Browsing by Author "Bezzazi, B."

Now showing 1 - 20 of 29

Cross-ply laminates under static three-point bending : a numerical development model
(2012) Benbelaid, S.; Bezzazi, B.; Bezazi, A.
This paper considers damage development mechanisms in cross-ply laminates using an accurate numerical model. Under static three points bending, two modes of damage progression in cross-ply laminates are predominated: transverse cracking and delamination. However, this second mode of damage is not accounted in our numerical model. After a general review of experimental approaches of observed behavior of laminates, the focus is laid on predicting laminate behavior based on continuum damage mechanics. In this study, a continuum damage model based on ply failure criteria is presented, which is initially proposed by Ladevèze. To reveal the effect of different stacking sequence of the laminate; such as thickness and the interior or exterior disposition of the 0° and 90° oriented layers in the laminate, an equivalent damage accumulation which cover all ply failure mechanisms has been predicted. However, the solution algorithm using finite element analysis which implements progressive failure analysis is summarized. The results of the numerical computation have been justified by the previous published experimental observations of the authors
Dielectric behavior study of thermosetting matrices loaded
(2012) Irekti, Amar; Hami, B.; Aribi, Chouaib; Bezzazi, B.
The present study was prospective in nature and its purpose is twofold. It consists, on the one hand, to identify and characterize mineral fillers, secondly, to determine the dielectric properties of materials prepared using the epoxy resin mixed with local inorg anic fillers , very rich in silica such that: sandy, pozzolan, cullet and a small calcium carbonate amount. This application allows us to use the matrix developed as an electrical insulator. The results of our study show that the use of fillers further im proves the dielectric properties of these matrices. After 32 days of conditioning, the values of capacitance and resistance obtained are very remarkable. Comparing our results with previous work with the addition of pure silica, we note that our composites have better properties at a low cost. The hygro - thermal influence is much less important fo r the loaded resin. Our composites may be subject to external environmental influences and they have a range of wide usage in dielectric materials
The effect of carbon black on the curing and mechanical properties of natural rubber/ acrylonitrile- butadiene rubber composites
(Universidad Nacional Autonoma de Mexico, 2021) Boukfessa, Hind; Bezzazi, B.
The present work investigates the effect of the amount of carbon black on curing and mechanical properties such as tensile strength, elongation at break, hardness and abrasion resistance of the natural rubber (NR)/ acrylonitrile-butadiene rubber (NBR) blend. For that purpose, a blend composed of 65% NR and 35% NBR filled with different content of carbon black N330 was used. The curing results indicate that the viscosity and the crosslink density of rubber composites increase and the scorch and curing times decrease with increasing the filler content. Mechanical properties such as tensile modulus and hardness of the CB filled NR/NBR blend were remarkably improved, indicating the inherent reinforcing potential of CB. Regarding tensile strength and abrasion resistance, they increase with the addition of carbon black, up to 50 phr. After that, these properties decrease slightly with filler addition
Elaboration et caractérisation mécanique d’un matériau composite hybride
(2006) Hachemane, B.; Mir, A.; Bezzazi, B.
Etude Du Comportement Au Choc D’un Matériau Composite Renforcé Par Des Fibres De Verre
(Unité de Recherche Matériaux, Procédés et Environnement (URMPE), Université M'Hamed Bougara, Boumerdès.Cité Frantz Fanon, 35000 Boumerdès, Algérie, 2013) Hami, Brahim; Irekti, A.; Bezzazi, B.
Ce travail a pour objet d’étudier les caractéristiques mécaniques en flexion 3 points et en traction; en statique; et du comportement au choc de trois variantes de stratifiés constitués du mat et du tissé en fibres de verre et de résine polyester, dans le but de les utiliser dans la réparation des coques de bateaux et les valoriser dans l’industrie navale. Trois types de plaques stratifiés ont été élaborés par moulage au contact, Ces différentes variantes de stratifiés constitués defibre de verre tissé, mat et combiné (tissé et mat) ont été soumises à des essais mécaniques (traction et flexion 3 points). L’analyse des résultats des essais menés sur ces trois types de stratifiés montre qu’une variante sort du lot et donne des performances mécaniques plusélevées que les deux autres.
Experimental analysis of behavior and damage of sandwich composite materials in three-point bending. part 1. static tests and stiffness degradation at failure studies
(2007) Bezazi, A.; El Mahi, A.; Berthelot, J. M.; Bezzazi, B.
