Прегледај по Аутор "Đurić, Aleksija"
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- СтавкаAnalysis of the wind effect on the mechanical structures in the case of the four-side sunshade(2019) Marković, Biljana; Krajišnik, Milija; Đurić, AleksijaThis paper presents the analysis of the wind effect of four-side sunshade construction. The aim of the paper is to demonstrate the possibility of applying analogy in research, with examples from civil constructions, in order to simplify and reduce the analysis. The paper presents the analytical calculation of the pressure on the sides of the four-sided sunshade, analogously to the calculation of pressure on the four-sided roofs of civil construction objects.
- СтавкаCALCULATION OF LBKz FACTOR FOR CARBON FIBER REINFORCED POLYMER UNDER COMPRESSION AND THEIR COMPARISON WITH OTHER LIGHTWEIGHT MATERIALS(University Politehnica Timisoara, Faculty of Engineering Hunedoara, 2018) Đurić, Aleksija; Marković, BiljanaThe aim of this paper is to show which material, based on the LBKz factor, is more applicable in lightweight constructions. The LBKz factor has been calculated for three different groups of material (CFRP, hybrid laminates and materials applicable in additive technologies), and the calculation was based on the results obtained from our own experimental testing, as well as from the research results shown in available papers of other authors. The experimental compression testing was performed on the CFRP material.
- СтавкаCALCULATION OF THE MAIN ENERGY CHARACTERISTICS OF PLANT STEAM TURBINES WORKING ON THE CLAUSIUSRANKINE CYCLE WITH REHEATING(University Politehnica Timisoara, Faculty of Engineering Hunedoara, 2016) Vučinić, Radivojka; Srđan, Pelkic; Krstova, Keti; Đurić, AleksijaThrough this work is shown the calculation procedure for the main energy characteristics of plant steam turbines working on the Clausius-Rankine cycle with reheating. The parameters that we are going to analyze are the level of usefulness ηPPT, specific heat consumption qPPT, total and specific steam consumption MTVPu, mPPT and the unit useful work LiTeq . This project was developed for maximum continuous power turbines of 235 MW, all the other parameters that were used in the calculation are listed in the the work. The aim of this research is to show the comprehensive budget mentioned turbines and making the schematic operation of the system with calculated characteristics, which could be used as a good basis for the design of thermal power plants.
- СтавкаDEVELOPMENT OF NEW PRODUCTS IN INDUSTRY OF UPHOLSTERD FURNITURE(University Politehnica Timisoara, Faculty of Engineering Hunedoara, 2015) Pelkić, Srđan; Đurić, Aleksija; Marković, Biljana; Vučinić, RadivojkaThis paper presents the development phases of new products in the upholstered furniture industry, ranging from market research to mass production. During the development of the new products, teams od experts from various fields are included, such as: mechanical engineering, chemistry, architecture, economics, which has been discussed in this paper. Also, for preparation of this paper has been used CAD/CAM technology, without which is unthinkable to develop new products today. The emphasis, during the development of new product, is put on flexibility of product, price, quick and simple installation, improvement of productivity, materials, environmental standards and specifications, transport and packaging, marking and identification of products in stock, technical documentation, making the zero batch and, at the end, batch production, i.e. at all stages and elements essentials for the development of new products, which target is competitiveness in the market of upholstered furniture.
- СтавкаDISSIMILAR WELDING OF ALUMINUM ALLOYS 2024 T351 AND 6082 T6 BY TIG PROCESS(Sveučilište u Slavonskom Brodu, Strojarski fakultet, Društvo za tehniku zavarivanja Slavonski Brod, 2023) Milčić, Dragan; Milčić, Miodrag; Vuherer, Tomaž; Đurić, Aleksija; Mitić, Dragan; Radovanović, AndrejaThe aim of this work is to study the metallurgical and mechanical properties of dissimilar assemblies of 2024 T351 and 6082 T6 aluminum alloy by the TIG process. Aluminum alloy 6082 T6 is well weldable by classical fusion welding processes (MIG and TIG), while aluminum alloy 2024-T351 is almost non-weldable. Base metals were sheets with a thickness of 8 mm. The assembly of the plates was carried out by filler wire of an aluminum alloy type 4043A (AlSi5) with 2 mm of diameter. For the welding of these two Al alloys by TIG welding process in argon a shielding gas. The microstructural evolution across the welded joint dissimilar AA6082-T6 to AA2024-T351 aluminum alloy was characterized using optical and scanning electron microscopy (SEM). The hardness welded joint is the smallest in the melted area and the biggest on the side of 2024 alloy in HAZ. The fracture surface section of the tensile specimen is in the HAZ zone on the BM side - 6082-T6. The tensile strength of the welded joint is 166 MPa compared to 310 MPa for alloy 6082-T6 which is a weaker welded joint material, i.e. the reduction is about two times.
