Radomir Radiša - Academia.edu (original) (raw)

Papers by Radomir Radiša

Zenodo (CERN European Organization for Nuclear Research), Jun 17, 2013

The aim of this paper is to demonstrate that it is possible to characterize the development and q... more The aim of this paper is to demonstrate that it is possible to characterize the development and quantify the area percentage of Cu-enriched phases in Al-5Si-(1-4)Cu alloys by applying a cooling-curve analysis. It is shown that several distinct Cu-enriched phases are manifested as peaks on the first derivative of the cooling curve. The total area percentage of the Cu-enriched phases is defined as the ratio of the area between the first derivative of the cooling curve and the hypothetical solidification path of the Al-Si-Cu eutectic to the total area between the first derivative of the cooling curve and the base line. These calculations, based on the cooling curve analyses, are compared with the image-analysis and chemical-analysis results in order to verify the proposed method. There is a good correlation between the measured and calculated values for the area of the Cu-rich phase in Al-5Si-(1-4)Cu alloys. Keywords: aluminum alloys, thermal analysis, cooling-curve analysis, image analysis Namen tega~lanka je predstaviti mo`nost ocene nastanka in koli~insko dolo~iti podro~ja s Cu bogatih faz v zlitinah Al-5Si-(1-4)Cu z analizo ohlajevalne krivulje. Pokazano je, da se ve~lo~enih, s Cu bogatih faz ka`e v obliki vrhov v prvem odvodu krivulje ohlajanja. Skupni dele`obmo~ja s Cu bogatih faz je dolo~en kot razmerje povr{in med prvim odvodom krivulje ohlajanja in hipoteti~ne poti strjevanja Al-Si-Cu-evtektika ter celotno povr{ino prvega odvoda krivulje ohlajanja in osnovno linijo. Izra~uni, ki temeljijo na analizi ohlajevalnih krivulj, so bili primerjani z analizo slik in rezultati kemijske analize, da bi potrdili predlagano metodo. Obstaja dobra korelacija med izmerjenimi in izra~unanimi vrednostmi podro~ij s Cu bogatih faz v zlitini Al-5Si-(1-4)Cu. Klju~ne besede: aluminijeve zlitine, termi~na analiza, analiza ohlajevalne krivulje, analiza slik

An analytical model for the optimization of the consumption of materials and energents in a typic... more An analytical model for the optimization of the consumption of materials and energents in a typical copper casting process based on a standard simulation procedure is presented. The proposed microeconomic analysis in correlation with the virtual manufacture of castings enabled a shortening of the time required to develop a product, as well as the fabrication of high quality castings, which could be a crucial contribution to the achievement of increased engineering adequacy and economic competitiveness. In this sense, the article demonstrates the beneficial employment of mathematical programming within a systematic economic analysis. The analyzed casting process is a part of the metallurgical manufacturing operations of the Copper Smelter and Refinery Bor, Serbia.

This paper presents the results of identifying and analyzing the phases present in the microstruc... more This paper presents the results of identifying and analyzing the phases present in the microstructure of 4 aluminum piston alloys with different chemical composition. Optical microscopy and scanning electron microscopy were used to study the microstructure of the samples and EDS analysis was used to identify the composition of the phases. The phase stoichiometry was identified by comparing the results of EDS analysis with the results reported in the studied literature. The results show that different intermetallic phases can appear depending on the chemical composition of the microstructure of aluminum piston alloys

Zenodo (CERN European Organization for Nuclear Research), Oct 24, 2018

Rezime: U radu je prikazano unapredjenje procesa livenja flotacijskih kugli bazirano na primeni n... more Rezime: U radu je prikazano unapredjenje procesa livenja flotacijskih kugli bazirano na primeni numeričke simulacije-savremenih softverskih sistema za optimizaciju i upravljanje parametrima procesa livenja. Koncept obuhvata virtuelnu proizvodnju, praktičnu realizaciju tehnološkog procesa korišdenjem unapredjene verzije alata za livenje i konačnu proveru kvaliteta odlivaka-flotacijskih kugli. Primenom metodologije prikazane u radu skraduje se vreme razvoja novog proizvoda i njegove prozivodnje u odnosu na tradicionalne metode testiranja putem pokušaja i pogreški.

Zenodo (CERN European Organization for Nuclear Research), Sep 18, 2013

Metalurgija, Jul 1, 2013

Recent development in the computer simulation technology caused a tremendous infl uence on a rapi... more Recent development in the computer simulation technology caused a tremendous infl uence on a rapid prototyping in casting process. These computational tools facilitate engineering work and urge moulding verifi cation in foundries. Among dedicated software packages the MAGMASoft is selected for availability reasons. Its eff ectiveness is proved with the simulation of moulding process of the cutting teeth for a bucket wheel excavator Use of MAG-MASoft enables a shortcut to a forceful and durable product, without internal cavities and micro-porosity. Such advancement of the moulding process is described in this paper.

International Journal of Metalcasting, 2015

This paper presents the results of investigating an Al-Fin bond between an aluminum piston alloy ... more This paper presents the results of investigating an Al-Fin bond between an aluminum piston alloy and austenitic cast iron. The part investigated utilized an austenitic cast iron insert for the first ring groove for application in a highly loaded diesel engine for increased wear resistance. A metallographic investigation using an optical microscope in combination with SEM/EDS (Scanning Electron Microscopy/Energy Dispersive Spectroscopy) analysis and 3D visualization of the quality of the intermetallic bonding layer was performed. The test results show that a metallic bond can be formed between the aluminum piston alloy and the austenitic cast iron.

