étude est une contribution à une analyse
paramétrique en vue d’optimiser les paramètres de soudage
extrinsèques et intrinsèques (vitesse de rotation, vitesse
d’avance de l’outil, géométrie de l’outil, mode de fixation…)
afin d’évaluer leurs influences sur le comportement global du
joint soudé. Cette étude nous permet d’établir des lois de
comportement des matériaux polymères soudés par FSW. Cette
phase est nécessaire pour la mise en place d’outils de
simulation numérique pour réduire le nombre d'essais
expérimentaux nécessaire à l'optimisation du procédé. L’enjeu
étant de procéder un couplage entre le procédé et les propriétés
mécaniques des pièces soudées
Code de projet: A11N01UN290120190001
Agrées le : en 2019-01-01
Publications
Estimation of the energy of crack propagation in different zones of a welded joint by the local technique
La revue : Internatianal journal of Fracture
Domaine : Mots Clés : Microhardness · Plastic zone · Local energy · Cracking · E48 Steel
Auteur : B. Bouchouicha, M. Zemri, A. Zaim, B. Ould Chikh
Issn : 2369-0739 Eissn : 2369-0747 vol : 192, Num : , pp : 107–116
Date de publication : 2017-03-31
Résume : The fatigue damage of a material generally
goes through of an incident or a heterogeneity producing
a local stress concentration. The growth of crack is
related to the existence of a plastic zone at the crack
tip and accompanied by an energy dissipation. The
objective of this study is to analyze the evolution of
the energy at the crack tip during the propagation of
a crack in a welded joint. In order to determine the
energy nearest the end of the crack in the plastic zone,
we used microhardnessmeasurements. The estimate of
the total strain in each measurement point was determined
by a polynomial relation between Hv and εt /2.
After the determination of the average strain, the total
energy in each zone was deducted. The higher value
of this energy is in the Weld Metal, it is more lower
in the Base Metal and even lower in the Heat Affected
Zone.
The effect of the plastic instability on the behavior of an amorphous polymer
La revue : Mathematical Modelling of Engineering Problems
Domaine : Mots Clés : Amorphous Polymer, Damage, Mechanical Behavior, Modeling
Auteur : Ali Boudjelal Moulay., Bouiadjera Bachir Belabbes., Ould Chikh El Bahri, Elmeguenni Mohamed,
Issn : 2369-0739 Eissn : 2369-0747 vol : 4, Num : 1, pp : 53-58
Date de publication : 0000-00-00
Résume : In manufacturing operations, numerous parts and components are formed into different shapes by applying external forces to the workpiece, typically by means of various tools and dies. Common examples of such operations are forging, extruding, drawing and rolling. Forming operations may be carried out at room temperature or at elevated temperatures, and at a low or a high rate of deformation. These operations are also used in forming and shaping non-metallic materials such as plastics and ceramics. However, the processes of working of polymers in a solid state are affected by phenomena of plastic instabilities. These phenomena are interpreters on the basis of intrinsic law of behavior of the material which express the influence of the deformation and the rate of deformation on the plastic yield stress. This law directly reflects the structural modifications undergone by material under the conditions of the test. In addition, she gives the necessary information to the modeling of instabilities using techniques of calculation such as the finite element method.
Mise en œuvre de l’essai d’indentation pour modéliser le comportement mécanique des aciers
La revue : Revue des matériaux et énergies renouvelables
Domaine : sciences des matériaux
Mots Clés : small punch test ; plan d’expériences ; optimisation ; dimensionnement ; contraintes
Auteur : S. Habibi, L. Aminallah, A. Megueni, B. OuldChikh, A. S. Bouchikhi
Issn : Eissn : vol : 1 , Num : 1, pp : 8-15
Date de publication : 0000-00-00
Résume : La technique small punch test (SPT) d’un échantillon en miniature est mise en oeuvre pour estimer la charge ultime de l'acier ductile CrMoV. Les courbes caractéristiques par SPT (F-d) pour différentes combinaisons des variables d’essai (épaisseur du spécimen, diamètre du punch et matrice inférieure) ont été examinées. L’objet de cette étude est la mise en oeuvre d'une méthodologie d’optimisation susceptible d’évaluer et de concevoir le dimensionnement du dispositif d’indentation qui répond à la fois aux exigences des modèles implémentés et au modèle proposé par le plan d’expériences. On a adopté une démarche fondée sur l’approche comparative entre les plans d’expériences et les deux méthodes (code de pratique européenne et méthode de Norris et Parker). Le modèle mathématique élaboré par plan d’expériences est implémenté sous Matlab, permet à partir d’un espace de recherche considéré (données de références), une optimisation des paramètres du dispositif, en minimisant l’écart entre les modèles étudiés, sous contraintes pratiques liées au système d’indentation ‘’Pièce-Outil-Machine’’. Les résultats obtenus à une erreur de 0.5*e-3 permettent de déterminer le domaine admissible.
