Publications Scientifiques
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Item Effect of Alternating Hybridisation of Fibres on the Physico - Mechanical Behaviour of Composite Materials(Sciendo, 2023) Harb, Noura; Dilmi, Hamid; Bezzazi, Boudjema; Hamitouche, KahinaThe performance/weight ratio of fiber reinforced polymer matrix composites makes them the material of choice for structural applications in many fields such as aerospace, aeronautics, automotive and civil engineering...etc. In polymer matrix composites, the fibers used as reinforcement are mainly synthetic fibers such as carbon and/or glass fibers. To ensure the low cost of using fiber- reinforced materials in motor vehicles, it is proposed to selectively incorporate carbon fibers to enhance glass fiber composites along the roadway, and to enhance glass fiber composites along the main load path. For this purpose, we conducted a behavioral study of hybrid epoxy thermoset polymer matrix laminates to highlight the influence of alternate hybridization of glass and carbon fibers on the physical- mechanical behavior of the materials.The results obtained show that the alternated hybridation of the fibers has a significant influence on the tensile properties ; and it affected the density, hardness and flexural properties significantly.Item Assessment of friction stir welding joints of aa2017-t4 aluminum by disc pressure mechanical tests(2023) Djili, Abderrahmane; Bezzazi, Boudjema; Haboussi, Mohamed; Zioui, NadjetPrecipitation hardening aluminium alloy sheets AA2017-T4 are welded by FSW on a conventional FSW tool. A macrograph of the cross section of the butt-welded joint shows the classical zones for such welding, namely the nugget zone, the thermo-mechanically affected zone and the heat affected zone. Scanning Electron Microscopy displays a grain refining and a re-formation of the precipitates in the nugget zone. Micro-hardness measurements on the cross-section perpendicular to the welding direction give the standard W-profile of the hardness for such welding, with as expected, the relatively highest value at the joint center (nugget zone). To assess the mechanical performance of the FSW welded joint, the Disk Pressure Test (DPT) is used. It shows a failure pressure for the welded specimen that is 17% lower than the base material. The fracture surface micrographs clearly show a thickness reduction at break that is ~36% higher for the base material than the welding joint and a ductile fracture mode for both specimens.Item Effect of natural aging on the tensile properties and the toughness of friction stir welds of 2024-T3 aluminum alloy(Elsevier, 2023) Djili, Abderrahmane; Bezzazi, Boudjema; Zioui, Nadjet; Haboussi, MohamedDuring friction stir welding of metallic alloys, four different microstructure zones are formed in the weld, resulting in heterogeneous mechanical properties in this latter. In the case of aluminum alloys, these properties are bound to change with aging, whether natural or artificial. In this study, changes in the toughness and tensile behavior of friction stir welds in Al 2024-T3 alloy over time are investigated. Only specimens found to be defect free, by X-ray imaging, are tested. Characterized by the area under the stress-strain curve of the material, the toughness is found to be 19% lower after 24 months of natural aging. This decrease in toughness is mainly due to a loss of ductility as the elongation of the material drops by 27% while the ultimate tensile strength increases by 9%. The fracture zone and pattern remain the same for both natural aged and freshly welded specimens. These results can be used to estimate the service life of structures using such a material, as in aeronautics.Item Elaboration Et Caractérisation Mécanique Quasi Statique D'un Composite Stratifie Jute/polyester(Université M'Hamed Bougara Boumerdes, 2014) Belkacemi, Cherifa; Bezzazi, BoudjemaLes matériaux composites renforcés par des fibres végétales sont en cours de développement, leurs applications sont encore limitées mais ils sont amenés à jouer un rôle dans l’industrie future. Parmi les fibres naturelles, se trouvent les fibres végétales, matériaux de qualité, qui se fabriquent et se recyclent naturellement sur terre depuis très longtemps (matériaux biodégradables et renouvelables par culture (jute). Dans le but d’avoir un matériau le moins coûteux possible et le plus performant se qu’en intéresse à la caractérisation d’un nouveau matériau composite de type stratifié à matrice de résine polyester et renfort naturel (jute).Ce matériau composite est destiné à être utilisé dans les domaines de la construction et du transport. A l’heure actuelle, un certain nombre d’équipes de chercheurs caractérisent plusieurs types de fibres naturelles afin de faciliter leur introduction dans les matrices thermodurcissables pour la fabrication des matériaux composites. Avant l’élaboration des stratifiées nous avons caractérisé le jute par l’essai de traction après nous avons élaboré ces stratifiées sous vide, ces derniers sont découpées selon les normes.Item The physicomechanical and thermal properties of Algerian Aleppo pine (Pinus halepensis) wood as a component of sandwich panels(SISEF - Italian Society of Silviculture and Forest Ecology, 2022) Lakreb, Nadia; Sen, Umut; Bezzazi, Boudjema; Pereira, HelenaAleppo pine (Pinus halepensis Mill.) is the main forest species of Algeria occu-pying more than 35% of the total forest area of the country. However, the physicomechanical and thermal characteristics of Algerian P. halepensis wood are not well-known. This research investigates the physical (moisture, density, swelling, and shrinkage), mechanical (bending strength and modulus of elastic-ity), and thermal (mass loss under combustion and pyrolysis as well as thermal conductivity) properties of P. halepensis wood from the Darguina (Bejaia) forest in Algeria. The results showed that Algerian P. halepensis wood with a mean density of 540 kg m-3 has good dimensional stability in swelling and shrinkage, with 116.43 MPa bending