- СтавкаEXPERIMENTAL DETERMINATION OF SLIDING BEARING OPERATING TEMPERATURE(University Politehnica Timisoara, Faculty of Engineering Hunedoara, 2016) Vučetić, Nikola; Đurić, Aleksija; Milutinović, MiroslavDuring operation, it is essential to know theoperating temperature of the bearing in order to determine the thermal stability of the sliding bearing. This paper presents results of measuring the operating temperature of the sliding bearing using FLIR camera, on the testing table in the Laboratory of Applied Mechanics and Mechatronics, in Mechanical Engineering Faculty in East Sarajevo. Experimental results are presented ona diagram, followed by their comparison with the values ofthe operating temperature obtained analytically. Based on the operating temperature obtained through experiments and analytical calculation, thermal stability of the sliding bearing hasbeen tested.
- СтавкаEXPERIMENTAL MEASUREMENT OF SLIDING BEARING TEMPERATURE USING THERMOGRAPHY(Faculty of Engineering Hunedoara, University Politehnica Timisoara, 2019) Moljević, Slaviša; Đurić, Aleksija; Gojković, Ranka; Marković, BiljanaIn this paper is shown an example of the use of thermography in the measurement of temperature of the sliding bearings. The temperature is very important by sliding bearings, so it is necessary to measure frequently and the contactless gauges allow it in a very simple way. This paper shows that the measurement is bit dependent on the manufacturer of the camera that measures the temperature, it is important that the camera is intended for such measurements and that the basic parameters such as emissivity and measurement distance are well adjusted. Different camera manufacturers enrich accessories, which certainly helps users to handle the camera more easily, but from the aspect of temperature accuracy, cameras of the same characteristics give approximately similar results.
- СтавкаGEAR FAILURES EMBEDDED IN MANUAL GEARBOXES(University Politehnica Timisoara, Faculty of Engineering Hunedoara, 2016) Milutinović, Miroslav; Trifković, Spasoje; Đurić, Aleksija; Vučetić, NikolaDuring exploitation motor vehicle gearboxes are exposed to varying conditions. The changes are stochastic and dependent on many factors. These changes directly affect also to the gearboxes damage, and therefore the gears damage. Different types of damage can occur on gears, so that this paper will give focus on the damage on gears. According to DIN 3979 over 20 types of damage appearing on gear are given, while in this paper only damages on gears that are in gearboxes embedded will be presented. The paper contains the results of the damage percentage of manual gearboxes and the results of cumulative damage of manual six-speed gearboxes.
- СтавкаInfluence of Welding Speed on Fracture Toughness of Friction StirWelded AA2024-T351 Joints(MDPI, 2021) Milčić, Miodrag; Miličić, Dragan; Vuherer, Tomaž; Radović, Ljubica; Radisavljević, Igor; Đurić, AleksijaIn order to ensure a quality welded joint, and thus safe operation and high reliability of the welded part or structure achieved by friction stir welding, it is necessary to select the optimal welding parameters. The parameters of friction stir welding significantly affect the structure of the welded joint, and thus the mechanical properties of the welded joint. Investigation of the influence of friction stir welding parameters was performed on 6-mm thick plates of aluminum alloy AA2024 T351. The quality of the welded joint is predominantly influenced by the tool rotation speed n and the welding speed v. In this research, constant tool rotation speed was adopted n = 750 rpm, and the welding speed was varied (v = 73, 116 and 150 mm/min). By the visual method and radiographic examination, imperfections of the face and roots of the welded specimens were not found. This paper presents the performed experimental tests of the macro and microstructure of welded joints, followed by tests of micro hardness and fracture behavior of Friction StirWelded AA2024-T351 joints. It can be concluded that the welding speed of v = 116 mm/min is favorable with regard to the fracture behavior of the analysed FSW-joint.
