Génie mécanique

Nombre total de résultats : 174
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Bearing Fault Diagnosis of Induction Machine Based Empirical ModeDecomposition Energy and Entropy

Issam Attoui, Brahim OUDJANI, Nadir FERGANI, Nadir BOUTASSETA (2019)
Article de conférence

In this paper, according to the non-stationary characteristics of rotatingmachinery vibration signals, a method to the detection and classification of rollingelementbearing faults of induction machine using Empirical Mode Decomposition (EMD)Energy and Entropy is proposed. Firstly, the vibration signals are decomposed into afinite number of stationary intrinsic mode functions (IMFs), then the EMD energy andentropy are calculated. The analysis results from EMD energy and entropy of differentvibration signals show that these parameters will change in different frequency bandswhen bearing fault occurs. Therefore, to identify roller bearing fault class, the bestfeatures extracted from a number of IMFs that contained the most important faultinformation are selected using a wrapper algorithm that use the Adaptive Neuro-FuzzyInference System ANFIS classifier to evaluate subsets of features. The final features couldserve as input vectors of trained ANFIS. The analysis results from roller bearing signalswith inner-race , out-race and ball faults show that the proposed diagnosis approachbased on ANFIS by using EMD to extract the energy and entropy values of differentstationary intrinsic mode functions as features can identify roller bearing fault patternsaccurately and effectively.Voir les détails

Mots clés : EMD, Entropy, vibration signals, bearing Fault diagnosis

Optimization of operating parameters of an ingot mold during continuous casting - case of slab a content high carbon

Mounira Bourebia, Sihem ACHOURI, Soumaya MEDDAH, Amel GHARBI, Oualid GHELLOUDJ (2019)
Article de conférence

Currently, the axes research majority aims to improve continually the quality of continuously cast products. Moreover, to guarantee this quality it is necessary to master operating parameters of casting machine, in particular, the primary cooling phase that takes place at level of ingot mold. The latter animated by an oscillatory movement, generally induces marks and defects on slab surface. Indeed, during descent, the solidified crust is in compression, thus creating a negative sliding, this sliding time will help reduce the sticking risk, to close the rips of solid skin   and to reduce the depth of oscillation marks. In addition, this time depends on casting speed and oscillation parameters of ingot mold (amplitude and frequency). The aim of this work is to optimize the operating parameters of ingot mold in this case the casting speed "v" and oscillations (amplitude "a", frequency "f") at  means of Box-Behnken’s experimental design thus makes it possible to predict the healing rate "τ" which represents the ratio of sliding time and  total cycle time. Mathematical model have been obtained and the results show that for the case of carbon steel slab, strong sheet with a thickness of 250mm, it is recommended to use low speeds (v = 0.6m.mm-1) and large frequencies (n = 200cpm) associated with average amplitudes (a = 10mm) to achieve a value of τmax = 0.470 ± 0.048.Voir les détails

Mots clés : Healing rate, optimization, experimental design, continuous casting, and primary cooling

Improvement the surface hardness of XC38 steel by heat treatment - Approach by factorial plans

3. M.Bourebia, A.gharbi, S. Achouri, S. Meddah, A. Talab, K.BOUHAMLA (2018)
Article de conférence

The surface hardness plays an important role in the service life of a mechanicals parts subjected to friction and wear. It can be improved by mechanical treatments or heat treatments. The latter occupy an important place in steel metallurgy, they aim to improve the performance of mechanicals properties of materials such as resilience and hardness and consequently they contribute in a visible way to the good resistance to fatigue and wear treated pieces. This work aims to predict the surface hardness Hv as a function of heat treatment parameters in this case the treatment temperature and holding time. therefore thermals treatments have been envisaged following the methodology of factorial plans 22 where two parameters have been considered, the temperature "T" and the holding time "t" where each parameter at two levels (min, max). These treatments were applied on forged XC38 steel samples, the obtained results have resulted in a mathematical model evaluating the surface hardness "Hv" as a function of treatment temperature and holding time. The experimental results indicate for this steel that holding time minimum and temperature minimum (t = 2h, T = 850 ° c) have an apparent significant effect where "Hv" achieved the value of 750 (Hvi = 179).Voir les détails

Mots clés : heat treatment, superficial hardness, factorial designs, Mathematical model