strength and a modulus of elasticity of 17,520 MPa. The wood shows a good thermal resistance under low-tempera-ture range and has a thermal conductivity of 0.21 W m-1 K-1. The overall results indicate that Algerian P. halepensis wood may be commercially exploited for construction and insulation applications, namely in the production of sandwich compositesItem Mechanical alloying of the fe-cr mixture and stabilization of the sintered nanostructure by carbon addition(Politechnica University of Bucharest, 2021) Amirouche, Saïfi; Bezzazi, Boudjema; Nechiche, Mustapha; Azem, SaidThe present work concerns the mechanical alloying of the iron-chromium mixture (Fe20% Cr) and the evolution of the crystallite size before and after sintering at high temperature. A study was conducted on the stability of the nanostructure of the sintered material. The effect of adding carbon on the structure and the crystallite size was studied for the sintered material. The X-ray diffraction technique was used to identify the new phases and measure the crystallite size as well as the microstrains induced by mechanical alloying. Scanning electron microscopy revealed structural changes in the milled and sintered materialItem Characterization of the interface of a Non-Ferrous dissimilar realized by rotary friction welding(Springer, 2021) Mebtouche, A.; Bezzazi, Boudjema; Ramou, N.; Aboudi, D.; Faci, Y.; Latef, M.The need for assembly between dissimilar materials often arises in complex industrial applications. It avoids problems inherent in conventional welding. Therefore, in this study the performance of welded joints developed using a rotary friction welding machine, between Cu/Al, are characterized. The interface of the welded assembly of dissimilar copper Cua1 and AA2014 aluminum, consists of several intermetallic compounds mainly CuAl2, CuAl and Cu9Al4. Dendrites have been revealed, this structure is known to be the result of solidification. While rotary friction welding is done at the solid state. In this work, we seek to know the phenomena that take place during the entire process and in the creation of the interface. This article presents the study of the Al/Cu interfacial structure of welded joints made by rotary friction in a modified cycle with two stepsItem Alkali treatment effect on physicochemical and tensile properties of date palm rachis fibers(Taylor & Francis, 2020) Bezazi, Abderrezak; Boumediri, Haithem; Garcia del Pino, Gilberto; Bezzazi, BoudjemaThis work aims to optimize the physicochemical and tensile properties of vascular fibers extracted from a local date palm rachis in Algeria. This fiber has a very specific composition and architecture and is different from the remaining fibers obtained from the six possible parts of the tree. For this purpose, a Taguchi orthogonal array design L16 was applied to reduce the number of experiments. The fibers were extracted from the rachis with two different methods (boiling and retting in water) and treated by NaOH with various concentrations (1%, 2%, 3%, and 5%) and for different durations (1, 4, 8, and 12 h). They were characterized using SEM-EDX, ATR-FTIR, XRD, and TGA to understand the effects of the extraction method and alkali treatment. A statistical treatment of the data was carried out based on the S/N ratio and ANOVA was performed to identify the most significant parameters affecting the tensile strength and the Young’s modulus of the fibers. A desirability function was developed to identify the optimal factors leading to the maximization of the tensile propertiesItem Composite Cross-Ply Laminates Stacking Sequence Effect on Post Flexural Fatigue Residual Strength(Springer link, 2021) Bezazi, Abderrezak; El Mahi, Abderrahim; Bezzazi, Boudjema; Del Pino, Gilberto Garcia; Scarpa, FabrizioThis paper concerns an experimental approach to the stacking sequence influence on cross-ply laminates behaviour. Effects of fatigue on the residual strength and stiffness are investigated through performing post fatigue static test after specific numbers of cycles. Residual strengths were measured by testing specimens to a certain number of cycles then static tests to rupture were performed after the specimen had been unloaded without being removed. The results obtained indicate that as well as there is a drop in the specimen’s stiffness, there is a drop in the strength of the laminate as the number of cycle increases. However, this is also accompanied by an increase in the displacement mainly at higher number of cycles. The hysteresis loops revealed that a significant decrease in the maximum fatigue load was occurring as the number of cycles increased. It is also noted that the slope of the hysteresis loops decreased with respect to the number of cycles. However, a less significant drop in the minimum fatigue load than the maximum fatigue one was also observedItem Flexural fatigue failure of concrete reinforced with smooth and mixing hooked-end steel fibers(Cogent, 2019) Saoudi, Nacira; Bezzazi, Boudjema�This paper presents an experimental study on flexural fatigue dynamic behavior of reinforced concrete. Steel fiber is used for the retrofitting and strengthening flexural members, by mixing short smooth steel fiber and hookedend fiber. By using Vibrophore HFP 150, dynamic loading was scanned at a resonance frequency of 100 Hz. Our objective is to examine the behavior of a specimen of 7 × 7 × 28 by a three-point bending test under high-level stress until it fails. Important research has been conducted to investigate the static and fatigue behavior of reinforcement. It was strengthened initially using one fiber, then using other additives. However, this research is not adequate to examine the flexural fatigue behavior of specimens by mixing different shaped fibers at different percentages. A further improvement in composite concrete performance is observed by mixing two steel fibers under high-level stress. The results are in alignment with the fatigue life data using Weibull distribution.
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