Génie mécanique

Nombre total de résultats : 213
Pertinence Titre A-Z Plus récents Plus anciens
10 25 50
Année de publication

Simulation du comportement et de l’endommagement mécanique d’un matériau composite sandwich

Mémoire de Master

This work is dedicated to the study of an advanced approach based on the modeling of the behavior and damage of the glass/epoxy sandwich composite in polyether imide core under tensile and shear loading. In particular, we are interested in the study of the damage coupled to the rupture of this sandwich composite. These sandwich composites are used in fields such as aeronautics and automotive. Their uses call for the development of reliable constituent models to predict their responses under complex loading conditions. This model considers all damage in the plane: damage caused by cracking of the epoxy matrix as well as damage due to the rupture of the glass fabrics in the longitudinal and transverse directions. For this study a model has been designed as two layers plus one PEI layer [0°/90°]. For this purpose various experimental results were established in order to develop a model for damage analysis, whose composite response is governed by a coupling between damage and failure. In order to develop this study, we used finite element software (ABAQUS/Standard), by which we proceeded to obtain simulation results presented in this work and thus, correctly predict the static response obtained by the experimental measurements. Voir les détails

Mots clés : modeling, thermo set matrix sandwich composite, mechanical behavior, tensile test, Stress, Strain, deformation, damage, breakage.

Caractérisations microstructurale et mécanique de soudures hétérogènes (2205/X52) réalisées par friction rotative : Effet de temps de friction

Mémoire de Master

This work consists of joining two different materials grades, the dual phase SAF 2205 duplex stainless steel and an API X52 high strength low alloy (HSLA) steel using the solid state welding process (Rotary Friction). The aim of this experimental work is to study the friction time effect on microstructural evolution of the obtained heterogeneous joints and identify the different zones affected by this process. A mechanical characterization is also planned in this study, in order to highlight the consequences of friction time on some mechanical properties through hardness, microhardness and tensile tests. Voir les détails

Mots clés : SAF 2205, duplex stainless steel, API X52, tensile tests

Etude de la soudabilité de l'alliage d'aluminium 7075 soudé par le procédé de soudage par point par friction malaxage FSSW

Mémoire de Master

The welding of metal structures and constructions in various industrial sectors is tending towards the intensive use of modernized welding processes such as FSSW. In order to reduce the weight of metallic devices and structures, the replacement of riveting by welding is considered in the current research. In the present work, the interest will be focused on the study of this process. Sheets in AA7075-T6 are welded using different speeds of rotation and depth of penetration, we have used several simple but effective analytical methods suitable for this type of research, such as mechanical tests, such as tensile tests and hardness tests, to determine the best properties for a good weld that can maintain the mechanical properties of the base materials. We also conducted a microscopic study to detect the different zones in welding position, and we reached zones, which are ZM ZAT ZATM These zones result from the heat generated by the friction that occurs between the welding tool and the aluminum plates. We show that increasing the speed of rotation and the depth of penetration of pawn increases the resistance of the weld joint. So we obtain a tensile force equal to 2.03 kN at a speed of 1800 rpm and a penetration value of 3.4 Voir les détails

Mots clés : ZM ZAT ZATM, welding of metal structures, FSSW, AA7075-T6

Caractérisation physico-chimique et électrochimique d’un soudage par friction rotative

Mémoire de Master

The objective of This dissertation of master is to perform rotary friction welding . the first is to carry out a homogeneous welding by varying the speed of rotation and the second is to carry a heterogeneous welding AL2017/ Steel 304L . We follow a physico-chemical and electrochemical characterization on its two types of welding . Voir les détails

