M. MAKRI Hocine

Prof

Directory of teachers

Department

Departement of MECHANICAL ENGINEERING

Research Interests

Materials science mechanical behavior machinning mechanical design

Contact Info

University of M'Sila, Algeria

Email : hocine.makri@univ-msila.dz

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Recent Publications

2024-11-13

ELABORATION AND CHARACTERIZATION OF CU-ZN-AL SHAPE MEMORY ALLOYS

The study examines Cu-Zn-Al shape memory alloys, vital in aeronautics and automotive sectors. It aims to characterize their thermo-mechanical transformations induced by composition and heat treatments, focusing on how these impact mechanical properties, especially grain size refinement. Analysis covers transformation temperatures, micro-hardness, induced
transformations, and mechanical tests. Results show thermoplastic martensitic transformations, with micro-hardness aiding in identifying characteristic points. The study's novelty lies in
understanding how grain size refinement affects these transformations and the role of microhardness in precise characterization
Citation

M. MAKRI Hocine, (2024-11-13), "ELABORATION AND CHARACTERIZATION OF CU-ZN-AL SHAPE MEMORY ALLOYS", [national] Pollack Periodica , Pollack Periodica-Akademiai Kiado

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2024-09-04

Investigation on the Mechanical Behavior of Date Palm Fibers Reinforced Composites: Predictive Modelling Using Artificial Neural Networks (ANNs)

This paper aims to strengthen composites by treated and untreated date palm fibers (PDF), with sodium hydroxide (NaOH), for light applications. With 75% cellulose content and a density of 1.2 g/cm3, the palm fibers were exposed to a preparatory treatment with 1.5% NaOH for 24 h prior to integration into a polyester. Four polyester samples comprising 30% of palm fiber were manufactured. Additionally, the palm fiber interface was evaluated using scanning electron microscopy (SEM) and optical microscopy. The specimens underwent mechanical testing and it shows that tensile (18% increase in stress and 1.2% increase in Young’s modulus) and flexural properties (20% increase in strength and 10% increase in Young’s modulus) of treated composites as compared with untreated fibers. A MATLAB-based Artificial Neural Network (ANN) model was applied to estimate stress and strain at break as well as the Young’s modulus, based on three input characteristics: section, sample length, and chemical treatment. It was obtained that the polyester reinforced by NaOH-treated palm fibers increased the mechanical characteristics relative to the untreated fibers. The coefficient of determination R3 in the ANN models is 0.87. These results suggest that the ANN model is a useful tool for predicting mechanical properties.
Citation

M. MAKRI Hocine, (2024-09-04), "Investigation on the Mechanical Behavior of Date Palm Fibers Reinforced Composites: Predictive Modelling Using Artificial Neural Networks (ANNs)", [national] Journal of Natural Fibers , Francis and Taylor

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2024-08-20

Effect of alkali treatment on new lignocellulosic fibres from the stem of the Aster squamatus plant

This research aims to examine the physical, structural and chemical properties of Aster Squamatus (AS) fibres, which are commonly found in Algeria, Brazil, France and the West Indies. In this work, we assess their appropriateness as reinforcing fillers to fabricate components for polymer composites principally designed for lightweight applications. To accomplish this objective, an extraction of fibres from plants modification of AS fibres and characterization of both untreated fibres (UASFs) and alkali-treated AS fibres (TASFs) are conducted. We analysed the crystallinity, chemical composition, thermal characteristics, and mechanical properties of AS fibres as per standard methods. It's clear from chemical treatment that amorphous components were successfully eliminated from the AS fibres, including hemicellulose, lignin, and wax. Consequently, the fibres' thermal, physical, and mechanical characteristics including Young's modulus, tensile strength, crystalline index, and surface roughness were substantially enhanced. It was determined that the fibres possessed a thermal stability of around 250 °C, with the maximal degradation temperature rising from 372.50 to 375.35 °C. The maximum stress rose from 183.24 ± 25.27 to 302.00 ± 24.91 MPa, the Young's modulus increased from 11.08 ± 1.1 to 18.53 ± 1.45 GPa, and the crystallinity index increased from 43% to 45%. Two-parameter Weibull statistics showed a strong link between experimental data and mechanical features of the twenty samples. We concluded from this work that AS plant fibres can serve as a robust reinforcing material in polymer composites for various applications.
Keywords: Aster squamatus fibres; Composites; Alkali treatment; Morphological properties; Thermal properties; Tensile test; Weibull statistics
Citation