Zenodo (CERN European Organization for Nuclear Research), Oct 14, 2011

Energija, 2022

Rezime-Rad opisuje inovativno rešenje pri revitalizaciji hidrauličnih turbina upotrebom tehnika r... more Rezime-Rad opisuje inovativno rešenje pri revitalizaciji hidrauličnih turbina upotrebom tehnika reverznog inženjeringa i virtuelne proizvodnje. Upotreba modernih digitalnih alata pri razvoju, projektovanju i proizvodnji pokazala je značajne prednosti kod unapređenja postojećih hidrauličnih turbina. Modelska ispitivanja hidrauličnih turbina nisu neophodna, jer se kao polazna osnova koristi postojeća geometrija lopatica turbinskog kola. Digitalni alati omogućuju da se na lak način osvoji geometrija, unaprede hidraulične osobine turbine i ostvari bolji stepen korisnosti, uz minimalne troškove. Cilј je da se prikaže optimizovani oblik i unapređenje radnih karakteristika Peltonove turbine.

Applied Sciences

On the way to building smart factories as the vision of Industry 4.0, the casting process stands ... more On the way to building smart factories as the vision of Industry 4.0, the casting process stands out as a specific manufacturing process due to its diversity and complexity. One of the segments of smart foundry design is the application of artificial intelligence in the improvement of the casting process. This paper presents an overview of the conducted research studies, which deal with the application of artificial intelligence in the improvement of the casting process. In the review, 37 studies were analyzed over the last 15 years, with a clear indication of the type of casting process, the field of application of artificial intelligence techniques, and the benefits that artificial intelligence brought. The goals of this paper are to bring to attention the great possibilities of the application of artificial intelligence for the improvement of manufacturing processes in foundries, and to encourage new ideas among researchers and engineers.

Proceedings of 47th International October Conference on Mining and Metallurgy Proceedings, Nov 2, 2015

This paper presents the application of new technologies in order to improve the exploitation prop... more This paper presents the application of new technologies in order to improve the exploitation properties of pistons for combustion engines made of aluminum alloy. Modern development of internal combustion engines, especially in the case of sports cars, imposed by the need to achieve maximum power, which in turn extremely increases the load on the individual parts of the piston. It has been shown that the hardness and wear resistance, otherwise inherent in aluminum alloys, for such high temperatures and extreme service conditions are not satisfactory. The idea is to protect the most burdened parts piston with aluminum matrix composites, which would be a solution to this problem. The aim of this paper is to review the research results achieved in this area.

Applied Sciences, 2020

This paper presents the application of machine learning in the control of the metal melting proce... more This paper presents the application of machine learning in the control of the metal melting process. Metal melting is a dynamic production process characterized by nonlinear relations between process parameters. In this particular case, the subject of research is the production of white cast iron. Two supervised machine learning algorithms have been applied: the neural network and the support vector regression. The goal of their application is the prediction of the amount of alloying additives in order to obtain the desired chemical composition of white cast iron. The neural network model provided better results than the support vector regression model in the training and testing phases, which qualifies it to be used in the control of the white cast iron production.

Facta Universitatis, Series: Mechanical Engineering, 2017

This paper presents the use of metaheuristic optimization techniques to support the improvement o... more This paper presents the use of metaheuristic optimization techniques to support the improvement of casting process. Genetic algorithm (GA), Ant Colony Optimization (ACO), Simulated annealing (SA) and Particle Swarm Optimization (PSO) have been considered as optimization tools to define the geometry of the casting part’s feeder. The proposed methodology has been demonstrated in the design of the feeder for casting Pelton turbine bucket. The results of the optimization are dimensional characteristics of the feeder, and the best result from all the implemented optimization processes has been adopted. Numerical simulation has been used to verify the validity of the presented design methodology and the feeding system optimization in the casting system of the Pelton turbine bucket.

The International Journal of Advanced Manufacturing Technology, 2016

This paper shows fuzzy and neuro-fuzzy intelligent systems for automatic control of mold filling ... more This paper shows fuzzy and neuro-fuzzy intelligent systems for automatic control of mold filling employed in casting plants. The concept of precision mold filling presupposes three key points in the process, i.e., precise pouring of the stream into the basin, maintaining constant level of molten metal in the basin, and finally, elimination of overflow of molten metal from the mold. The possibility of using fuzzy and neuro-fuzzy controls of mold-filling process was tested on a laboratory plant. Instead of molten metal, water was used, due to the approximate value of the Reynolds number of steel (1560-1600°C) and water at room temperature. Fuzzy and neuro-fuzzy controls of casting process were tested through many experimental attempts which have confirmed the possibility of application of these methodologies in the control of gravity casting process.

International Journal of Metalcasting, 2016

The paper presents a methodology of optimization of the gating system for sand casting using the ... more The paper presents a methodology of optimization of the gating system for sand casting using the genetic algorithm. Software package for computer-aided design/computer-aided manufacturing (CAD/CAM) was used as the support to the design and verification of the optimized gating system. The geometry of the gating system of sand casting in excavator tooth holder was the subject of optimization. The objective was to maximize filling rate given the constraints posed by both the ingate module and Reynolds number. Mold filling time has been presented as a function of the ingate cross section and casting height. Given the conditions above, as the result of the optimization, a complete geometry of the gating system has been defined. Numerical simulation (software MAGMA 5) has been used to verify the validity of the optimized geometry of the gating system.

Metallic Materials, 2016

This paper presents the results of testing the microstructure in the most critical zones of pisto... more This paper presents the results of testing the microstructure in the most critical zones of pistons made of aluminum piston alloys. The paper analyzes the shape, size and distribution of primary Si crystals and other phases in three most important piston zones (the edge of the combustion chamber, the area of rings groove and piston pin boss). The phase stoichiometry was identified by comparing the results of EDS analysis with the results reported in the studied literature. The results show that the necessary size, shape and distribution may be obtained in specific zones if appropriate solidification conditions are provided that are necessary for the formation of specific phases.