Abstract This study aimed to prevent the harmful consequences of the turning process. The use of micro-textured cutting inserts with a femtosecond laser an innovative efficient method to decrease chip adhesion to cutting of edge tools... more
Abstract This study aimed to prevent the harmful consequences of the turning process. The use of micro-textured cutting inserts with a femtosecond laser an innovative efficient method to decrease chip adhesion to cutting of edge tools during titanium alloy (Ti6Al4V) turning was studied. Additionally, the effects of different micro-pattern geometries and sizes on the machining capacity of coated WC/Co cutting inserts in turning experiments with titanium–aluminium–nitride (TiAlN) were investigated based on various lubrication processes. The surface states of the micro-patterned TiAlN-coated inserts were analysed using scanning electron microscopy and optical microscopy. Subsequently, machining and measured tests on the titanium alloy were performed using the developed cutting tools. Tungsten carbide tools with textured cutting surfaces and different microstructures were fabricated, and their behaviours were compared with those of conventional coated tools. Thrust, cutting, and feed cutting force values were measured during machining using a three-component dynamometer. Based on the present investigation, the cutting tool with a cross texture exhibited greater reduction of machining forces, friction coefficients, and tool wear.
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Ce travail presente une etude sur la surveillance des roulements par l’analyse vibratoire. Les vibrations sont des phenomenes physiques utilises pour mettre en evidence les defauts de fonctionnement ou de degradation d’une machine... more
Ce travail presente une etude sur la surveillance des roulements par l’analyse vibratoire. Les vibrations sont des phenomenes physiques utilises pour mettre en evidence les defauts de fonctionnement ou de degradation d’une machine tournante et donnent une meilleure mesure de son etat. La detection de la deterioration precoce d’un roulement est mise en evidence par l’utilisation d’un indicateur de defaut statistique temporelle qui est le kurtosis. Cette approche permet de developper une nouvelle forme de maintenance communement appelee maintenance conditionnelle
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Purpose The purpose of this paper is to highlight the performance of the Chaboche model in relation to the database identification, tests with imposed deformations were conducted at room temperature on 304L stainless steel specimens.... more
Purpose The purpose of this paper is to highlight the performance of the Chaboche model in relation to the database identification, tests with imposed deformations were conducted at room temperature on 304L stainless steel specimens. Design/methodology/approach The first two tests were performed in tension-compression between ±0.005 and ±0.01; in the third test, each cycle is composed of the combination of a compression tensile cycle between ±0.01 followed by a torsion cycle between ±0.01723 (non-proportional path), and the last, uniaxial ratcheting test with a mean stress between 250 MPa and −150 MPa. Several identifications of a Chaboche-type model were then performed by considering databases composed of one or more of the cited tests. On the basis of these identifications, the simulations of a large number of ratchet tests in particular were carried out. Findings The results present the effect of the optimized parameters on the prediction of the behavior of materials which is reported in the graphs, Optimizations 1 and 2 of first and second tests and Optimization 4 of the third test giving a good prediction of the increasing/decreasing pre-deformation amplitude. Originality/value The quality of the model's predictions strongly depends on the richness of the database used for the identification of the parameters.
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Ce travail presente une investigation numerique a l’echelle microstructurale, d’un alliage metallique a transition de phase solide/solide ou acier TRIP (Transformed Induced Plasticity). Un modele micromecanique bidimensionnel est... more
Ce travail presente une investigation numerique a l’echelle microstructurale, d’un alliage metallique a transition de phase solide/solide ou acier TRIP (Transformed Induced Plasticity). Un modele micromecanique bidimensionnel est implantee dans un code de calcul par elements finis (ZEBULON), pour simuler la transformation martensitique dans un grain de l’acier Fe-Ni-C. Deux cas de chargements sont utilises, une compression appliquee durant toute la transformation, puis une traction imposee du debut jusqu’a 80% de la transformation martensitique, suivie d’une charge de compression sur les 20% du temps restant de la transformation. Les effets du joint de grain non uniforme, du critere de la force mecanique de cisaillement (FMC) ainsi que de la direction du cisaillement des plaquettes sur les parametres de la transformation martensitique, ont ete etudies. Il a ete constate que le critere mecanique propose (FMC) favorise l’influence du phenomene de glissement dans l’avancement de ce type de transformation (mecanisme de Magee). Les resultats obtenus montrent bien que la forme du joint de grain, la direction de cisaillement des plaquettes et le critere mecanique (FMC), ont une grande influence sur les parametres de la transformation, c’est-a-dire, la cinetique, le sens d’ecoulement plastique et la valeur du TRIP.