- СтавкаKARAKTERIZACIJA ZAVARENIH SPOJEVA SA DELIMIČNOM PENETRACIJOM NA KONSTRUKCIONOM ČELIKU S355N(DUZS - Društvo za unapređivanje zavarivanja u Srbiji, Beograd, 2021) Milčić, Dragan; Mitić, Dragan; Radović, Nenad; Milčić, Miodrag; Đurić, Aleksija; Antić, MilicaPostojeći standardi zahtevaju zavarene spojeve sa potpunom penetracijom. Smatra se, da se zavarenim spojevima sa potpunom penetracijom, minimizira koncentracija napona u korenskom prolazu. Međutim, brojne su situacije u industriji, u kojima je zadovoljavajuća nosivost zavarenog spoja sa delimičnom penetracijom. Ako ispitivanja zavarenih spojeva sa delimičnom penetracijom pokažu zadovoljavajuću nosivost, benefiti u odnosu na zavarene spojeve sa potpunom penetracijom se ogledaju u nižim troškovima, odnosno manje je potrebno vreme za pripremu spoja, manje je potrebno dodatnog materijala, odnosno kraće je vreme neophodno za izradu zavarenog spoja. U radu je dato ispitivanje sučeonih zavarivanih spojeva konstrukcionog čelika S355N, sa delimičnom penetracijom, ostvarenih MAG postupkom u nadglavnom položaju (PD) u zaštiti mešavine gasova. Uzorci su zavarivani sa različitim parametrima zavarivanja i sa različitom pripremom spoja – dubina spoja, a ispitivanja su vršena nedestruktivnim metodama (vizuelna kontrola, ispitivanje penetrantima i magnetnim česticama) i destruktivnim metodama –zatezanje, savijanje i tvrdoća.
- СтавкаLAYER THICKNESS INFLUENCE OF MACRO- AND MICROSTRUCTURE QUALITY OF 3D PRINTED PARTS(Faculty of Engineering, University of Kragujevac, 2019) Đurić, Aleksija; Gojković, Ranka; Marković, Biljana; Moljević, Slaviša; Anić, JelicaIn this paper will be analyzed the influence of the layer thickness on the micro and macro structure of the parts obtained by 3D printing, i.e. fused filament fabrication (FFF) technology. Specimens for analysis will be printed on the 3D printer Zotrax M 200, and the macro and microstructure will be done on the VHX 6000 microscope. It will be shown in the paper that by increasing the thickness of the layer, the time required for the production of the part will be significantly reduced, but also the quality of the surface is also significantly affected.
- СтавкаMEASUREMENT OF TORQUE ON THE CARDAN SHAFT EMBEDDED IN THE FREIGHT VEHICLE(Faculty of Engineering Hunedoara, University Politehnica Timisoara, 2015) Milutinović, Miroslav; Đurić, Aleksija; Trifković, Spasoje; Vučetić, NikolaBefore analysis, development or improvement of existing structure of drive unit or gearboxes, the load that appearing in exploitation must be known. This paper presents a method of load (torque) measurement, on the cardan shaft embedded in the freight vehicle, using strain gages. The aim of the study is to determine torque variation depending on the exploitation conditions (road surface, speed transmission, vehicle load, etc). The measurement was performed for different road characteristics (vehicle movement on flat terrain, up and down the slope). Results are presented using tables and diagrams, and percentage utilization of the power drive unit, embedded into freight vehicle, was calculated based on obtained values of torque. Obtained results have an important role for designers because they give a general insight in the load on the cardan shaft , which represent the basis for future development or redesign of power unit or gearboxes and basis for forming of specter of gear load and bearing embedded into gearbox.
- СтавкаMicrostructure and Fatigue Properties of Resistance Element Welded Joints of DP500 Steel and AW 5754 H22 Aluminum Alloy(MDPI, 2022-02-14) Đurić, Aleksija; Milčić, Dragan; Burzić, Zijah; Klobočar, Damjan; Milčić, Miodrag; Marković, Biljana; Krstić, VladislavThe modern concept of lightweight design (LW) requires the application of different materials in one structure (multi-material structures). The structure of different materials has a good perspective for application in the automotive and aerospace industries but only if it is possible to achieve a quality joint between different materials. The most used technology for joining different materials in the automotive industry is Resistance spot welding (RSW). Due to different mechanical, physical, and chemical properties, the joining of different materials by RSW technology does not provide a quality joint, and accordingly, alternative technologies for joining different materials have emerged. Resistance element welding (REW) was developed to enable joint of different materials. This paper presents the welding of AW 5754 H22 Al alloy (1.0 mm-thick) and DP500 steel (1.5 mm-thick) using novel REW. The peak load, absorption energy, microstructure, microhardness and fatigue strength of the REW joint has been investigated. The joint of the same materials has been done also using conventional RSW to compare some results. The results that will be presented in this paper show that that REW can achieve reliable joining of the two materials at relatively low welding currents compared to RSW. Using REW process with a significantly lower welding current, satisfactory mechanical characteristics of the weld joint can be achieved, so peak load is between 2300–2500 N, displacement is between 2.5–3 mm and the absorption energy is between 3.3–5.7 J. REW joints showed fatigue strength with the fatigue limit of 882 N.