Characterization of thermally affected steels by nanoindentation
La revue : Recueil de mécanique
Domaine : sciences des matériaux
Mots Clés : Heat treatments; Characterization; Nanoindentation; Modulus of elasticity; Hardness
Auteur : Samir Habibi, Noureddine Mahmoudi, Benaoumeur Aour, Laid aminallah, Ould Chikh el bahri
Issn : Eissn : vol : 2, Num : 002, pp : 168 – 174
Date de publication : 2018-01-20
Résume : The thermal affectation is the basis of metallurgical modifications of the base metal
which can induce fragilities, decreases in mechanical strength, lack of ductility ... These
modifications depend on the material examined, the process used, the mode of operation
followed ... This research is devoted to the experimental study, whose objective is the
study of low-carbon steels who sustained of the various heat treatments. Then, the
instrumented nanoindentation test is developed to analyze the characteristic loading and
unloading curves of the examined specimens. In this case, we focus on the effect of heat
treatments on the metallographic examination and the mechanical properties of the
studied steels. At the same time, we study the coherence of the results obtained between
the heat treatment and the nanoindentation process in the determination of elasticity
modulus and hardness.
Caractérisation d’un cordon de soudure Par FSW: Cas des matériaux polymères
La revue : Nature & Technology,
Domaine : sciences des matériaux
Mots Clés : Polymères, essais de traction, FSW, FEM, couplage, procédé-propriété
Auteur : Hachellaf Kaddour, Meddah Hadj Miloud, Ould Chikh El Bahri et Lounis Abdellah
Issn : Eissn : vol : , Num : 18, pp : 83-86
Date de publication : 2018-01-25
Résume : Le but de notre travail expérimental est de proposer un modèle d’outil qui pourrait être utilisé comme un outil prédictif pour obtenir
une bonne soudure des polymères comme le PEHD par la technique de soudage par friction malaxage FSW ou un soudage linéaire des
plaques plates minces. Une série des essais expérimentaux concernant ce type de soudage (FSW) ont été réalisés avec différents type
d'outils en fonction des paramètres optimaux de soudage tel que la vitesse d'avance, la vitesse de rotation, la forme géométrique d’outil, …
etc. Des résultats satisfaisants ont été obtenus montrant l’influence de ces paramètres sur la qualité du joint.
Thermo-Mechanical Characterization of a Thermoplastic Copolyetherester (TPC): Experimental Investigation
La revue : Fibers and Polymers
Domaine : sciences des matériaux
Mots Clés : Thermoplastic elastomers, Rate-dependence, Stress-strain behavior, Volumetric strain
Auteur : Abdel-Nour Zaim, , El Bahri Ould Chikh, Benattou Bouchouicha
Issn : 1229-9197 Eissn : 1875-0052 vol : 19, Num : 4, pp : 734-741
Date de publication : 2018-02-02
Résume :
In this article, the thermo-mechanical characterization of poly(butylene terephthalate)/poly(tetramethylene oxide)
(PBT/PTMO) is studied by thermal analysis, dynamic mechanical analysis, and uniaxial tensile tests. The results of
poly(ether esters) show that the melting temperature is equal to Tm=193 oC, which is 31 oC, lower than that of the melting
temperature of poly(butylene terephthalate) (PBT). Its glass transition temperature, Tg is equal to -61 oC, determined by
DMA. The melting and cooling temperatures (Tm, Tc) after aging at T0+48 h and T0+week are virtually unchanged. Moreover,
the results of the tensile tests show that the effect of the low deformation rate reduces the friction resulting from the sliding
mechanisms between the amorphous and crystalline parts.
