Publications Internationales

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Author: search.filters.author.Safi, BrahimHas files: No

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    Experimental and numerical investigation of impact behavior in honeycomb sandwich composites
    (SAGE, 2024) Djellab, Amira; Chellil, Ahmed; Lecheb, Samir; Safi, Brahim; Mechakra, Hamza; Houari, Amin; Kebir, Hocine; Madani, Kouider
    This paper presents an experimental and numerical study on the low-energy impact fatigue and bending behavior of sandwich panels reinforced with composite laminate glass and carbon fabric facesheets, supported by a honeycomb core made of Nomex. The crushing behavior of honeycomb sandwich specimens subjected to the impact test was compared and discussed. Our results indicate that the carbon composite facesheets have a significant effect on the impact, resulting in an increase in impact resistance and a 157.14% increase in crack depth in the elastic region compared to glass facesheets reinforcement. This increase serves as an indicator of the laminate's ability to resist damage initiation and impact fracture mechanisms. Also, an increasing in flexural strength about 45.72% was observed in carbon facesheets honeycomb specimens compared to glass facesheets reinforcement. Microscopic illustration of the damaged honeycomb sandwich specimens was conducted to evaluate the interfacial characteristics and describe the damage mechanics of the composite facesheets and core adhesion under the impact test. The numerical approach proves to be efficient in terms of accuracy and simplicity compared to existing methods for predicting the damage mechanisms of honeycomb sandwich structures. It was noted that results of numerical study show best agreements with experiment results and the model can be used to predict the low-energy impact fatigue.
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    Rheological and Physic-mechanical study of metallurgical cements based on Nano-silica combined with blast furnace slag
    (Matrix Rom, 2020) Bouali, Khaled; Daoui, Hakim Mohammed; Safi, Brahim
    Această lucrare tratează comportamentul reologic și mecanic al cimenturilor metalurgice bazate pe nano-silice (NS) combinate cu zgură de furnal (GBFS). Un studiu experimental a fost realizat cu un raport constant de apă / liant (A / L) de 0,5 utilizat pentru toate mortarele studiate. Pentru a utiliza maximul GBFS și a scădea consumul de ciment, diferitele conținuturi (36% și 66% .wt) GBFS și 3% .wt de NS au fost alese și adăugate la Portland Cement (PC). Au fost efectuate teste reologice pe paste cimentate și au fost efectuate teste mecanice pe mortare elaborate cu ciment metalurgic studiat. Rezultatele obținute arată că pastele de ciment cu 3% NS fără GBFS au fost cele mai puțin vâscoase și au un efort de forfecare mai scăzut, cu o workabilitate acceptabilă în comparație cu alte paste de ciment. Cu toate acestea, în prezența GBFS, pastele de ciment devin mai vâscoase, ceea ce face ca debitul să fie mai dificil, cu o forță de forfecare mai mare la debit. De asemenea, rezultatele au arătat, în comparație cu mortarele de control GBFS, că încorporarea unei mici cantități de NS în ciment în prezența GBFS crește în mod remarcabil rezistența la compresiune la 28 și 90 de zile. Incorporarea a 3% în greutate NS în pastele de ciment cu un conținut de GBFS de 36% și 66% în greutate a dat valori ale rezistenței la compresie de foarte mare 90 zile (71,70 și 56,30 MPa). NS și LHF pot reduce în mod remarcabil porozitatea matricei de ciment și cresc densitatea acestuia, ceea ce explică de asemenea rezistența ridicată la rezistența la compresiune.
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    Highlighting of the distribution effect of steel hook fibers at low and high dosage on the flexural strength of self-compacting mortars
    (2022) Kheddache, Lynda; Aribi, Chouaib; Chahour, Kahina; Safi, Brahim
    In this paper, the distribution effect of low and high dosage steel hooked fibers on the flexural strength and mechanical behaviour of self-compacting mortars is investigated. Specimens were shaped so as to distribute the steel hooked fibers in three layers at different dosage (volume fraction of 0.25%, 0.40% and 0.50% respectively for each layer). The obtained results show that the mechanical behaviour in flexural and the flexural strength of the reinforced self-consolidating mortars were significantly influenced and directly depending on the fibers distribution per layer. This finding clearly shows the importance of the steel fibers distribution in the cement matrix during implementation has a major influence on the mechanical behaviour of mortars reinforced with metal fibers. The maximum value recorded is 14.5 MPa for the high dosage. The distribution of the steel fibers by layer made it possible to obtain a strength gain of 71.83% at low dosage and more than 100% at high dosage
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    Study of the behaviour of mortars based of cements composed toward the attacks of acids waters
    (2011) Driss, Miloud; Hamadouche, Mohamed Amine; Kerbouche, Abdelkader; Oumrani, Nasereddine; Safi, Brahim
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    Optimization of the process of cooking and drying of brick
    (isjaee, 2010) Saidi, Mohammed; Hamiane, Messaoud; Benmounah, A.; Safi, Brahim