M. MAKRI Hocine, (2024-08-20), "Effect of alkali treatment on new lignocellulosic fibres from the stem of the Aster squamatus plant", [national] Journal of Materials Research and Technology , Elsevier

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2024-04-10

Assessment of mechanical and physicochemical properties of palm fiber composites: Effect of alkaline treatment and volume alterations

This study assesses the impact of alkaline treatments and volume fractions on biocomposites composed of a high-density polyethylene (HDPE) matrix reinforced with date palm tree fibers (FPDS). Tensile tests were conducted on both untreated and NaOH-treated biocomposites. Additionally, fiber analysis was performed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results reveal higher strength and stiffness compared to HDPE, albeit with limited plasticity making the material brittle. The NaOH treatment enhances certain mechanical properties. Further assessments encompassed hardness, density, melt index, and Izod impact tests. Two volume fractions, 20% and 25%, of FPDS were tested. The study establishes a correlation between empirical predictions and artificial neural network (ANN) models.
Notably, an ANN architecture consisting of two input factors, 10 hidden nodes, and one output provides the analysis of mechanical properties. This investigation highlights the potential of FPDS-reinforced HDPE biocomposites, emphasizing their mechanical performance under various treatments and fiber levels.
Citation

M. MAKRI Hocine, (2024-04-10), "Assessment of mechanical and physicochemical properties of palm fiber composites: Effect of alkaline treatment and volume alterations", [national] Journal of Composite Materials , Elsevier

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2024-03-15

Calibration strategies for enhancing accuracy in serial industrial robots for orbital milling applications

This research paper aims to optimize the calibration process for an ABB IRB 120 robot, specifically for robotic orbital milling applications, by introducing and validating the use of the observability index and telescopic ballbar for accuracy enhancement.
Design/methodology/approach
The study uses the telescopic ballbar and an observability index for the calibration of an ABB IRB 120 robot, focusing on robotic orbital milling. Comparative simulation analysis selects the O3 index. Experimental tests, both static and dynamic, evaluate the proposed calibration approach within the robot’s workspace.
Findings
The proposed calibration approach significantly reduces circularity errors, particularly in robotic orbital milling, showcasing effectiveness in both static and dynamic modes at various tool center point speeds.
Research limitations/implications
The study focuses on a specific robot model and application (robotic orbital milling), limiting generalizability. Further research could explore diverse robot models and applications.
Practical implications
The findings offer practical benefits by enhancing the accuracy of robotic systems, particularly in precision tasks like orbital milling, providing a valuable calibration method.
Social implications
While primarily technological, improved robotic precision can have social implications, potentially influencing fields where robotic applications are crucial, such as manufacturing and automation.
Originality/value
This study’s distinctiveness lies in advancing the accuracy and precision of industrial robots during circular motions, specifically tailored for orbital milling applications. The innovative approach synergistically uses the observability index and telescopic ballbar to achieve these objectives.
Keywords
Citation

M. MAKRI Hocine, (2024-03-15), "Calibration strategies for enhancing accuracy in serial industrial robots for orbital milling applications", [national] Industrial Robot , Emerald Publishing Limited

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2023-12-14

Experimental investigation of the delamination behavior of glass-fibre reinforced composite pipes