The analysis of stiffness and the identification of rupture mechanisms during and after static tests of sandwich panels and their components have been investigated. The sandwich panels, having cross-ply laminates skins made of glass fibre and epoxy resin were manufactured by vacuum moulding and subjected to three-point bending tests. Two polyvinyl chloride cores of similar type but with differing densities were investigated. The effect of core density and its thickness on the behavior and the damage was highlighted. In terms of stiffness and load at failure, the sandwich structure has better mechanical characteristics compared to its components
Experimental analysis of behavior and damage of sandwich composite materials in three-point bending. Part 2. Fatigue test results and damage mechanisms
(2009) Bezazi, A.; El Mahi, A.; Berthelot, J. M.; Bezzazi, B.
The analysis of stiffness degradation and the identification of damage mechanisms during and after fatigue tests of sandwich panels with PVC foam cores have been performed. The sandwich panels with cross-ply laminates skins made of glass fiber and epoxy resin were manufactured by vacuum moulding and subjected to three-point bending tests. Two PVC cores of similar type but with differing densities were investigated. The effect of core density and thickness on the damage behavior was highlighted. Using the cyclic life criterion, fatigue curves were plotted according to two models and compared with those of the literature. It has been demonstrated that the sandwich SD 2, with the higher core density, withstands a higher load and possesses greater rigidity in static tests, combined with an enhanced fatigue resistance, when compared to sandwich SD 1 which has a lower core density
Experimental study for the choice of a matrix epoxy resin for the elaboration of laminates
(2013) Aribi, C.; Bezzazi, B.; Mir, A.
The performances of composite materials are influenced by the properties of the matrix used. The latter ensures the desired form and the protection of the reinforcements against the external attacks. This work comprises a comparative study between laminates developed with different matrices in epoxy resin. Their characterization has to choose the best matrix able to give best results in static and dynamic tests. The resins used are provided by Granitex Algéria and which are primary Médapoxy STR resins, Médapoxy inject 812 and Médapoxy Al resin. Hence, the results of tensile tests prove a fragility of the AL resin which influences the maximal constraint of traction compared to the STR primary resin. Furthermore, Inject 812 resin shows very limited mechanical properties due to the changes of the epoxy network with the addition of diluents which has significantly decreased its viscosity
Experimental study of sandwich multilayer reinforced by glass fibre and agglomerated cork
(2014) Hami, Brahim; Irekti, Amar; Aribi, C.; Bezzazi, B.; Mir, A.
This paper presents an experimental study which is determined the mechanical properties of a composite material sandwich multilayer developed in the laboratory of mechanics of materials and composites, Materials Research Unit, process and en¬vironment. This type of sandwich is composed of four layers laminated based on an epoxy resin reinforced by woven glass fibres and mast between which three plates of agglomerated cork with stacked alternately laminated layers. Specimens for bending tests three and four points were prepared from the multilayer sandwich panels. A first series of static three-point bending tests shows a clear difference in the fracture behaviour for materials, laminate and cork. These materials have undergone a large plastic deformation without rupture achieve full sandwich, with the onset of delamination between layers laminated material and cork. In order to determine the bending stiffness modules D, the shear modulus and flexural N and the shear modulus of the soul Ga, we conducted a second test campaign four points bending. As a result, we can develop a variety of white cork produced in Algeria in order to use it in the construction and automotive industries
Fatigue behaviour of the laminates jute/epoxy
(2013) Mir, A.; Aribi, C.; Bezzazi, B.
Work presented is interested in the characterization of the quasistatic mechanical properties and in fatigue of a composite laminated in jute/epoxy. The natural fibres offer promising prospects thanks to their interesting specific properties, because of their low density, but also with their bio deterioration. Several scientific studies highlighted the good mechanical resistance of the vegetable fibre composites reinforced, even after several recycling. Because of the environmental standards which become increasingly severe, one attends the emergence of eco-materials at the base of natural fibres such as flax, bamboo, hemp, sisal, jute. The fatigue tests on elementary vegetable fibres show an increase of about 60% of the rigidity of elementary fibres of hemp subjected to cyclic loadings. In this study, the test-tubes manufactured by the method infusion have sequences of stacking of 0/90° and ± 45° for the shearing and tensile tests. The quasistatic tests reveal a variability of the mechanical properties of about 8%. The tensile fatigue tests were carried out for levels of constraints equivalent to half of the ultimate values of the composite. Once the fatigue tests carried out for well defined values of cycles, a series of static tests of traction type highlights the influence of the number of cycles on the quasi static mechanical behavior of the laminate jute/epoxy
Flexural fatigue behavior of cross-ply laminates.An experimental approach
(2003) Bezazi, A.; El-Mahi, A.; Berthelot, J. M.; Bezzazi, B.
