Browsing by Author "Dilmi, Hamid"

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    Effect of Alternating Hybridisation of Fibres on the Physico - Mechanical Behaviour of Composite Materials
    (Sciendo, 2023) Harb, Noura; Dilmi, Hamid; Bezzazi, Boudjema; Hamitouche, Kahina
    The 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.
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    The fatigue flexural behavior of fiber reinforced concrete : effect of the parameters of coarse aggregates
    (Academic Journals, 2015) Dilmi, Hamid; Aribi, C.; Safi, Brahim; Bezzazi, Boudjema; Saidi, M.
    The effect of the coarse aggregate type on the fatigue flexural behavior of concrete was investigated in this work. Three types of the coarse aggregates were selected from three different careers (CA1, CA2 and CA3). The mechanical parameters of these aggregates were determined (Los Anglos and Micro Deval). Prismatic specimens (70×70×280 mm) for each concrete mixture were made with aggregates of each source. The flexural fatigue tests were conducted on these concrete samples with varying levels of loading of 55 to 80% and the ultimate flexural strength. The test frequency is around 80 Hz and it is automatically determined by pulsing the fatigue machine for a resonance situation (the phase shift is δ=0) between the mass-spring-specimen system. The obtained results show that the aggregates which have the similar parameters (Micro Deval and LA), provide better adhesion with cement paste, and therefore a greater bending strength. The strength evolution at short-term age is typical for specimens based on aggregates with low wear resistance by triturate (a high Micro Deval coefficient). Regarding the fatigue flexural behavior, the concrete specimens based on CA1, which have similar coefficients of Los Angeles and Micro Deval (respectively 18 and 16) present the behavior (load/cycle numbers) close to that of the model prototype of the Wöhler curve. This can be explained by a high homogeneity of the charge distribution during fatigue test compared to other concrete mixtures. Also, it was noted that the relationship between the endurance limit and the coefficient of Los Angeles is inversely proportional: The aggregates which have good strength to fragmentation (low coefficient of LA), as aggregates CA2 case give an endurance limit at around 70% max bending load
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    FTIR analysis and rheological behavior of bisphenol : a diglycidyl ether resin filled Fume-Silica
    (2014) Irekti, Amar; Bezzazi, Boudjema; Boualam, Chahrazed; Aribi, Chouaib; Dilmi, Hamid
    Silica-fume as fillers into polymers materials affect significantly the physical, mechanical and the electrical properties of the polymers. The polymer that we studied here is an epoxy based resin (STR) and silica fume (FS). This paper presents the dependency of the rheological behavior of the STR epoxy resin on the FS content within a temperature at which the reaction thermoset is neglected. We used a cone-plate viscometer for the study of the rheological behavior, and a scanning electron microscope is used for the analysis of the dispersion state of the FS in STR epoxy resin. Compared to the control without loads, an increase of 50% of the shear stress and the plastic viscosity were recorded for the composite. The software Rheowine viscometer enabled us to model and identified the rheological behavior of these mixtures with resin. The results obtained in this modeling, confirmed that the resin mixtures have shear-thinning rheological behavior, this last give us the model of Ostwald de Waele