http://arthra.ugal.ro/handle/20.500.14043/25802 2026-04-16T20:35:26Z http://arthra.ugal.ro/handle/20.500.14043/25818 The Unusual Electomagnetic Proprieties of Fabric Reinforced Epoxy Composites Bunea, Marina; Bria, V.; Cîrciumaru, A.; Bîrsan, I. G. In this research, the electromagnetic behavior of four composite materials was investigated as an important issue of composite researchers is to control the electrical properties of polymer matrix composites. The four materials are epoxy matrix fabric reinforced composites. Each of the reinforcements is accomplished from 17 layers of fibers fabric of each type, excepting the medial layer which is made of a hybrid fabric meant to solve two issues – the first issue refers to gathering information about the materials loading state while the latter is to increase the electromagnetic shielding properties of the formed materials. The four used fabrics are simple plain fabrics made of yarns of carbon fibers, aramid fibers and, respectively, two types of glass fibers. All the reinforcement layers, excepting the medial one, have the yarns of warp and fill, respectively parallel, while the medial layer has warp yarns perpendicular on the warp yarns of the other layers. The matrix of the wet lay-up technique formed materials is made of epoxy system Epiphen RE 4020 – DE 4020. The Annals of "Dunarea de Jos" University of Galati Fascicle IX Metallurgy and Materials Science No. 2 - 2015, ISSN 1453 – 083X 2015-01-01T00:00:00Z http://arthra.ugal.ro/handle/20.500.14043/25817 Compressive Behaviour of ultra-Sonicated Starch / Carbon Black / Epoxy Composites Graur, Iulia; Mihu, Georgel; Bria, Vasile; Cîrciumaru, Adrian; Bîrsan, Iulian Fillers are generally used in order to change some basic properties of polymer matrix but the filler particles often tend to aggregate with consequences in terms of the mechanical properties of the final composite. In order to avoid aggregation, many solutions have been proposed and one of them is to use ultrasounds in various stages of composites formation. In this study, the compressive behaviour of filled epoxy was analysed. As filler, at a 10% volume ratio, a mixture of three parts of starch and one part carbon black was used. The aim of the analysis was to identify the effect of ultra-sonication at different frequencies and for different periods of time on the compressive properties of composites. The Annals of "Dunarea de Jos" University of Galati Fascicle IX Metallurgy and Materials Science No. 2 - 2015, ISSN 1453 – 083X 2015-01-01T00:00:00Z http://arthra.ugal.ro/handle/20.500.14043/25816 Strength Analysis of a Composite Joint Used in Ship Structure Rotaru, Florentina; Chirică, Ionel; Beznea, Elena Felicia Low weight and high strength panels are always taken into account when designing materials for sandwich panel technology, which offers an efficient solution for different problems. Different types of sandwich panels are currently being used depending on the applications. Honeycomb sandwich panels are a better solution in structural design problem. The work presented in the paper is focused on the study of the behaviour of a composite joint used in ship structure, loaded by transversal force. The components of the joint are sandwich plates, made out of core polypropylene honeycomb and extruded polystyrene and face sheets of the resin polymer. A typical sandwich panel is made of three layers, in which two thin sheets (faces) of a stiff and strong material are separated by a thick core of lowdensity materials (Allen, 1961). Considering the various uses of these materials in numerous fields, it is essential to know their mechanical properties so as to predict and calculate their behaviour in specific and diverse environments. The Annals of "Dunarea de Jos" University of Galati Fascicle IX Metallurgy and Materials Science No. 2 - 2015, ISSN 1453 – 083X 2015-01-01T00:00:00Z http://arthra.ugal.ro/handle/20.500.14043/25815 Water-in-Diesel Emulsions as an Alternative Fuel for Diesel Engines. Part II: Performance of Diesel Engines Fueled with Water-in-Diesel Emulsions. A Literature Review Vrabie, Vlad; Scarpete, Dan; Chiosa, Bianca Elena This paper presents the recent advances of water-in-diesel emulsion fuel studies, especially the impact of using this emulsion fuel to the performance and emissions of diesel engine. Studies revealed that the onset and the strength of micro-explosion process give strong effect with regard to the combustion efficiency inside the combustion chamber. Most of the researchers tested emulsions with water content of 5-40% in diesel fuel. Some studies concluded that 20% water in the emulsion fuel gives the optimum engine performance. Many researchers and experts agree that the reason why there is a slight drop in brake power and torque is the fact that water-in-diesel emulsion fuel has a lower heating value than a neat diesel fuel, thus less energy is released during combustion. In general, the results suggest that the water emulsification has a potential to slightly improve the brake efficiency and to significantly reduce the formation of NOx, soot, hydrocarbons and PM in the diesel engine. Some factors may affect the experimental results that need to be considered, such as the effect of volatility of the base fuel, the water content of the emulsion, emulsion stability, ambient temperature, pressure, type of surfactant and engine test conditions: engine load, speed, injection timing and compression ratio. The Annals of "Dunarea de Jos" University of Galati Fascicle IX Metallurgy and Materials Science No. 2 - 2015, ISSN 1453 – 083X 2015-01-01T00:00:00Z