Прегледај по Аутор "Vučetić, Nikola"
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- СтавкаANALITIČKO ODREĐIVANJE SOPSTVENIH FREKVENCIJA POGONSKOG VRATILA(Univerzitet u Istočnom Sarajevu, Mašinski fakultet Istočno Sarajevo, 2016-12) Vučetić, Nikola; Košarac, Aleksandar; Blagojević, Mirko; Antunović, Ranko; Marković, Biljana; Antunović, RankoModalna analiza je dinamička analiza linearnih sistema sa N stepeni slobode koja se zasniva na metodi razvijanja po vlastitim oblicima ili tonovima. Kroz ovaj rad je prikazano analitičko određivanje sopstvenih frekvencija oscilovanja pogonskog vratila mjenjačkog prenosnika snage DMB 6.80.235 primjenom Ojler-Bernulijeve teorije greda. Dobijeni rezultati su poređeni sa rezultatima sopstvenih frekvencija baziranim na ranijim istraživanjima, a dobijenim na osnovu eksperimentalne postavke, kao i numeričkim putem uz upotrebu software-a Ansys Workbench 12.1. Konačan cilj rada je dobijanje pouzdanog matematičkog modela sprezanjem parcijanih prenosnih funkcija.
- СтавкаBUCKLING ANALYSIS OF SIMPLY SUPPORTED SQUARE SYMMETRIC LAMINATED COMPOSITE PLATE(University POLITEHNICA Timisoara, 2023) Jeremić, Dejan; Radić, Nebojša; Vučetić, Nikola; Kiss, ImreTo usethe laminated composite plates efficiently, it is necessary to develop appropriate analysis theories to predict accurately their structural and dynamical behavior. The analysis of the behavior of the laminated plates is an active research area because of their complex behavior. The structural instability becomes an important concern in a reliable design of composite plates. The majority of the investigations on laminated plates utilize either the classical lamination plate theory (CLPT), or the first-ordershear deformation theory (FSDT). Various geometries of the plates subjected to compressive load are studied. The present work deals about a buckling analysis of simply supported symmetric composite plate with four layers. It is assumed that composite plate is surrounded by external elastic fundation. Composite plate is modeled by the finite element method and subjected to biaxial compression load. Governing equations are derivedbased on Classical Laminated Plate Theory (CLPT) and computed critical buckling loads were compared with numerical results.
- СтавкаEksperimentalno određivanje uticaja opterećenja na zagrijavanje kotrljajnog ležaja(Elektrotehnički fakultet, Univerzitet u Istočnom Sarajevu, 2017-03) Milutinović, Miroslav; Vučetić, Nikola; Trifković, Spasoje; Samardžija, Dejan; Milojković, SlobodanOsnovni zadatak ležaja jeste da omogući relativno kretanje obrtnih mašinskih dijelova tokom prenošenja opterećenja sa odgovarajućom tačnošću njihovog položaja. U toku rada obrtnih dijelova, na ležajima može doći do nastanka povišenih temperatura, koje mogu nastati usljed neispravnosti ležaja ili pak pojave preopterećenja. Radi određivanja uslova nastanka povišene temperature na kotrljanom ležaju usljed pojave preopterećenja, u ovom radu su vršena ispitivanja i upoređivanje rezultata neopterećenog i opterećenog ležaja poznatim masama. Za određivanje temperature ležaja korišćena je termovizijska kamera. Na osnovu dobijenih rezultata formiran je uporedni dijagram na kome se vidi tok zagrijavanja i hlađenja ležaja, za sva predmetna ispitivanja.
- 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 VERIFICATION OF NUMERICAL GEARBOX DRIVE SHAFT MODAL ANALYSIS RESULTS(University of Novi Sad, Faculty of Technical Sciences, 2016) Vučetić, Nikola; Blagojević, Mirko; Košarac, Aleksandar; Antunović, RankoThis paper shows the experimental determination of drive shaft DMB. 6.80.325 natural frequencies using available equipment for data acquisition and processing on the Faculty of Mechanical Engineering in East Sarajevo. The results were compared with the values of natural frequencies determined numerically in software Ansys Workbench 12.1 in which the mentioned shaft was modeled previously. Experimental results were processed in software packages MatLab and OriginPro.