Within an experimental approach we describe the mechanical behavior of different resin-epoxy laminates reinforced with cross-ply Kevlar and glass fibers under conditions of static and cyclic three-point bending. In static tests, we consider the effect of stacking sequence, the thickness of 90°-oriented layers, reinforcement type on the mechanical behavior of laminates under loading and on realization of various damage modes leading to rupture. Cyclic loading studies have been performed in two steps. In the first stage, we inquire into the dependence of the behavior and durability of four glass fiber-reinforced laminate-types on the stacking sequence; the second stage is devoted to studying the dependence of cyclic strength and fatigue behavior of laminates on the reinforcement type. Fatigue tests are carried out in load-control regime for glass and hybrid (Kevlar + glass) fiber laminates. Fatigue curves are constructed in coordinates “stress – number of cycles until fracture” from the criteria corresponding to a drop in stiffness by 5 and 10%. Analysis of the results obtained permits evaluation of the effect of the stacking sequence and the reinforcement type on the behavior of cross-ply laminates in cyclic loading. The presence of Kevlar fibers accounts for nonlinear behavior of laminates in static tests and for low cyclic strength in fatigue tests under three-point bending
Inspection of laminated composite materials by two ultrasonic techniques
(University of M’HAMED Bougara Boumerdes, 2013) Halimi, Rafik; Bezzazi, B.; Badidibouda, A.; Aribi, C.; Satour, A.
This paper presents some ultrasonic methods to detect and to characterize defects, possibly obtained after damage caused in composite materials. Firstly, artificial defects are located by two piezoelectric transducers. A two-dimensional ultrasonic cartography C-scan, performed section by section, at different positions which took part through the thickness of a carbon fiber-reinforced plastic composite beam, to be analyzed. Next, fundamental symmetric S0 mode of Lamb waves is used to measure the size of the delamination by scanning over the surface beneath which a delamination lies. A remarkable decrease in the arrival time due to the delamination is detected, and the delamination length can be calculated based on a simple model for Lamb-wave propagation. Furthermore, the delamination edge is located as a sudden decrease in the amplitude. The rate of decrease in amplitude of an individual pulse cycle was detected to vary with the depth of the delamination, being most sensitive to delaminations near the surface of the plate. This is particularly useful when sizing for defects close to the surface, where a normal-incidence pulse-echo ultrasonic method has problems, particularly when the depth of the defect or the back-wall echoes lie within the length of the transmitted ultrasonic pulse. The technique has potential for faster c-scanning of a complete plate than the usual normal-incidence pulse-echo method
Materials and sustainable development CIMDD 2013 Boumerdes, may06 th to 09 th , 2013
(2013) Bezzazi, B.
Mechanical and damage properties of polyethylene reinforced with clay treatment
(Technology Publishing Group, 2021) Chebbab, Brahim; Djeziri, M.; Bezzazi, B.
This document is the subject of an experimental study for composite material implementation with a polyethylene matrix (HDPE) embedded with clay particles. We carried out a chemical optimization applied to clay particles by characterizing the mechanical behavior as well as the damage of the elaborated composite material. The work is based on the following optimized procedure: a mixture of sodium thiosulfate (Na2S2O3) and clay cooled and centrifuged for 15 minutes. The clay pellet is rinsed twice with 0.05 M HCl for 3 to 4 hours. The mechanical properties of the composite material obtained are relative to the mass fraction of treated and untreated clay. The Young's modulus is found to change as the mass loadings of the injected treated clay change, with a marked improvement over virgin HDPE from 1590.90 to 1667.32 MPa, the yield strength from 28.68 to 31.73 MPa, and the ultimate tensile strength from 19.99 to 20.84 MPa. This positive variation is achieved at a maximum of 7% mass load of treated clay. Beyond this rate, the composite material experiences a drop in these same parameters due to the high concentration of clay. Scanning electron microscopy is used to see differences in dense microstructure between specimen granules
Modeling damage of the hydrogen enhanced localized plasticity in stress corrosion cracking
(2010) Benbelaid, S.; Belouchrani, M. A.; Assoul, Y.; Bezzazi, B.