Despite the many benefits that have expanded the field of fiber-reinforced composites applications, they remain vulnerable to failure by fold separation, a
failure mode known as delamination. In some applications, fiber-reinforced composites come in the form of tubes for civil use in the underground transport of
liquids. Usually these pipes are manufactured using a filament winding technique. Thus, an appropriate selection of the winding angle is therefore required to enhance
the delamination resistance. In this paper, the effect of the winding angle and the initial crack length on the delamination behavior of vinyl ester resin-fiberglass
composites was investigated experimentally. Accordingly, DCB samples with different winding angles (±45°, ±55° and ±65°) were cut from pipes of 08folds manufactured by the filament winding technique and then subjected to tests under mode-I loading. Previously, initial cracks of 50mm and 100mm length were created by the introduction of a thin film of polytetrafluoroethylene (PTFE) during the winding process. The mode-I fracture tests were conducted according to ASTM D5528-94a standards. Results show that the delamination resistance is enhanced with higher winding angles and lower initial crack lengths, respectively. The qualitative analysis shows that ±65° winding angle provides the best delamination resistance behavior compared to ±55° and ±45° winding angles
Citation

M. MAKRI Hocine, (2023-12-14), "Experimental investigation of the delamination behavior of glass-fibre reinforced composite pipes", [national] U.P.B. Sci. Bull., Series D , Politechnica University of Bucharest

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2023-10-23

Comprehensive study of the delamination of glass-fiber based composites.

In this paper, the effect of the winding angle and the number of folds on the delamination behavior of vinyl ester resin-fiberglass composites under mode-I loading was
investigated experimentally. Accordingly, double cantilever beam samples with 8 and 12 folds and with different winding angles (±45°, ±55° and ±65°) were cut out of industrial pipes and subjected to mechanical tests. Furthermore, thick films were introduced during the winding process to create initial cracks of 50mm. The Mode-I fracture tests were conducted according to ASTM D5528-94a standards. Results show that the [±65°] winding angle provides the best
delamination behavior and greater resistance to cracking compared to the [±55°] and [±45°] winding angles. Results also show that the number of folds has no effect on the initiation of the crack stage, but it significantly affects the propagation stage.
Citation

M. MAKRI Hocine, (2023-10-23), "Comprehensive study of the delamination of glass-fiber based composites.", [national] Academic Journal of Manufacturing Engineering , Editura Politehnica

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2023-10-01

COMPREHENSIVE STUDY OF THE DELAMINATION OF GLASS-FIBER BASED COMPOSITES

In this paper, the effect of the winding angle and the number of folds on the
delamination behavior of vinyl ester resin-fiberglass composites under mode-I loading was
investigated experimentally. Accordingly, double cantilever beam samples with 8 and 12 folds
and with different winding angles (±45°, ±55° and ±65°) were cut out of industrial pipes and
subjected to mechanical tests. Furthermore, thick films were introduced during the winding
process to create initial cracks of 50mm. The Mode-I fracture tests were conducted according to
ASTM D5528-94a standards. Results show that the [±65°] winding angle provides the best
delamination behavior and greater resistance to cracking compared to the [±55°] and [±45°]
winding angles. Results also show that the number of folds has no effect on the initiation of the
crack stage, but it significantly affects the propagation stage.
Citation

M. MAKRI Hocine, (2023-10-01), "COMPREHENSIVE STUDY OF THE DELAMINATION OF GLASS-FIBER BASED COMPOSITES", [national] ACADEMIC JOURNAL OF MANUFACTURING ENGINEERING , ACADEMIC JOURNAL OF MANUFACTURING ENGINEERING