Mots clés : Rotary friction welding, AL2017/ Steel 304L, types of welding

Caractérisation mécanique jonctions d’assemblables :acier inoxydable 304L /alliages de types ZY-4

ch. Charikhi, M.Y. Yendjah  (2022)
Mémoire de Master

In order to avoid or minimize the appearance of the harmful phases in the zone of diffusion of the works employed aiming at controlling the flow of diffusion of the chemical elements through the interface, although studies are undertaken, the nature of the compounds, the formation kinetics of certain phases and the number of zones formed at the interface in the temperatures of their practices, between 950-1100°C, remain controversial. The data related to the compromises between the operating parameters of the welding thermal cycle, in particular the temperature and the holding time of the isothermal bearing during a direct bond Zy4/steel are not very developed in the literature. The recent results obtained on the shape of the interface and the nature of the phases formed which will serve as a basis for the interpretation of the results which will be obtained and presented in the last chapter. The ZPR consists of three layers regardless of the holding temperature The CI ~ 4 to 6 μm thick type - is located on the steel side. The thickness CII is practically independent of temperature, formed of a mixture of ε+Zr2 phases between 950 and 1020°C and of ε+-Zr phases for T=1050°C. Its thickness as well as its microstructure strongly depend on the holding temperature. The thickness of the ZPR evolves continuously up to 1020°C and increases drastically when T=1050°C . Results obtained from the evolution of the thickness of the reaction product zone as a function of residence time e=f, used to define the experimental parameters are used to select the thickness of the ZPR. During these steps the liquid fraction is gradually increasing and the thickness of CIII becomes drastically enlarged after 45 minutes of isothermal holding. Voir les détails

Mots clés : diffusion of the chemical elements, harmful phases

Modélisation du comportement mécanique des constituants du palmier dattier

GUETTAF TEMAM Tahar (2017)
Thèse de doctorat

Dans les régions arides et semi arides, nous retrouvons les palmiers dattiers en masseet cette richesse joue un role important au dévellopement de ces dernières, spécialement dansl’activité économique et sociale. Sachant que la datte est le fruit des palmiers mais reste à savoirqu’il dispose aussi d’un bois de tronc et de palmes assez important utilisés dans les fabricationstraditionnelles relatives à ces régions ou entant qu’engrais fertilisant les terres utiles, cespratiques sont limitées raison du manque de données scientifiques et techniques dans cedomaine. Dans otre recherche une large base de données techniques aussi physique, technique tmicroscopique définissant l’aspect morphologique des fibres et du bois des variétés Deglet Nour,Mech Degla et El Ghers pris encharge par cette étude de recherche. Des caractérisations on étéréalisées telle que la microscopie optique, le taux d’absorption et le taux d’humidité ont révélésbeaucoup de déductions aussi des tests mécaniques telle que les tests de traction ont été réalisés. Voir les détails

Mots clés : Palmier, palmier dattier, bois, microstructure de bois, caractérisation mécanique, modélisation

Effect of ball burnishing process on mechanical propertiesand impact behavior of S355JR steel

Mounira Bourebia, Hamid Hamadache, Laouar Lakhdar, Zoheir MENTOURI, Djemili Kamila, Hazem Tarek, Taleb Ahlem  (2021)

Often, surface mechanical treatment (SMT) or heat (quenching, tempering) is used to improve the surface condition andmechanical characteristics such as impact resistance and tensile strength. Hence the objective of this experimental work, whereball burnishing (BB) as well as quenching and tempering were applied on S355 JR steel specimens, is to evaluate the surfacehardness Hv, the rupture strength Rm, the energy absorbed W during the impact test, and the work-hardened thickness e after theburnishing operation. Factorial designs were used for the test organization and mathematical models were established for theprediction of Hv, Rm, W, and “e” in function on treatment parameters considered: number of tool passes (i) and the pressure force(Py). The results show that the surface hardness increases by 30.46%. The high levels of Py and i were allowed to improve Rm by30.8% as well as an increase in tenacity of only 3.6%. Increasing the force to 20kgf promotes mixed rupture under the effect ofimpact to shock. The quenching and tempering improve the Rupture strength Rm by 183% and 119%, respectively, while theeffect of burnishing was limited to a rate of increase of this property of 28% compared to machining. Voir les détails

Mots clés : Tensile resistance . Burnishing . Heat treatment . Superficial hardness . Absorbed energy . Penetration depth . Ruptures facies

Experimental Study Of The Effect Of Shot Peening Parameters On The Surface Texture - Influence On The Adhesion Of A Paint Coating

M.Bourebia, S.Meddah, Z.Mentouri, A.Oulabbas, S.Achouri, L.Laouar  (2022)