Research Interests: Physics and Humanities
... Edwards, MF, and Wilkinson, WL (1984) Plate Heat Exchangers, HTFS Design Report DR36. ... I. Ouazia, B., Snelson, WK, Didsbury, RL, and Wadekar, VV (1994) Liquid-Liquid Heat Transfer in a Plate Heat Exchanger, HTFS Research Reports... more
... Edwards, MF, and Wilkinson, WL (1984) Plate Heat Exchangers, HTFS Design Report DR36. ... I. Ouazia, B., Snelson, WK, Didsbury, RL, and Wadekar, VV (1994) Liquid-Liquid Heat Transfer in a Plate Heat Exchanger, HTFS Research Reports RS961. ...
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Laser-assisted diffusion of phosphorus dopants has been investigated to realize selective emitters on mc-Si wafers. In this paper, we studied, in the presence of PSG, the effect of laser speed and power doping parameters on the sheet... more
Laser-assisted diffusion of phosphorus dopants has been investigated to realize selective emitters on mc-Si wafers. In this paper, we studied, in the presence of PSG, the effect of laser speed and power doping parameters on the sheet resistance RSq variation as a function of selective emitter formation. Four point-probe (FPP) measurements showed that 5.5–10 W with speed 100–1500 mm s−1 are, respectively, the best power values to form a selective emitter with 20–40 Ω/□ typical values. Electrochemical Capacitance-Voltage (ECV) results showed that dopant concentration and junction depth increased with decreasing scan speed, resulting in lower sheet resistances. Thus, the greater the difference between the concentration of starting phosphorus and that created by laser treatment, the smaller the square RSq will be. Scanning Electron Microscopy (SEM) images demonstrated more pronounced patterns of laser ablation when the power is high and/or the scanning speed is low.
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In the present study, the influence of variation of notch parameters on the notch stress intensity factor KI is studied using CT- specimen made from steel construction. A semi-elliptical notch has been modeled and investigated and is... more
In the present study, the influence of variation of notch parameters on the notch stress intensity factor KI is studied using CT- specimen made from steel construction. A semi-elliptical notch has been modeled and investigated and is applied to finite elements model. The specimen is subjected to a uniform uniaxial tensile loading at its two ends under perfect elastic-plastic behavior. The volumetric method and the Irwin models are compared using a finite elements method for determined the effective distance, effective stress and relative gradient stress which represent the elements fundamentals of volumetric method. Changing made to notch parameters affect the results of stress intensity factor and the outcomes obtained shows that the increase in size of minor axis reduces the amplitude of elastic-plastic stresses and effective stresses. In lengthy notches, the Irwin model remains constant with very little disturbance of outcomes.