- СтавкаMicrostructure and Fatigue Properties of Resistance ElementWelded Joints of DP500 Steel and AW 5754 H22 Aluminum Alloy(MDPI, 2022) Đurić, Aleksija; Milčić, Dragan; Burzić, Zijah; Klobčar, Damjan; Milčić, Miodrag; Marković, Biljana; Krstić, VladislavThe modern concept of lightweight design (LW) requires the application of different materials in one structure (multi-material structures). The structure of different materials has a good perspective for application in the automotive and aerospace industries but only if it is possible to achieve a quality joint between different materials. The most used technology for joining different materials in the automotive industry is Resistance spot welding (RSW). Due to different mechanical, physical, and chemical properties, the joining of different materials by RSW technology does not provide a quality joint, and accordingly, alternative technologies for joining different materials have emerged. Resistance element welding (REW) was developed to enable joint of different materials. This paper presents the welding of AW 5754 H22 Al alloy (1.0 mm-thick) and DP500 steel (1.5 mm-thick) using novel REW. The peak load, absorption energy, microstructure, microhardness and fatigue strength of the REW joint has been investigated. The joint of the same materials has been done also using conventional RSW to compare some results. The results that will be presented in this paper show that that REW can achieve reliable joining of the two materials at relatively low welding currents compared to RSW. Using REW process with a significantly lower welding current, satisfactory mechanical characteristics of the weld joint can be achieved, so peak load is between 2300–2500 N, displacement is between 2.5–3 mm and the absorption energy is between 3.3–5.7 J. REW joints showed fatigue strength with the fatigue limit of 882 N.
- СтавкаMJERENJE OBRTNOG MOMENTA NA KARDANOVOM VRATILU UGRAĐENOM U TERETNO MOTORNO VOZILO(Mašinski fakultet, Univerzitet Istočno Sarajevo, 2014) Milutinović, Miroslav; Đurić, Aleksija; Trifković, Spasoje; Vučetić, Nikola; Marković, Biljana; Antunović, RankoZa analize, razvoj ili usavršavanje postojeće konstrukcije pogonskog agregata ili mjenjačkog prenosnika potrebno je prije svega poznavanje opterećenja koje nastaju u toku eksploatacije. U radu je predstavljen način mjerenja opterećenja (obrtnog momenta), na kardanovom vratilu ugrađenom u teretno motorno vozilo, primjenom mjernih traka. Cilj rada je utvrđivanje varijacija obrtnog momenta zavisno od uslova eksploatacije (podloge puta, stepeni prenosa, opterećenja vozila, i dr.). Mjerenje je izvršeno za različite putne karakterisitke (kretanje vozila po ravnom terenu, uz i niz nagib). Rezultati su predstavljeni tabelarno i pomoću dijagrama, a na osnovu dobijenih vrijednosti obrtnog momenta izračunato je procentualno iskorišćenje snage pogonskog agregata ugrađenog u predmetno vozilo. Dobijeni rezultati imaju značajnu ulogu za konstruktore jer daje sveobuhvatnost opterećenja na kardanovom vratilu, a koji predstavljaju podlogu za budući razvoj ili rekonstrukciju pogonskog agregata ili mjenjačkog prenosnika, te osnovu za formiranje spektara opterećenja zupčanika i ležaja ugrađenih u mjenjački prenosnik.