The Stress Triaxiality Effect under Large Plastic Deformation of a Polybutylene Terephthalate (PBT)
La revue : International Journal of Engineering Research in Africa,
Domaine : sciences des matériaux
Mots Clés : Triaxiality, Plastic instability, polyester; Damage
Auteur : Abdel-Nour Zaim, Benattou Bouchouicha, Meddah Hadj Miloud, EL Bahri Ould Chikh
Issn : 1663-4144 Eissn : vol : 34, Num : , pp : 13-28
Date de publication : 2018-01-19
Résume :
In this work, we focus on a new generation of polymer named Polybutylene terephthalate
(PBT). In order to analyse and determine true behaviour of this polymer, a special experimental
method was used. Hence, the true stress/strain responses are investigated under a large plastic
deformation in different stress triaxiality frameworks with a particular attention on the volumetric
strain evolution, with their decomposition to an elastic volumetric strain, plastic volumetric strain
and the pure shear. Moreover, the effect of stress triaxiality on the plastic instability and the fracture
strain is also examined. With the plastic instability analysis, it was found that plastic strain
hardening increases gradually with the triaxiality. Finally, in order to evaluate the damage of this
polymer, a theoretical damage formula is proposed.
Thermo-Mechanical Characterization of a Thermoplastic Copolyetherester (TPC): Experimental Investigation
La revue : Fibers and Polymers
Domaine : sciences des matériaux
Mots Clés : Thermoplastic elastomers, Rate-dependence, Stress-strain behavior, Volumetric strain
Auteur : Abdel-Nour Zaim, , El Bahri Ould Chikh, Benattou Bouchouicha
Issn : 1229-9197 Eissn : 1875-0052 vol : 19, Num : 4, pp : 734-741
Date de publication : 2018-02-02
Résume :
In this article, the thermo-mechanical characterization of poly(butylene terephthalate)/poly(tetramethylene oxide)
(PBT/PTMO) is studied by thermal analysis, dynamic mechanical analysis, and uniaxial tensile tests. The results of
poly(ether esters) show that the melting temperature is equal to Tm=193 oC, which is 31 oC, lower than that of the melting
temperature of poly(butylene terephthalate) (PBT). Its glass transition temperature, Tg is equal to -61 oC, determined by
DMA. The melting and cooling temperatures (Tm, Tc) after aging at T0+48 h and T0+week are virtually unchanged. Moreover,
the results of the tensile tests show that the effect of the lo
Numerical Evaluation of Biomechanical Stresses in Dental Bridges Supported by Dental Implants
La revue : Journal of Biomimetics, Biomaterials and Biomedical Engineering
Domaine : sciences des matériaux
Mots Clés : dental bridge, FE analysis study, supporting implants, bone, masticatory load, stress analysis
Auteur : Amel BOUKHLIF, Ali MERDJI, Noureddine DELLA, El-Bahri OULD CHIKH, Osama MUKDADI and Rajshree HILLSTROM
Issn : 2296-9845 Eissn : vol : 37, Num : , pp : 43-54
Date de publication : 2018-06-01
Résume :
The number of supporting dental implants is an important criterion for the surgical
outcome of dental bridge fixation, which has considerable impact on biomechanical load transfer
characteristics. Excessive stress at the bone–implant interface by masticatory loading may result in
implant failure. The aim of this study was to evaluate the impact of the number of implants
supporting the dental bridge on stress in neighboring tissues around the implants. Results of the
study will provide useful information on appropriate surgical techniques for dental bridge fixation.
In this study, osseointegrated smooth cylindrical dental implants of same diameter and length were
numerically analyzed, using three-dimensional bone–implant models. The effect of the number of
supporting implants on biomechanical stability of dental bridge was examined, using two, three and
four supporting implants. All materials were assumed to be linearly elastic and isotropic.
Masticatory load was applied in coron-apical direction on the external part of dental bridge. Finite
Element (FE) analyses were run to solve for von Mises stress. Maximum von Mises stresses were
located in the cervical line of cortical bone around dental implants. Peak von Mises stress values
decreased with an increase in the number of implants that support the dental bridge. Results of this
study demonstrate the importance of using the correct number of supporting implants to for dental
bridge fixation.
Parametric Study of the Mechanical Behavior of FSSW Welded Polymer Plates Using a New Form of Welding Tool
La revue : Defect and Diffusion Forum,
Domaine : sciences des matériaux
Mots Clés : Polymer PEHD; friction-stir spot welding FSSW; assemblage; welding parameters; tools geometries.