    The construction materials play an enormous part in the economy of the country; this industry comprises a very varied range of products going of simple pottery passing by brick of construction until the technical porcelain and the industry of cements. As, this production takes a so important rise as the realization of manufacturing plant becomes a daily reality. This realization of quite quantitative factory that qualitative depends on the availability of a raw material of quality, means of production in good knowledge and operating condition to make allowing a perfect control of the process. Considering, the enormous part which plays the construction materials in particular the bricks of construction in the economy of the country. We were interested to make a study concerning the production unit of bricks of Boudouaou (east of Algeria) on the technological, thermal and economic level since the essential study is made on the thermal part in order to calculate the acceptable mode of cooking and to calculate the combustion of gas. The study of the heat balance enables us to know how calculations can be carried out and of knowing how and the energies brought to the furnace spent are consumed. This study enabled us to make a saving in gas in the order of 63.5 m³/h and to make a profit of energy of 266.37 kJ/kg of product and to obtain a better use of the drier and furnace with a possible maximum thermal efficiency
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    Ostwald Ripening Phenomena in B2O3-PbO Glass System
    (2009) Aboutaleb, Djamila; Iratni, Aicha; Safi, Brahim
    Lead borate glass was prepared by the quench method, followed by treatment at its isothermal temperature at different time periods. When the sample was rapidly cooled from the melt, it showed two distinguished opalescent layers. The SEM analysis and XRD pattern provide characteristics of glass without XRD peaks and their morphology show the aggregated spherical particles in the phase separated glass. This data show that phase separation occurred even when the melts were rapidly cooled. However, the sample shows a Ostwald ripen with increasing time of heat treatment, which implies that the size of particles increases and their number decreases. The infrared absorption spectra show shift edge for sample glass with heat treatment, which indicates a change of structural configuration, i.e. conversion of tetrahedral boron on triangular boron coordination
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    Mechanical behavior and chemical durability of marble-based mortar: Application to panels subjected to punching
    (Elsevier, 2019) Chahour, Kahina; Safi, Brahim
    The main purpose of this paper is to use marble as sand in the mortar composition and to study the impact of natural sand replacement on mortar properties, such as mechanical strength, rheology and durability of different mortar mixtures at different curing ages up to 56 days. Natural sand (NS) was substituted by marble sand at different percentages (0%, 30%, 50%, 70% and 100% by weight of NS). The fresh property (workability), hardened properties (compressive, flexural and punching strength), compactness (ultrasonic wave speed) and durability (acid and water resistance) of the mortars studied were evaluated. A complementary study on mechanical behavior of panels elaborated with the studied mortars has been conducted; the test results have shown that mortar with 50% and 100% of substitution rate give better results for compactness, compressive and flexural strength. The punching strength obtained by the punching shear test has been significantly improved by the increase of natural sand substitution rate. However, panels carried out marble-based mortars with 70% of marble sand have given a punching strength similar to that obtained by control mortar panel (100% natural sand). This result has been also proven by the improvement of the mechanical behavior of slab made with 100% marble mortar. Results of durability estimated by acid attack have shown that loss in weight of mortar mixtures decreases with the increase of the percentage marble sand. Whereas, beyond 50% of marble sand content, water permeability increases compared to that of mortar control
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    Effet du dosage et de la repartition des fibres Metalliques sur le comportement mecanique en flexion Des mortiers autoplacants fibres
    (2019) Kheddache, Lynda; Chahour, Kahina; Safi, Brahim
    Ce travail décrit l'influence du dosage et la répartition des fibres métalliques sur le comportement en traction par flexion des mortiers autoplaçants fibrés. Des essais de flexion trois points ont été réalisés sur des éprouvettes prismatiques de dimensions 40x40x160 mm à l'âge de 28 jours, en faisant varier la quantité (20, 30 et 40 kg/m3) et la répartition des fibres métalliques. Les résultats obtenus ont montré que la résistance à la traction par flexion est d'autant plus importante que le dosage en fibres est important. Par ailleurs, l'effet de la répartition des fibres a été mis en évidence, puisque un gain de la résistance allant jusqu'à 50 % a été obtenu, comparé au mortier autoplaçant sans fibres
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    Comparative Life Cycle Assessment of Two Types of Truck Bumper Produced in the Algerian Auto Industry
    (Bio One, 2020) Kebbouche, Zahia; Tairi, Abdelaziz; Safi, Brahim
    Currently, the reduction of weight in automotive is a very important topic to reduce the air pollution. In this context, the purpose of the present paper is to analyze a real case study through a comparison of the environmental impacts between a conventional steel bumper and a polyester prototype. In the first part of this work, a door-to-door life-cycle assessment methodology was used throughout the study of the component manufacturing phase. The SIMAPRO7.0 software is used to evaluate the impacts of both bumpers on the environment and health. The second part is devoted to dust analysis from the polyester workshop. The obtained results have allowed us to show the company that its choice of steel substitution by the polyester is advantageous for certain impacts including the impact of climate change, but unfortunately there may be, given the working conditions of the polyester workshop, a transfer of impact, since we will end up with a risk of health (irritations, cancers) for the workers. LCA has proven to be a very useful tool for validating a redesigned automotive component from an environmental point of view; from this case study, several recommendations were made for the company to design environmentally friendly components , and ecodesign should be introduced into the company's procedures