- СтавкаFailure diagnosis and prognosis of sliding bearings(2019) Antunović, Ranko; Vučetić, Nikola; Halep, AmirSliding bearings are widely used machine elements from which the correct operation depends on the availability of many technical systems and great attention is paid to the study of the prediction method for sliding bearings. Problems that occur with sliding bearings lead to high levels of vibration and noise. One of the important parameters in the diagnosis and prediction of the failure of sliding bearings is the thermal analysis. In addition to these parameters, frequent vibration spectrum analysis, oil film thickness and other relevant parameters are often used. Using advanced technologies, it is possible to significantly reduce the duration of measurement, and on the other hand increase the accuracy of diagnostic methods. Phase logic is a mathematically formalized mode of representation modeling uncertainty. In this paper, a selection of damage in the operation of a sliding bearing has been made and the way of diagnosing these problems is shown. Methods that integrate several diagnostic parameters into one show reliable methods of early detection of slip bearing damage.
- СтавкаFurther Investigation of the Repetitive Failure in an Aircraft Engine Cylinder Head - Mechanical properties of Aluminum alloy 242.0(2020) Vučetić, Nikola; Jovičić, Gordana; Krstić, Branimir; Živković, Miroslav; Milovanović, Vladimir; Kačmarčik, Josip; Antunović, RankoAluminum alloys are widely used in military and aviation industry due to their properties such as low density and high strength. During the aircraft operation there are mechanical failures of various structural components caused by numerous mechanisms such as corrosion, material defects, high cycle fatigue and the like. One of the frequent mechanical failures on air-cooled piston engines is the cylinder head cracking. This paper is the continuation a comprehensive research of the Lycoming IO-360-B1F aircraft cylinder head failure. The failure of this type has already occurred during flight and about 50 failures like this have been registered from around the world, some of them with a fatal outcome and therefore require detailed research. The paper consists of machining of the tested specimens and their testing at many different locations and in many different laboratories throughout Bosnia and Herzegovina, Serbia and Slovenia. This paper is based on a research that includes the experimental analysis of mechanical properties of Aluminum alloy 242.0 which is a constituent material of the cylinder head of the Lycoming IO-360-B1F aircraft engine on which a crack appeared. Based on chemical, metallographic, static and dynamic experimental tests of the material properties, Aluminum alloy 242.0 static and fatigue properties were obtained, S-N curve was formed and endurance limit was determined. Results of numerical simulations of experiments, confirmed by experimental results, were performed to make numerical procedures reliable due to further research. The results of the research are planned to be implemented in numerical modeling of the cylinder assembly stress-strain state under workload and in further numerical research of Lycoming IO-360-B1F cylinder assembly integrity assessment.
- 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.
- СтавкаINTEGRITY ASSESSMENT OF AN AIRCRAFT CYLINDER ASSEMBLY WITH A CRACK(Associated Publishers, 2022) Vučetić, Nikola; Jovičić, Gordana; Antunović, Ranko; Sovilj-Nikić, Sandra; Košarac, Aleksandar; Jeremić, DejanThe repeatability of the air-cooled piston engine cylinder assembly failure due to a crack in the cylinder head, as well as its severity from the aspect of crew and passenger safety were the main motives for our research. In this paper an integrity assessment of a cylinder assembly with a crack was performed. By modeling cracks of different lengths in the cylinder head and considering the values of stress intensity factors and J-integral values at a given crack length on the one hand and determining the critical values of these fracture mechanics parameters on the other hand, the stability of the crack was examined. As part of the research, the dependence of the crack length on the stress intensity factor was established. The methodology proposed in this paper can be adapted to assess the integrity of other similar structural elements
- СтавкаISPITIVANJE ZAMORNIH KARAKTERISTIKA LEGURE ALUMINIJUMA 242.0 S CILJEM PROCJENE INTEGRITETA AVIONSKOG CILIDARSKOG SKLOPA SA PRSLINOM(Mašinski fakultet Istočno Sarajevo, Univerzitet u Istočnom Sarajevu, 2022) Vučetić, Nikola; Jovičić, Gordana; Antunović, Ranko; Milovanović, Vladimir; Krstić, Branimir; Jeremić, Dejan; Golubović, Dušan; Milutinović, Miroslav; Prodanović, SašaU cilju procjene integriteta cilindarskog sklopa avionskog motora Lycoming IO-360-B1F usljed pojave prsline na glavi cilindra potrebno je izvršiti niz eksperimentalnih ispitivanja legure aluminijuma 242.0 kao sastavnog materijala glave cilindra, među kojima je ispitivanje zamornih karakteristika na sobnoj i na povišenoj temperaturi. Dobijeni rezultati korišćeni su kao ulazni podaci u numeričkoj strukturnoj analizi razmatranog cilindarskog sklopa. Cilj ispitivanja materijala na zamor jeste odrediti dinamičku čvrstoću, odnosno najveći dinamički napon koji materijal pri određenom broju promjena opterećenja može da izdrži, a da pri tome ne dođe do loma.