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2023-09-26

Microstructure investigation on low carbon steel joints arc welded

During welding operation, a thermal phenomenon related to the repeated process of non-uniform heating followed by cooling at room temperature. As a result, the microstructure of the weld bead and surrounding areas of the base metal are modified and are partially affected by the poorly heated area during welding. The object of this work concerns the microstructural and mechanical characterization of a welded joint with wire type SG2 carried out on micro alloyed ferritic base steel with low carbon (0.45% C). This commercial product is widely used in mechanical engineering in the machinery industry, cranes. Samples were cut from rough as hot-rolled sheet. A chemical analysis of the base metal was conducted to confirm the chemical composition previously provided. Mechanical polishing and chemical attack with Nital 3% followed by microstructural characterization by optical microscopy of the welds followed by micro hardness tests using an instrumented microdurometer. The results obtained make it possible to draw the following conclusions: In the bonding area where the thermal input is quite large and short, a grain size gradient was obtained, conditioned by the temperature gradient of the welding along the plates. In the melting zone, different structures are found conditioned by the cooling rate; for the large cooling rates, in the case of external passes: a characteristic needle structure of the out of equilibrium ferrite has been revealed. For passes heated several times, in the case of regenerated areas of the lower part of the weld joint; a ferritic structure of weidmanstatten with increasingly regular grains and for the internal passes of the intermediate part having undergone heating treatments; structures closer to the equilibrium state or to mixed textures of regular ferrite, due to the coalescence of ferrite needles. These results confirm the modification of the initial microstructure by thermal input during welding.
Citation

M. MAKRI Hocine, (2023-09-26), "Microstructure investigation on low carbon steel joints arc welded", [international] 3rd International Conference on Innovative Academic Studies ICIAS 2023 , TURKEY

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2023

Extraction and characterization of novel lignocellulosic fibers from Centaurea hyalolepis plant as a potential reinforcement for composite materials

The aim of this investigation is to evaluate the use of new lignocellulosic fiber extracted from Centaurea hyalolepis plant as a potential reinforcement for light-weight composite applications. In this study, anatomical structure and morphological surface of Centaurea hyalolepis fiber were conducted. The physical-chemical, thermal, crystalline,mechanical, characteristics of extracted fibers were also examined using Attenuated Total Reflectance-Fourier Transform Infrared (ATRFTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and tensile test. ATR-FTIR analysis confirmed the existence of the main components of lignocellulosic fiber (lignin, cellulose, and hemicellulose). XRD revealed the presence of cellulose with a crystallinity index of 57.93%.By densimetry, the density of Centaurea hyalolepis was determined as 1.13 g/cm3. The Centaurea hyalolepis was found to be thermally stable up to 271°C. The kinetic activation energy was determined as 115.943 kJ/mol. Tensile tests revealed that the mean tensile strength and Young’s modulus of Centaurea hyalolepis fiber were about 372,5 MPa and 9.036 GPa respectively. Because of the dispersion in the experimental tensile results, the Weibull statistical analysis with two parameters was carried out. Regard these findings, the Centaurea hyalolepis fibers can be a suitable candidate for low density polymeric composites reinforcement.
Citation

M. MAKRI Hocine, (2023), "Extraction and characterization of novel lignocellulosic fibers from Centaurea hyalolepis plant as a potential reinforcement for composite materials", [national] Journal of Composite Materials , SAGE

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2022

Evaluation of Temperature at the Interface of Pairs of Steels in Dry Sliding as a function of Hardness

This work presents a study of the determination of the temperature at the interface in the dry
friction of the low alloy steel pin against a medium-hard carbon steel disk. The parameters: Normal load
applied, sliding speed, hardness of the material and coefficient of friction resulting during the tribological
tests carried out play a very important role on the thermal effects of the opposing surfaces. The Archard
model was used to determine the temperature at the tribological couple interface, using the parameters
mentioned above.
Citation

M. MAKRI Hocine, (2022), "Evaluation of Temperature at the Interface of Pairs of Steels in Dry Sliding as a function of Hardness", [international] 1st International Conference on Scientific and Academic Research , Turkey

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Effect of Heat Treatment of Mechanical Tensile Characteristics of an Aluminum Alloy

In order to understand the mechanical behavior in tension of the aluminum alloy 6082, we carried
out an experimental study. After the samples (tensile specimens) were manufactured on the lathe according
to the standardized dimensions, they were heat-treated (solution treatment, water quenching and tempered
at different temperatures to have different hardness. Tensile tests were carried out by the tensile machine,
which allowed us to have experimental results and to understand the behavior of the aluminum alloy 6082
through its mechanical properties such as hardness, breaking strength, elongation and coefficient of
necking.
Citation