Effet des paramètres du régime sur la pente quadratique Sdq

M. BOUREBIA, H. Bounazour, L. Laouar (2017)
Article de conférence

La caractérisation des surfaces en 3D permet des interprétations faciles et intuitives grâce à un jeu de paramètres adéquats, souvent la qualité de surface est évaluée avec le paramètre Ra, actuellement d’autres paramètres sont pris en considération pour apprécier les états de surface fonctionnelles. La dimension fractale Df et la pente quadratique de surface Sdq qui permettent de définir respectivement les irrégularités de surface et de caractériser les différents stades d’endommagement du matériau. Pour estimer ces paramètres, des surfaces en alliage d’aluminium ont été traitées par brunissage en adoptant la méthode des plans d’expériences. les paramètres du régime de traitement ont été optimisés. Ces derniers ont été appliqués sous différentes passes afin d’observer le comportement de "Sdq" avec la variation du nombre de passes et vis-à-vis de "Df". Les résultats montrent que "Sdq" diminue au fur et à mesure que "Df" ; avec l’augmentation du nombre de passes où il est observé pour i= 1, Df= 1.16 et Sdq=0.60µm et pour i= 3, Df= 1.08 et Sdq=0.24µm. Voir les détails

Mots clés : dimension fractale, pente quadratique de surface, optimisation, plans d’expérience

Traitement mécanique de surface- Approche par la dimension fractale

M. BOUREBIA, L. Laouar, H. Bounezour (2017)
Article de conférence

L’obtention d’une surface de qualité réside dans le choix du processus de finition le mieux adapté et le plus efficace à long terme, [18]. En effet, les traitements mécaniques de surface (TMS) sont des procédés de finition, qui opèrent sans perte de matière et contribuent énormément dans l’amélioration de la qualité des surfaces. Le brunissage à la bille est l’un de ces procédés, très simple et peu coûteux, il agit par déformation plastique des couches superficielles engendrant une amélioration des caractéristiques mécaniques et micro-géométriques de la surface. En conséquence les paramètres caractérisant l’état de surface sont directement liés aux processus de fabrication et de finition des surfaces. Souvent, la qualité de surface est caractériser par le paramètres statistique "Ra". Cependant l’inconvénient majeur de ce paramètre est qu’il n’est pas un bon indicateur pour les différents types de surfaces (aucune distinction n'est faite entre les pics et les vallées), et ne reflète pas une image fidèle et physique du profil de la surface réelle. Pour remédier ce problème, l’état de surface a été appréhendé par la dimension fractale "Dfs", ce paramètre permet de mesurer le degré des régularités de surface et reste constant à toute les échelles. Il prend des valeurs fractionnaires (2 < Df <3), plus "Dfs" tend vers 2 plus la surface est régulière et lisse. Afin d’observer l’effet des paramètres du régime de traitement sur la dimension fractale, un travail expérimental a été mené au moyen d’un procédé de traitement mécanique de surface (brunissage à la bille) appliqué sur un matériau en alliage d’aluminium commercial. Trois paramètres du régime ont été considérés à savoir : l’avance "f", la force de pression "Py" et le diamètre de la bille "Db". Des modèles mathématiques ont été dégagés en utilisant les plans d’expériences multifactorielles de "Box-Behenken" pour la prédiction de la dimension fractale "Dfs" .Voir les détails

Mots clés : Brunissage, état de surface, dimension fractale, plans d’expériences

Effects of work hardening on mechanical metalproperties—experimental analysis and simulation by experiments

Hichem Bounezour Lakhdar Laouar Mounira Bourebia Bousaid Ouzine (2019)
Article de journal

The aim of the present work is to improve the materials’ performances, particularly their elastic property based on an optimalexploitation of surface work-hardening phenomenon, using surface plastic deformation treatment (DPS). The surface of amechanical piece is considered as the most vulnerable zone that determines its mechanical performances. To improve thesurface physico-mechanical properties, the surface plastic deformation treatment (DPS) is often used. The (DPS) acts by acombined action of: surface hardening, structural modification, and the generation of the compression residual stresses, thefactors that will create a heterogeneous plastic deformation. Knowing that during operation the mechanical pieces have to besubjected to a stress smaller than the elastic limit (taking into account the safety margins), where the material behavior isreversible, and to reach the maximum allowable stresses, we have to increase the material’s elastic limits. This objective canbe realized through an optimal use of work hardening phenomenon for the treated surface by the DPS. The work hardening ischaracterized by the increase of the yield strength (Re), the surface hardness (Hv), and consequently the increase of thebrittleness. Depending on the considered metals, when the piece has a defect variation: cavity, inclusion (precipitate), orzones of different hardness, it can create a stress concentration which generates a local hardening. This phenomenon is one ofthe main causes of crack generation. In our study, we consider the influence of work hardening on the elastic behavior ofXC38 steel and aluminum alloy.Voir les détails

Mots clés : Work hardening . Hardening of materials . Mechanical surface treatment (TMS) . Burnishing