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The first objective of this paper investigates the influence of the previous strain history on ratcheting of the 304 L stainless steel on ambient temperature. The identification is done using the Chaboche constitutive model. New tests... more
The first objective of this paper investigates the influence of the previous strain history on ratcheting of the 304 L stainless steel on ambient temperature. The identification is done using the Chaboche constitutive model. New tests were performed where different strain-controlled histories have been applied prior to ratcheting tests. It is demonstrated that under the same conditions, one can observe ratcheting, plastic shakedown or elasticity according to the prior strain-controlled history. The second objective points out the correlation between the experimental data base devoted to the identification of the material parameters and the quality of the predictions in cyclic plasticity. The results suggest that the choice of the tests should be closely linked to the capabilities of the model. In particular, the presence of non proportional strain-controlled tests in the data base may be not a good choice if the model itself is not able to represent explicitly such a character.Copyright © 2012 by ASME
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Dans le présent travail nous analysons numériquement l'effet du critère de la force mécanique de cisaillement (FMC) sur le comportement d'un alliage métallique à transition de phase austénite-martensite, ou acier TRIP (Transformed... more
Dans le présent travail nous analysons numériquement l'effet du critère de la force mécanique de cisaillement (FMC) sur le comportement d'un alliage métallique à transition de phase austénite-martensite, ou acier TRIP (Transformed Induced Plasticity). Ce critère, il donne l'ordre de succession de la formation des plaquettes de martensite (variante), en favorisant l'influence du phénomène de cisaillement dans l'avancement de ce type de transformation martensitique (mécanisme de Magee), en un mono grain. Un modèle implanté dans un code de calcul par éléments finis (ZEBULON) a été développé pour l'étude du comportement mécanique à l'échelle microscopique. Les résultats obtenus, montre que la cinétique et la valeur de la TRIP finale obtenues sont en bonnes concordance avec les résultats expérimentaux. In the present work we numerically analyze the effect of the shear mechanical force (SMF)criterion on the behavior of a metal alloy phase transition austenite-m...
Ce travail traite de l’ecrouissage et l’analyse du comportement macroscopique phenomenologique non lineaire de l’acier inoxydable austenitique 304L, soumis a un chargement mecanique cyclique multiaxial de traction/ torsion a ... more
Ce travail traite de l’ecrouissage et l’analyse du comportement macroscopique phenomenologique non lineaire de l’acier inoxydable austenitique 304L, soumis a un chargement mecanique cyclique multiaxial de traction/ torsion a deformation et a contrainte imposees. On evoquera ainsi la manifestation de deux phenomenes : sur-ecrouissage et Rochet. Un essai comparatif entre Rochet 1D et 2D ayant la meme contrainte moyenne a ete discute. Le comportement du materiau sous chargement cyclique est modelise en utilisant le modele de Chaboche..
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This research presents a design of experiments for early detection of bearing defects. Two measurement techniques (vibration and acoustic emission) are compared by using the ANOVA analysis. The results show the relationship between some... more
This research presents a design of experiments for early detection of bearing defects. Two measurement techniques (vibration and acoustic emission) are compared by using the ANOVA analysis. The results show the relationship between some time indicators to the degradation stage of bearing. The experimental design was considering the influence of the shaft speed, loadand defect size as independent variables while the dependent variables brought on different time indicators. The objective of this study is to compare the effectiveness, consistency and reliability for bearing defect monitoring by using vibration and acoustic emission measurements. The results lead us to favor the application of vibration because it adapts better to the vast majority of situations, while the acoustic emission allows for the reliable detection of the fault but not for accurate tracking. In fact, acoustic emission is recommend in the case of low speeds less than 400 rev/min. A new indicator called TALAF is ...
Ce travail presente une investigation numerique a l’echelle microstructurale, d’un alliage metallique a transition de phase solide/solide ou acier TRIP (Transformed Induced Plasticity). Un modele micromecanique bidimensionnel est... more
Ce travail presente une investigation numerique a l’echelle microstructurale, d’un alliage metallique a transition de phase solide/solide ou acier TRIP (Transformed Induced Plasticity). Un modele micromecanique bidimensionnel est implantee dans un code de calcul par elements finis (ZEBULON), pour simuler la transformation martensitique dans un grain de l’acier Fe-Ni-C. Deux cas de chargements sont utilises, une compression appliquee durant toute la transformation, puis une traction imposee du debut jusqu’a 80% de la transformation martensitique, suivie d’une charge de compression sur les 20% du temps restant de la transformation. Les effets du joint de grain non uniforme, du critere de la force mecanique de cisaillement (FMC) ainsi que de la direction du cisaillement des plaquettes sur les parametres de la transformation martensitique, ont ete etudies. Il a ete constate que le critere mecanique propose (FMC) favorise l’influence du phenomene de glissement dans l’avancement de c...