M. MAKRI Hocine, (2022), "Effect of Heat Treatment of Mechanical Tensile Characteristics of an Aluminum Alloy", [international] 2nd International Conference on Engineering and Applied Natural Sciences , Turkey

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Study of the Influence of Tempering Temperature on the Tensile Behavior of a Low Alloy Steel

The mechanical properties of steel are part of the necessary conditions to know for the proper
functioning of mechanical systems in industry. The objective of this work is the study of the mechanical
characteristics of low alloy steel AISI 4041. Considering an experimental approach based on the influence
of different heat treatments (quenching and tempering at different temperatures) on the behavior of the steel
studied in tension. The desired mechanical characteristics relate to hardness, breaking strength, elongation
and the coefficient of necking. After the tensile tests, it was observed that there is a reciprocity between the
tempering temperature on the one hand and the hardness of the material and the breaking strength on the
other hand. A certain proportionality noticed between the hardness, the elongation and the coefficient of
necking.
Citation

M. MAKRI Hocine, (2022), "Study of the Influence of Tempering Temperature on the Tensile Behavior of a Low Alloy Steel", [international] 2nd International Conference on Engineering and Applied Natural Sciences , Turkey

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Effect of winding angle and initial crack length on delamination in fiber reinforced composite tubes

Fibre-reinforced polymer composites have replaced many conventional materials, especially in liquid transport applications because of some of the advantages they offer. But when loaded, these materials present damage in the form of layer separation. This mode of degradation is known as delamination. The main objective of this experimental work is to study this behavior in Mode-I type loading, focusing the influence of the winding angle and the initial crack on the GIC interlaminar toughness for the case of composite material elements taken from tubes with transverse curvature.
For the experimental, DCB samples are tailored in 500mm-radius tubes of fibreglass vinyl ester resin based composite obtained by filament winding at different winding angles (45°, 55° and 65°) and having initial crack a0 of different length 50mm, and 100mm. A thin film of PTFE is interposed in the middle layer during the construction of the tubes as a crack initiator. Special loading devices were prepared and used to conduct the fracture tests in Mode-I in accordance with ASTM D5528-94a. The tests were performed on an INSTRON-5969 machine. The results obtained showed that the shorter the initial cracks, the greater the toughness of the interlaminar fracture, achieving an inverse relationship between the interlaminar fracture toughness and the length of the initial crack. The results also showed that the 65° winding angle confers a good behavior vis-à-vis delamination as the 55° and 45° angles.
Citation

M. MAKRI Hocine, (2022), "Effect of winding angle and initial crack length on delamination in fiber reinforced composite tubes", [international] 1st International Conference on Innovative Academic Studies. ICIAS2022. September 10 - 13, 2022, Konya, Turkey , Turkey

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Determination of mechanical properties of Alumina-Zirconia ceramic composites by instrumented indentations

The objective of the present work is to determine the mechanical properties of ceramic composites on the basis of load-discharge curves and crack-length measurements. For the purpose, ceramic composite samples were prepared from different mixtures of starting powders of boehmite (AlOOH) and zircon (ZrSiO4) by variation of the Boehmite to zircon weight ratios and then subjected to a reactive sintering in air at 1600°C. The sintered samples were characterized in terms of phase composition, relative density, microstructures and mechanical properties by Vickers indentation tests. Furthermore, the microstructure was related to mechanical properties. The effects of both initial powder ratios and sintering conditions on the hardness and fracture toughness were analyzed. The results showed the possibility to manufacture a ceramic material with desired phases, acceptable density and mechanical properties by varying the composition of the initial powders. The results also show that the increase in zirconia rate improves toughness but promotes the porosity which acts on the opposite of toughness and hardness but enhances elasticity. The use of load-unload curves for the determination of mechanical properties of ceramic materials is effective.
Citation

M. MAKRI Hocine, (2022), "Determination of mechanical properties of Alumina-Zirconia ceramic composites by instrumented indentations", [international] 3rdInternational Conference on Applied Engineering and Natural Sciences. ICEAENS2022. July 20-23, 2022, Konya, Turkey , Konya, Turkey