Stress corrosion cracking is an important and complex mode of failure in high-performance structural metals operating in deleterious environments, due to metallurgical, mechanical, and electrochemical factors. Depending on the material/solution system, the stress corrosion cracking mechanism may involve a combination of hydrogen embrittlement (HE) and anodic dissolution. In this article, a numerical model for predicting the mechanical behavior of hydrogen-induced damage in stress corrosion cracking is described. The methodology of modeling used in this study is based on the thermodynamics of continuum solids and elastoplastic damage. This model is based on a stress corrosion mechanism that occurs through the simultaneous interaction of hydrogen and plasticity. This mechanism is also called hydrogen-enhanced localized plasticity, which is a viable mechanism for hydrogen embrittlement. The model is applied to the fatigue damage problems of nuclear reactor pipe, and the results are compared with published fatigue life data obtained experimentally
Modelling damage of composite laminates with different stacking sequences
(2013) Benbelaid, S.; Bezzazi, B.; Bezazi, A.
Multilayer system of thermosetting polymers and specific confining : application to the walls of the hospital unit
(Photon Excellence Award-2014 : The Journal of Materials Science, 2014) Bouzid, Mohammed; Djadi, A.; Aribi, C.; Irekti, Amar; Bezzazi, B.; Halouene, F.
The nature of materials structuring our health institutions promote the development of germs. The sustainability of nosocomial infections remains significant (12% and 15%). One of the major factors being the portland cement which is brittle and porous. As part of a national plan to fight nosocomial infections, led by the University Hospital of Blida, we opted for a composite coating, application by multilayer model, composed of epoxy-polyester resin as a binder and calcium carbonate as mineral fillers. The application of composite materials reinforce the wall coating of hospital units and eliminates the hospital infectious areas. The resistance to impact, chemicals, raising temperature and to a biologically active environment, gives satisfactory results
Quasi-static mechanical characterization and fatigue of a composite laminates
(2014) Belkacemi, C.; Bezzazi, B.
This present work focuses on the quasi- static mechanical characterization and or fatigue of a composite materials (laminate) jute/polyester manufactured under vacuum and with stacking sequences of 0/ 90. The obtained results of tensile tests on the laminate, showed a similar behavior on two levels: a linear portion up to 20 MPa and a nonlinear portion to rupture at 47 MPa σ max , followed by elongation of 2.08 % with a break elongation up to 2.50 %. Also, it was noted that increasing the temperature of the samples (5-6 ° C ) when the fatigue test remains in ISO 13003 , which requires a temperature increase of less than 10 ° C. the results of fatigue test showed also that with a loading of 50% of the maximum load reached more than one million cycle, the more load is increasing the cycle numbers of decreases
Rheological behavior of the epoxy resin loaded with the pozzolan
(2012) Irekti, Amar; Hami, Brahim; Aribi, C.; Bezzazi, B.; Briki, I.
The study is to synthesize composite materials with news formul ations of thermosetting matrices by the incorporation of 40% of mineral fillers to reduce the cost of composite materials an d to improve implementation by increasing the viscosity and redu cing the withdrawal to its minimum value. The mineral filler increases si gnificantly in rheological parameters, whatever it nature of th e mineral filler. Compared to the control without charges, an increase of 60% of the shear stress and that of plastic viscosity were reco rded for the epoxy resin. The software Rheowine viscometer enabled us to m odel and identified the rheological behavior of these mixtures wit h resin. The results obtained in this modeling, confirmed that th e resin mixtures have shear-thinn ing rheological behavior, this last allows the model of the Ostwald de Waele
Rheological study of composite materials based on thermosetting matrix and fillers mineral
(2013) Irekti, Amar; Bezzazi, B.
In the development of composites materials, the matrix acts as a binder of different reinforcements can distribute the stress, provide good resistance to chemical structure and the desired shape to the final product. But there are still some drawbacks that arise in the physicochemical and mechanical properties of thermosetting matrices. Our job is to synthesize composite materials with news formulations of thermosetting matrices (Granitex products) by the incorporation of 40% of local mineral fillers. The latter give the matrix properties which it does not have, first, to reduce the cost of composite materials, and secondly, to improve implementation by increasing the viscosity and reducing the withdrawal to its minimum value. Rheological testing of mixtures prepared is made on the cone-plate viscometer, or the sample undergoes a shear in the conical space between the plane and the cone. The geometry of the cone - package ensures constant velocity gradient throughout the volume. The rheograms obtained, represents the evolution of the shear stress as a function of shear rate of resin mixtures containing 35% of mineral filler (pozzolan). The mineral filler increases significantly in rheological parameters, whatever the nature of the mineral filler. Compared to the control without charges, an increase of 60% of the shear stress and that of plastic viscosity were recorded for the epoxy resin. The software Rheowine viscometer, enabled us to model and identified the rheological behavior of these mixed with resin. The results obtained in this modeling, confirmed that the resin mixtures have shear-thinning rheological behavior and their behavior follows the model of the Ostwald of Waele