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In this work a study was carried out to analyze the effect of changes in parameters characterizing the notch, such that the radius and angle, on the evolution of plastic zone near of notch root. A steel CT specimen under uni-axial loading... more
In this work a study was carried out to analyze the effect of changes in parameters characterizing the notch, such that the radius and angle, on the evolution of plastic zone near of notch root. A steel CT specimen under uni-axial loading is taken as a finite element model. Two theoretical approaches are applied to calculate the extent of the plastic zone for different values of angle and notch radius using the volumetric and Irwin approaches. The elastoplastic analysis was used to determine the effective distance and the relative stress gradient by applying the finite element method (FEM). The size of the effective plastic zone deduced from elastic calculation reaches its maximum when the radius is close to zero and angle equal to zero. The variation of the angle modifies the notch extended plastic zone.
This work relates to the characterization with indentation of the hard chromium coatings, carried out by electrolytic way on a steel substrate. Steel thus covered is used for the construction of the jacks of industrial machines. We... more
This work relates to the characterization with indentation of the hard chromium coatings, carried out by electrolytic way on a steel substrate. Steel thus covered is used for the construction of the jacks of industrial machines. We studied in this work the effect of size which can be due to the preparation of surfaces and which it is necessary to dissociate from a real effect of size related to the movements of dislocations for the vicinity of the free face. The effect of size of the print or the effect of load on the value of hardness with the indenter Vickers is thus studied for various preparations of surfaces, on samples polished by various processes and with or without lubrication. It was shown that pleating mainly masks the phenomenon of the effect of load and hardness and that the presence of an oil film enters the indenter and the material to be tested, led to a significant reduction in hardness. When the test of indentation is carried out with the interface of a coating and its substrate, it is p...
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Purpose The purpose of this paper is to highlight the performance of the Chaboche model in relation to the database identification, tests with imposed deformations were conducted at room temperature on 304L stainless steel specimens.... more
Purpose The purpose of this paper is to highlight the performance of the Chaboche model in relation to the database identification, tests with imposed deformations were conducted at room temperature on 304L stainless steel specimens. Design/methodology/approach The first two tests were performed in tension-compression between ±0.005 and ±0.01; in the third test, each cycle is composed of the combination of a compression tensile cycle between ±0.01 followed by a torsion cycle between ±0.01723 (non-proportional path), and the last, uniaxial ratcheting test with a mean stress between 250 MPa and −150 MPa. Several identifications of a Chaboche-type model were then performed by considering databases composed of one or more of the cited tests. On the basis of these identifications, the simulations of a large number of ratchet tests in particular were carried out. Findings The results present the effect of the optimized parameters on the prediction of the behavior of materials which is rep...
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A single edge notched specimen is commonly used in materials of steel construction for the determination the notch stress intensity factor. CT- specimen is considered as a finite element model containing an elliptical notch under a... more
A single edge notched specimen is commonly used in materials of steel construction for the determination the notch stress intensity factor. CT- specimen is considered as a finite element model containing an elliptical notch under a uniform uni-axial tensile loading. The volumetric method is applied in perfect elastic-plastic behavior. Changing made to notch parameters influences the evaluation of the effective stress accordingly the results of the notch stress intensity factor.
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This paper is devoted to the study of the role of identification data base on the prediction of the cyclic behavior of the 304 L stainless steel on ambient temperature. The identification is done using the Chaboche constitutive model. The... more
This paper is devoted to the study of the role of identification data base on the prediction of the cyclic behavior of the 304 L stainless steel on ambient temperature. The identification is done using the Chaboche constitutive model. The investigations have been performed with reference to both unixial and biaxial experimental data, strain controlled tests, ratchet tests, ratchet tests after a strain controlled strain tests. Results were reported in graphs representing the effect of the optimized parameters on the prediction of the behavior of the material. The parameters of the Chaboche model have been calculated from the curve of a unixial strain controlled test. Then they were optimized using different data base on ZeBuLoN. The simulation obtained by optimized parameters gives a good representation of stabilised loop in the way it is done with the simulated test. Ratchet was also well predicted in the case of optimization done with all tests considered in the simulation. In this paper it has been demonstrated that the optimization using different data bases have a big impact on the cyclic results and ratchet results.