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2021-03-07

Dispositif de maintien en position d'usinage pour pièces cylindriques à parois mince

Il s'agit d'un dispositif de maintien en position d'usinage pour pièces cylindriques à parois mince lors de l'opération d'usinage
Citation

M. MAKRI Hocine, (2021-03-07), "Dispositif de maintien en position d'usinage pour pièces cylindriques à parois mince", [national] Université de M'sila

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2021

ETUDE DU DÉLAMINAGE DANS LES TUBES EN MATÉRIAUX COMPOSITES

Les composites multicouches en polymères renforcés de fibre de verre ont remplacé beaucoup de matériaux conventionnels dans les applications de transport de liquides à cause de certains avantages qu’elles offrent. Mais, lorsqu’ils sont chargés, ces matériaux sont vulnérables aux dommages menant à la séparation des couches. Ce mode de dégradation est connu sous le nom de délaminage. L’objectif principal de ce travail expérimental est d'étudier le comportement vis-à-vis du délaminage en Mode-I pour des éléments en matériaux composites
présentant un rayon de courbure et qui sont prélevés de tubes. Focalisant l’influence de l'angle d'enroulement et la fissure initiale sur la ténacité interlaminaire GIC. Pour atteindre cet
objectif, des échantillons DCB présentant a courbure sont réalisés à partir de tubes composites de 500mm de rayon fabriqués à partir de résine de vinyle ester et renforcé en fibre de verre élaborés par enroulement filamentaire selon différents angles d'enroulement (±45°, ±55° et ±65°) et comportant fissure initiale a0 de longueur différentes 50, et 100mm. Les pré-fissures sont réalisés par interposions d’un film mince de PTFE dans la couche médiane lors de l’élaboration des tubes. Des dispositifs de chargement spéciaux conformes aux normes ASTM D5528-94a ont été préparés et utilisés pour mener les essais mécaniques de rupture en mode-I. Les essais ont été réalisés sur une machine INSTRON-5969. Les résultats obtenus ont montré une relation inverse entre les valeurs de ténacité de la rupture interlaminaire et la longueur de la fissure c’est à dire, moins long sont les longueurs des pré-fissures plus grands sont les valeurs de la ténacité de la rupture interlaminaire et que l'angle d'enroulement ± 65° confère au matériau un bon comportement vis-à-vis du délaminage que les angles ± 55° et ± 45°.
Citation

M. MAKRI Hocine, (2021), "ETUDE DU DÉLAMINAGE DANS LES TUBES EN MATÉRIAUX COMPOSITES", [international] ETUDE DU DÉLAMINAGE DANS LES TUBES EN MATÉRIAUX COMPOSITES , oran

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Etude du délaminage dans les tubes en matériaux composites

Les composites multicouches en polymères renforcés de fibre de verre ont remplacé beaucoup de matériaux conventionnels dans les applications de transport de liquides à cause de certains avantages qu’elles offrent. Mais, lorsqu’ils sont chargés, ces matériaux sont vulnérables aux dommages menant à la séparation des couches. Ce mode de dégradation est connu sous le nom de délaminage. L’objectif principal de ce travail expérimental est d'étudier le comportement vis-à-vis du délaminage en Mode-I pour des éléments en matériaux composites présentant un rayon de courbure et qui sont prélevés de tubes. Focalisant l’influence de l'angle d'enroulement et la fissure initiale sur la ténacité interlaminaire GIC. Pour atteindre cet objectif, des échantillons DCB présentant a courbure sont réalisés à partir de tubes composites de 500mm de rayon fabriqués à partir de résine de vinyle ester et renforcé en fibre de verre élaborés par enroulement filamentaire selon différents angles d'enroulement (±45°, ±55° et ±65°) et comportant fissure initiale a0 de longueur différentes 50, et 100mm. Les pré-fissures sont réalisés par interposions d’un film mince de PTFE dans la couche médiane lors de l’élaboration des tubes. Des dispositifs de chargement spéciaux conformes aux normes ASTM D5528-94a ont été préparés et utilisés pour mener les essais mécaniques de rupture en mode-I. Les essais ont été réalisés sur une machine INSTRON-5969. Les résultats obtenus ont montré une relation inverse entre les valeurs de ténacité de la rupture interlaminaire et la longueur de la fissure c’est à dire, moins long sont les longueurs des pré-fissures plus grands sont les valeurs de la ténacité de la rupture interlaminaire et que l'angle d'enroulement ± 65° confère au matériau un bon comportement vis-à-vis du délaminage que les angles ± 55° et ± 45°.
Citation