Study of the effect burnishing on superficial hardness and hardeningof S355JR steel using experimental planning

M. BOUREBIA, A. Bouri, H Hamadache, S. Achouri, L. Laouar, A. GHARBI, O. GHELLOUDJ, K. BOUHAMLA (2019)
Article de journal

Surface hardness plays an important role in lifetime of a mechanical piece subjected to friction and wear. Indeed, thehardness can be improved by superficial plastic deformation processes (SDP), such as mechanical surface treatment"MST", in particular the ball burnishing. However, the treatment result of is conditioned by mastery of operationthus ensuring treated piece good mechanical and geometric properties. Experimental work was carried out byapplying the ball burnishing process on steel tensile specimens S355JR, in order to observe the influence oftreatment parameters regime on surface hardness 'Hv' and the effect of latter on tensile behavior of this steel. Twoparameters of regime were considered namely: burnishing force "Py" and number of passes "i". The relationshipbetween these parameters and microhardness measured at "Hv" surface has been highlighting using factorial plans22. Moreover a mathematical model has been obtained allowing prediction of response (Hv) as well as optimizationof parameters of treatment regime. The experimental results showed that for surface hardness Hv it is possible toreach a 45% improvement rate for a burnishing force py = 20 Kgf and a number of passages i = 3 for this material.Regarding behavior of material during tensile test, for a low burnishing force (py = 10N) and a number of passes (i= 5), the section further weakening (S = 4.14), proof than ductility of material has decreased.Voir les détails

Mots clés : Surface hardness, factorial designs, ball burnishing, Mathematical model, tensile behaviour

Soudage hétérogène de deux aciers à hautes limites élastiques HSLA(X70) : Étude du comportement mécanique

Boukhalfa Sami DAHMOUN  (2014)
Mémoire de Master

L’assemblage des matériaux par soudure hétérogène occupe une place importante dans l’univers de l’industrie. Bien précisément les aciers inoxydables sont plus utilisables vu leur bonne soudabilité par tous les procèdesde soudage à l’arc. L’objectif de cette étude est la caractérisation microstructurale et mécanique d’une soudure hétérogène de deux couples d’aciers (HSLA). Les résultats obtenus montrent que la zone fondue de l’électrode austénitique subit un durcissement avec une résistance au choc élavé par rapport à la zone de l’électrode faiblement allié, ainsi, on a constaté que l'acier qui contient le tanneur bas de carbone possède le meilleur comportement mécanique. Voir les détails

Mots clés : HLE, SMAW, 308L, Soudure hétérogène.

A Simple Isoparametric Finite Element Based on the Reddy’s Theory for the Laminated Plates Bending Analysis

K. BELKAID, B. BOUBIR, A. Guenanou, H. Aouaichia (2018)
Article de conférence

The aim of this work is to develop a quadrilateral finite element based on Reddy’s third order shear deformation theory for the bending behavior analysis of composite laminated plates. The element is a C0 four-nodded isoparametric with seven degrees of freedom at each node, three translation components, two rotations and two higher order rotational degrees. In particular, selective numerical integration is introduced in order to improve the results and to alleviate the locking phenomenon. The performance and reliability of the proposed formulation are demonstrated by comparing the author’s results with those obtained using the three-dimensional elasticity theory, analytical solutions and other advanced finite element models.Voir les détails

Mots clés : Ajout mot cléThird Order Shear Deformation Theory, Ajout mot cléLaminated Composite Plates, Ajout mot cléFinite Element, Bending Behavior

Correlation between defect depth and defect length through a reliability index when evaluating of the remaining life of steel pipeline under corrosion and crack defects.

Djamel Zelmati, Oualid GHELLOUDJ, Abdelaziz AMIRAT (2017)
Article de journal

Despite the various engineering models existing for lifetime investigation of hydrocarbon steel pipelines under localized corrosion and crack defects there is still a lack of information about the correlation between the two main parameters characterizing the geometrical defect model, depth and length. So the aim of the present work is a contribution in evaluating the remaining life of the pipeline using reliability analysis in order to correlate the two parameters through one common parameter, the reliability index. As a first step, the investigation is carried out on four standard and well established engineering models; Irwin, SINTAP, ASME B31G and Modified ASME B31G methods, aiming to coordinate results given by each of the four models. The potential defect depth and length correlation through a reliability index can be used as a decision-making tool to give realistic answers for replacing and/or repairing a tube subjected to internal pressure and on which flaws of different depths and lengths have been detected from inspection of a pipeline after few years of service.Voir les détails

Mots clés : corrosion, Defect, Reliability, Correlation, Sensitivity