Auteur : Abdallah, OULD CHIKH El Bahri, MEDDAH Hadj Miloud, GUERAICHE Larbi, HACHELLAF Kaddour
Issn : 10120386 Eissn : vol : 389, Num : , pp : 205-215
Date de publication : 2018-11-15
Résume : This research paper aims at studying the friction stir spot welding (FSSW) some of
thermoplastic polymer materials (HDPE and HDPE-PMMA) using a specifal geometry tool without
a pin. The effect of the tool geometry on the welds static resistance was studied via several tool
shape, a flat shape below the tool, a shape with concavity angles ranging from 0° to 16°, a flange
shape of the sharp-edged tool, a chamfered flange shape and a rounded shape. This work is done to
increase the surface area of the weld and further to maximize the static strength of the friction stir
spot welding. Experimental tests have been carried out under various operational parameters such
as the tool rotation speed, tool plunge depth and dwell time. This later has been carried out to
highlight the effect of the tool’s geometry and the operational parameters of the welding on the
surface in virtue on static resistance of the friction stir spot welding of thermoplastic polymers.
Tests of lap-shear at speed of 5m/s have showed that the tool geometry plays a very important part.
This study shows that a FSSW welding tool with 4° concavity angle tool and a rounded flange
shape gives the best welding quality for the polymers studied.
Experimental and Numerical Analysis of Volume Change Incited by Porosity in Polyvinyl chloride
La revue : Polymer Science, Series A,
Domaine : sciences des matériaux
Mots Clés : Polyvinyl chloride, stress triaxiality, damage, tensile test
Auteur : B. Moulai Ali, El Bahri Ould Chikh, B. Bachir Bouiadjra
Issn : Eissn : vol : 61, Num : 3, pp : 1–11
Date de publication : 2018-12-06
Résume : The polymers are known to be delicate to hydrostatic pressure. The impact of stress triaxiality proportion
on damage and cavitation has been shown in numerous investigations. This article proposes trial
examinations to control both the stress triaxiality proportion and the void distribution by microscopic observations
of surfaces from tensile tests. For that, the Gurson−Tvergaard−Needleman model was adjusted with
the assistance of a finite element code, by utilizing multi-scale trial information. At that point correlation
between both numerical and analytical models and experimental data was performed.
In addition, a better understanding of the time development of critical parameters, for example, the porosity
(volume change) and the stress triaxiality proportion (hydrostatic pressure), was featured.
Numerical simulation of a steel weld joint and fracture mechanics study of a Compact Tension Specimen for zones of weld joint, Frattura ed Integrità Strutturale
La revue : Frattura ed Integrità Strutturale
Domaine : sciences des matériaux
Mots Clés : Welding; Residual Stress; Energy Release Rate; Stress Intensity Factor.
Auteur : Ahmed Bensari, El Bahri Ould Chikh, Benattou Bouchouicha, Malika Tirenifi
Issn : 19718993 Eissn : vol : 47 , Num : , pp : 17-29
Date de publication : 2019-01-01
Résume : To evaluate the integrity of a structure is to prove its ability to
perform its mechanical functions for all modes of loading, normal or
accidental, and throughout its life. In the context of the nuclear safety, for the
most important structures such as the tank or the primary circuit, the
presence of a degradation in these structures grouping several aspects, such as
cracks created during welding. We seek then, to show the mechanical
resistance for this defect mode. It also seeks to fit the mechanical resistance
of a structure in the presence of a crack when the defects have been detected
during an inspection. In this context, the fracture mechanics provides the
necessary tools to analyze cracked components. Its purpose is to establish a
fracture criterion to foreordain the loading margins in normal or accidental
operating conditions. Each type of rupture must be the subject of a specific
characterization
Mechanical behavior analysis of a Friction Stir Welding (FSW) for welded joint applied to polymer materials
La revue : Frattura ed Integrità Strutturale
Domaine : science des matériaux
Mots Clés : Polymers; Tensile tests; FSW; Vickers hardness test
Auteur : Hachellaf Kaddour, El Bahri Ould Chikh, Meddah Hadj Miloud, Lounis Abdellah
Issn : 19718993 Eissn : vol : 47 , Num : , pp : 459-467
Date de publication : 2019-01-01
Résume : Welding is a technique of fusion joining the material involving
a process of inter-molecular diffusion adhesion. Polymer welding is an
assembly method among several known assembly techniques such as gluing.
This welding process applies to thermoplastics; they have the rheological or
softening characteristics during melting. This process is fast and controlled in
order to obtain a solid and durable mechanical connection on the series parts.
This study focuses on the weldability of high density polyethylene (HDPE)
using the friction stir welding technique. A parametric choice was made to
optimize the operating parameters namely the shape of the welding tool, the
speed of rotation and the speed of advance of the tool. Monotonic tensile
tests were used to compare the mechanical characteristics between a HDPE
test specimen and a specimen taken from an FSW weldment.
It emerges from this study that the FSW welding introduces a weakening of
the joints characterized by a clear decrease of the deformation at break.