M. MAKRI Hocine, (2021), "Etude du délaminage dans les tubes en matériaux composites", [national] 2. Séminaire international sur l’Industrie et la Technologie.12 et 13 Mars 2021. , Oran. Algeria

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2019

EXPERIMENTAL INVESTIGATIONS TO EVALUATE THE VALIDITY AND PERFORMANCE OF NDT PROCEDURES FOR IN-SERVICE INSPECTIONS

During multipass welding, cumulative and repetitive thermal phenomena may lead to development of cracks that can seriously compromise the quality of the welded joint. The use of Non-Destructive Testing methods is needed for the in-service inspection of the welded joint quality. To reliably evaluate the performance of an NDT procedure for in-service inspections, different types of artificial defects are used for this study. They have to be representative enough in comparison with the real service defects. For instance, thermal crack was realistically created by machining in a welded joint achieved by MAG welding deposition of melted SG3 wire on E36-3 steel, this case study being widely met in the crane industry. The approach consists of comparing two different ultrasonic techniques (Normal beam inspection and Angle beam inspection) in order to evaluate their performance in detecting and determining the size of well-known defects. Despite the difficulty in developing and interpreting the on-screen signals, caused by uncertainty in measuring the defect size, better results have been achieved when the angle beam inspection technique has been applied for the in-service inspections.
Citation

M. MAKRI Hocine, (2019), "EXPERIMENTAL INVESTIGATIONS TO EVALUATE THE VALIDITY AND PERFORMANCE OF NDT PROCEDURES FOR IN-SERVICE INSPECTIONS", [national] ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI, FASCICLE XII, Welding Equipment and Technology , Galati University Press

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2018

Caracterisation Microstructurale des Joints d’Acier 0.54% de Carbone Soudes a l’Arc.

Several phenomena occurring simultaneously in the welding operation, the thermal phenomenon related to the repeated non-uniform heating process followed by cooling at room temperature, affect the weld bead enormously and microstructurally modify the heat affected zone and its vicinity of the basic metal. The aim of this work concerns the microstructural and mechanical characterization of a SG2 alloy copper-welded joint made on a mainly micro-alloyed ferritic 0.54% carbon steel, widely used in construction in the gear industry, Cranes, samples were cut on a crude in the form of hot-rolled sheets provided by the Algerian company ACI-M'sila. A chemical analysis of the base metal to confirm the chemical composition was performed a microstructural characterization by optical microscopy of the welds were carried out followed by microhardness tests on an instrumented microdurometer. The results obtained make it possible to conclude that in the connection zone where the thermal input is brief and fairly important, a grain size gradient is encountered, so the grain size is conditioned by the gradient of the welding temperature along the sheets. Depending on the cooling rate in the melting zone, it can be seen that for the high cooling rate in the case of external passes, a needle structure characteristic of out-of-equilibrium ferrite is obtained. regenerating areas case of the lower part of the joint, a ferritic structure of weidmanstatten with grains more and more regular. For internal passes cases of the intermediate part having undergone reheating treatments, structures closer to the equilibrium state or to mixed textures of regular ferrite, due to the coalescence of the ferrite needles.
Citation

M. MAKRI Hocine, (2018), "Caracterisation Microstructurale des Joints d’Acier 0.54% de Carbone Soudes a l’Arc.", [international] International Seminar in Industrial Engineering and Applied Mathematics (ISIEAM'2018) , Skikda-Algeria