The investigation presented in this paper focuses on the effect of surface texture on the adhesion of a paint coating as well as the influence of shot peening regime parameters on the surface isotropy indicator "Str" and on the fractal dimension "Df". The tests have been organized according to full factorial designs 23, where three parameters have been examined, at their two levels (min, max), namely the pressure (P), the angle of attack (θ) and the time (t). 3D roughness measurements have been carried out to characterize the different surfaces after a shot peening operation. A mathematical model linking the input parameters (P, θ, t) and the output parameter "Str", in the study area has been established, and the fractal dimension (Df) has been used for the surface characterization. Paint deposit has been applied to surfaces and adhesion tests have been carried out. The results show the significant effect of the impact angle on "Str", and the interaction between the different parameters in the studied area. Furthermore, the greatest bond strength has been obtained with the sample 3 (F = 4.25 N / mm2), whose the isotropy indicator "Str" is equal to 0.6438 and the fractal dimension Df = is about 1.768. Voir les détails

Mots clés : surface texture, fractal dimension, shot peening, Adhesion

A probabilistic approach to estimate the remaining life and reliability of corroded pipelines

Zelmati Djamel, BOULEDROUA Omar, GHELLOUDJ Oualid, AMIRAT Oualid, Milos B. Djukic  (2022)

Considering corrosion rate during the remaining life assessment of aging pipelines is fundamental to calculate the interval between two consecutive inspections. A total of 798 internal and external corrosion defects have been detected, using the Magnetic Flux Leakage intelligent inspection tool, over 48 km of a pipeline length located in the west region of Algeria. The statistical analysis has shown that there is a strong correlation between the corrosion defect length and the corrosion defect circumferential width, with a significant correlation coefficient equal to 82.87%. A probabilistic methodology is presented for the assessment of the remaining life of a corroded pipeline transporting gas, and a finite element method (FEM) was used to assess the pipeline failure pressure. The numerical FEM modeling results were compared with the commonly used codes-models for calculating limit pressure to establish a more realistic and accurate engineering model. The reliability analysis of an API 5L X60 steel made Algerian natural gas pipeline, in service for thirty years, and exposed to active corrosion attack, is presented. The sensitivity analysis of the basic random variables within the nonlinear limit state function was carried out to bring out the relative contribution of each variable affecting the remaining life of corroded pipelines. The reliability analysis is carried out by using Breitung’s formula, based on the second-order reliability method (SORM). The reliability assessment of the corroded pipeline is based on the usage of the notched failure assessment diagram (NFAD), different codes for the calculation of the failure pressure, and the numerical results using the finite element analyses (FEA) software ANSYS. Voir les détails

Mots clés : Corrosion defects, pipelines, Remaining life, Probability of failure, Reliability, Probabilistic approach

Reliability Estimation of Cracked API 5L X70 Pipeline Steel


The aim of this paper is to estimate the reliability of cracked pipeline steel grade API5L X70 used for hydrocarbon transportation, by coupling a developed mechanical model, basedin one hand on the simulation of cracked specimen, and an experimental result of tensile and Charpy test, and in the other hand, based on a reliability model by using a first-order reliability method (FORM). These pipes are produced by the Algerian company of manufacture of welded pipes (ALFAPIPE Annaba). The experimental task such as resilience and tensile test were carried out on specimens taken from a pipe in the longitudinal and the transversal directions. The resilience tests are carried out at different temperatures in order to estimate the fracture toughness of the material, basing on a global correlation. Besides, tensile tests are performed to bring out the mechanical characteristics of the material. After, the stress intensity factor is assessed using the analytical model of IRWIN. In the reliability analysis, the limit state function is attributed to the moment when the stress intensity factor estimated by Irwin mechanical model, is equal tothe fracture toughness of the steel pipe. The basic random variables within the limit state function are assumed to follow a normal distribution in order to simplify the assessment. Then, the evaluation of the reliability index and the parameters sensitivities of the cracked pipelines steel are assessed. Voir les détails

Mots clés : Reliability, Cracked API 5L X70, Pipeline Steel