Машински факултет [Научни радови] / Faculty of Mechanical Engineering [Scientific papers]
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- СтавкаInfluence of Surface Preparation of Aluminum Alloy AW-5754 and Stainless Steel X5CRNI18-10 on the Properties of Bonded Joints(MDPI, 2024) Zdravković, Nataša; Klobčar, Damjan; Milčić, Dragan; Zupančić, Matevž; Žužek, Borut; Milčić, Miodrag; Ðurić, AleksijaAdhesive bonding has proven to be a reliable method of joining materials, and the development of new adhesives has made it possible to use bonding in a variety of applications. This article addresses the challenges of bonding metals such as the aluminum alloy EN AW-5754 and the stainless steel X5CrNi18-10. In this study, the effects of laser cleaning and texturing on the surface properties and strength of two bonded joints were investigated and compared with mechanical preparation (hand sanding with Scotch-Brite and P180 sandpaper). The bonded joints were tested with three different epoxy adhesives. During the tests, the adhesion properties of the bonded surface were determined by measuring the contact angle and assessing the wettability, the surface roughness parameters for the different surface preparations, and the mechanical properties (tensile lap-shear strength). Based on the strength test results, it was found that bonded joints made of stainless steel had 16% to 40% higher strength than aluminum alloys when using the same adhesive and surface preparation. Laser cleaning resulted in maximum shear strength of the aluminum alloy bond, while the most suitable surface preparation for both materials was preparation with P180 sandpaper for all adhesives.
- СтавкаAn Intuitionistic Fuzzy Multi-Criteria Approach for Prioritizing Failures That Cause Overproduction: A Case Study in Process Manufacturing(MDPI, 2024) Sudžum, Ranka; Nestić, Snežana; Komatina, Nikola; Kraišnik, MilijaOverproduction is one of the most significant wastes of Lean that can occur in any manufacturing company. Identifying and prioritizing failures that lead to overproduction are crucial tasks for operational managers and engineers. Therefore, this paper presents a new approach for determining the priority of failures that cause overproduction, based on an intuitionistic fuzzy Multi-Criteria Optimization model and the Failure Mode and Effects Analysis framework. The existing vagueness in the relative importance of risk factors and their values is described using natural language words, which are modeled with trapezoidal intuitionistic fuzzy numbers. Determining the relative importance of risk factors is defined as a fuzzy group decision-making problem, and the weight vector is obtained by applying the proposed Analytical Hierarchy Process with trapezoidal intuitionistic fuzzy numbers. The compromise solution, as well as the stability check of the obtained compromise solution, is achieved using the proposed Multi-Criteria Optimization and Compromise Solution with trapezoidal intuitionistic fuzzy numbers. The proposed model was applied to data collected from a process manufacturing company.
- СтавкаCOMPRESSIVE PROPERTIES OF COMMONLY USED POLYMERS IN ADDITIVE MANUFACTURING PROCESSES(University Politehnica Timisoara, Faculty of Engineering Hunedoara, 2017) Kraišnik, Milija; Šljivić, Milan; Ilić, Jovica; Anić, JelicaProduction methods based on additive manufacturing technologies represent a powerful approach to the rapid and efficient production of complex prototypes and functional parts from different materials. This paper presents the procedure of development and production of a holder using a fusing deposition modeling process. Since compression is the dominant load on the holder in exploitation, mechanical testing was carried out and the results obtained can contribute to adequate material selection.
- 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.
- 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.