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2016

INVESTIGATION ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF E36-3 STEEL WELDED JOINT

The aim of the investigation was to find a liaison between materials chemicalcomposition, microstructure and mechanical properties for the E36-3 low alloy high
strength steel, also called low alloy structural steel. The base material widely usedin fabrication of gear and cranes from the Algerian company CIG Constantine waswelded with cored wire SG3 by the Gas Metal Arc Welding (GMAW) technique. The
behaviour of E36-3 steel in terms of metallurgical modifications, hardness and
Charpy V-notch impact in weld metal (WM), heat affected zone (HAZ) and base
metal (BM) was investigated and discussed. The experimental results highlighted theimpact of the welding process on the microstructure and mechanical properties. The
effect of the thermal cycles developed during welding on the microstructure was
reflected by the formation of various structures with various characteristics which,finally, have determined the mechanical properties of the welded joint. Besides, the
influence of the number of passes on the fusion weld microstructure was studied.
Inside the fusion weld, due to the effects produced by the repeated heating andcooling on the previous layers, a structure of pearlite and ferrite regenerated with
fine grains was developed, while in the case of the outer passes, a combination of
pearlite and acicular ferrite was obtained. The analysis of the fracture mechanismof the welded joints revealed the presence of ductile fracture, characterized bytearing of metal accompanied by appreciable global plastic deformation, at room
temperature. A severe decrease of the plasticity properties of the joint was observed
in the temperature range of (-20°C)...(-80°C).
Citation

M. MAKRI Hocine, (2016), "INVESTIGATION ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF E36-3 STEEL WELDED JOINT", [national] Annals of “Dunarea de Jos” University, Fascicle XII, Welding Equipment and Technology , Galati University

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2015

Zirconia transformation in multi-phases ceramic composites

Low cost composite ceramics based on zircon-mullite-zirconia-alumina phases were prepared by reaction sintering of boehmite (AlOOH) and zircon (ZrSiO4) powders. Boehmite to zircon weight ratios of the starting powders were varied (10 to 90 wt. %). The green compacts were made by uniaxial pressing at 7 MPa followed by cold isostatic pressing at 250 MPa. A reactive sintering in air of these compacts was made at different temperatures between 1400° and 1600°C during 2 hours. A quantitative evaluation of the present phases was based on XRD. Dilatometric tests on the reaction-sintered composites were carried out in order to study the zirconia phase’s transformations and their thermal expansion coefficient (). In addition, the effects of both boehmite/zircon ratios and sintering conditions on the mechanical properties (Hardness Hv, Elastic modulus E and fracture toughness KIC) of the obtained composites were characterized by Vickers indentation.
Citation

M. MAKRI Hocine, (2015), "Zirconia transformation in multi-phases ceramic composites", [national] Journal of The Australian Ceramic Society , Australian Ceramic Society

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2014

Elaboration and characterization of multiphase composites obtained by reaction sintering of boehmite and zircon

In this work, different composites (zircon–mullite–zirconia, mullite–zircon–zirconia, mullite–zirconia, mullite– zirconia–alumina and alumina–mullite–zirconia) were developed by reaction sintering of boehmite (AlOOH) and zircon (ZrSiO4). Several mixtures were used by varying the boehmite content from 10 to 90 wt. %. All powders were mixed and grounded by ball milling and then pressed in cylindrical form. Finally, the green specimens were sintered under normal conditions for 2 hours at temperatures between 1400 and 1600°C, with a heating rate of 5°C/min. The dilatometric curves reveal several microstructural transformations in these mixtures. The X-rays diffraction spectra revealed factors such as percentage of boehmite and zircon and the sintering temperature lead to the formation of several composites. The presence of the various phases was confirmed by micrographic observations.
Citation

M. MAKRI Hocine, (2014), "Elaboration and characterization of multiphase composites obtained by reaction sintering of boehmite and zircon", [national] Journal of the Australian Ceramic Society , Australian Ceramic Society

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