- СтавкаMULTI-OBJECTIVE OPTIMIZATION OF THE RESISTANCE SPOT-WELDING PROCESS PARAMETERS FOR THE WELDING OF DUAL-PHASE STEEL DP500(Institute of Metal Materials and Technologies, 2021) Đurić, Aleksija; Miličić, Dragan; Klobčar, Damjan; Marković, BiljanaResistance spot welding (RSW) is still the most used form of welding in the automotive industry, primarily for welding steel. One of the advanced steels used in the automotive industry is dual-phase steel, so it is important to properly select the welding parameter for these steels. Therefore, this paper presents multi-objective optimization in the RSW welding process of DP 500 steel. The paper considers three different mechanical characteristics i.e., the failure load (F), failure displacement (l) and weld nugget diameter (D), as all these welding characteristics play significant roles in evaluating the quality of spot welding. The results show that the welding current is the most influential parameter with respect to the mechanical characteristics. The effect of welding time on the weld quality is the least significant. The optimal parameters for welding DP 500 steel obtained in this paper are weld current 8 kA, electrode force 4.91 kN and weld time 400 ms.
- СтавкаOSNOVNI PRINCIPI I PRAVILA PRIMJENE LAKOG DIZAJNA U MAŠINSTVU(Mašinski fakultet Istočno Sarajevo, Univerzitet u Istočnom Sarajevu, 2014-12) Đurić, Aleksija; Marković, Biljana; Pelkić, Srđan; Marković, Biljana; Antunović, Ranko; Kraišnik, MilijaKroz ovaj rad biće predstavljeni osnovni principi i pravila primjene lakog dizajna pri konstruisanju mašinskih sistema. Takođe, rad će dati odgovore na pitanja koji je cilj i koje su strategije primjene lakog dizajna, koji se to materijali koriste za izradu i kako na pravi način izabrati adekvatne materijale, a da se kao rezultat dobije, ne samo smanjenje težine konstrukcije, nego i da se ona učini ekološki i ekonomski prihvatljivom. Cilj je da se naučnom, nastavnom i privrednom ambijentu približi ova savremena metoda u konstruisanju mašinskih sistema, koja će, u bliskoj budućnosti, predstavljati ključ za opstanak na svjetskom tržištu za sve kompanije iz oblasti mašinske industrije.
- СтавкаParameter optimisation and failure load prediction of resistance spot welding of aluminium alloy 57547(2019) Đurić, Aleksija; Klobčar, Damjan; Milčić, Dragan; Marković, BiljanaThis paper will also present single objective optimization and Failure load prediction of Resistance spot welding of Aluminium alloy 57547. The experimental studies were conducted under varying welding currents I, electrode forces F, welding times T, pred preheating currents IA. The settings of welding parameters were determined by using the Taguchi experimental design of L9 Orthogonal array method. For optimization and prediction will be used analysis of Signal-to-Noise (S/N) ratio and Response surface modelling RSM.
- СтавкаPRODUCT DEVELOPMENT PROCESS REGARDING TO CUSTOMER EMOTIONAL NEEDS(Faculty of Mechanical Engineering, University of Montenegro, 2017) Marković, Biljana; Ivanović, Lozica; Đurić, Aleksija; Tomović, RadoslavA successful development of a new product implies satisfaction of customer’s requirements to the level of their individual wishes which include emotions as well. A new or innovative product should be designed to support customer needs, including the customer’s persona which can be done by including feelings or emotions into interaction with the product. Customers tend to make a decision about a product based on their perception, values and reflections, so designers and manufacturers should consider making emotional design a bottom line in a product development. Therefore, the aim of this paper is to describe evaluation of customer needs regarding to product development process.
- СтавкаRESEARCH OF ADHESIVE AL– SHEET JOINTS IN THE DEVELOPMENT OF LIGHTWEIGHT STRUCTURES(Faculty of Engineering Hunedoara, University Politehnica Timisoara, 2023) Marković, Biljana; Đurić, Aleksija; Perendija, Marija; Imre, KissAdhesion is a major element of the bonding technologies used today. This way of joining meets the requirements of mechanical load, with high reliability of the product, and in connection with the production and climatic conditions. Bonding is the process of making inseparable bonds in mechanical engineering with non–metallic material, through adhesion and cohesion forces, without significant impact on the structure of the parts to be joined. Gluing (adhesive joint), as a way of making joints in mechanical engineering, is gaining importance in the development of spacecraft and aircraft, as well as the automotive industry. This requires high load–bearing capacity and stiffness, with minimal weight, so alloys such as aluminum and titanium are used. Adhesive joining is increasingly displacingthe dominant rivets when joining light metals, and is used to join thin sheets made of different types of materials. In this paper, the possibilities of adhesive joining and the characteristics of glued joints made of aluminum alloy AW– 5754 were researched, using static tests, and their fractography was analyzed.