- СтавкаKvantitativne metode izbora materijala električnih uređaja(Elektrotehnički fakultet, Univerzitet u Istočnom Sarajevu, 2016-03) Vučetić, Nikola; Adamović, Dragan; Jovičić, GordanaU radu je prikazan postupak izbora optimalnog materijala sastavnih elemenata električne pegle: kućišta, grijača i grijuće ploče, a pomenuti postupak se može primijeniti i za ostale slične električne uređaje. Predstavljene su dvije kvantitativne metode za izbor materijala: metoda uticajnosti karakteristika (digitalno-logička metoda) i metoda najmanjih odstupanja karakteristika od traženih (algebarski pristup). Definisani su osnovni kriterijumi, odnosno zahtjevi koje potencijalni materijali moraju da ispune, te je, na osnovu pomenutih metoda i softwarea Cambridge Engineering Selection (CES) izvršen pravilan izbor materijala.
- 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.
- 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.
- СтавкаMONITORING AND VIBRATION ANALYSIS OF HYDROAGREGATES(Mašinski fakultet, Univerzitet u Zenici, 2019) Antunović, Ranko; Vučetić, Nikola; Roljić, Milenko; Grahovac, Anđelko; Brdarević, Safet; Jašarević, SabahudinDirect control and diagnostic analysis of the situation turbine unit with strictly defined diagnostic methods, obtained good insight on the current state of the technical system and the actions implemented to maintain when it's really necessary. Parameters that carry the most information about the state of the system are certainly vibration parameters. Diagnostic approach lies in the fact that any malfunction machine produces a vibration predefined character. In this paper some of vibration analysis that have been done in Hidroelectric power plants on the HPP Vrbas.
- СтавкаPOČETNA ISTRAŽIVANJA S CILJEM RAZVOJA METODOLOGIJE ZA PROCJENU INTEGRITETA CILINDARSKOG SKLOPA AVIONSKOG KLIPNOG MOTORA(Mašinski fakultet Istočno Sarajevo, Univerzitet u Istočnom Sarajevu, 2018) Vučetić, Nikola; Jovičić, Gordana; Milovanović, Vladimir; Krstić, Branimir; Rakić, Dragan; Tomović, Radoslav; Antunović, Ranko; Golubović, Dušan; Košarac, Aleksandar; Jeremić, DejanU radu je dat pregled istraživanja mehaničkih otkaza različitih strukturnih elemenata vazduhoplova, kao u učestalost pojedinih mehanizama otkaza. Naveden je konkretan problem pucanja glave cilindra avionskog vazdušno hlađenog klipnog motora, te je predstavljen plan i cilj istraživanja u cilju razvoja metodologije za procjenu integriteta cilindarskog sklopa. U okviru planiranih istraživanja neophodno bi bilo izvršiti eksperimentalnu analizu mehaničkih karakteristika legure aluminijuma 242.0 na sobnoj i povišenoj temperaturi, kao i numeričku analizu cilindarskog sklopa. Prikazani su očekivani rezultati istraživanja, kao i zaključna razmatranja vezana za značaj samog istraživanja.
- СтавкаPOREĐENJE REZULTATA SOPSTVENIH FREKVENCIJA KARBONSKIH NANOCIJEVI DOBIJENIH METODOM KONAČNIH ELEMENATA (MKE) I ANALITIČKOM METODOM(Mašinski fakultet, Univerzitet Istočno Sarajevo, 2014) Vučetić, Nikola; Radić, Nebojša; Milutinović, Miroslav; Trifković, Spasoje; Košarac, AleksandarKroz ovaj rad je izvršeno poređenje rezultata sopstvenih frekvencija karbonskih nanocijevi dobijenih korišćenjem MKE analize i analitičke metode. Svako tijelo ima sopstvenu frekvenciju kojom osciluje ukoliko nije izloženo dejstvu spoljašnjih sila. Cilj rada je da se utvrdi jednakopravnost MKE analize i analitičke metode u izračunavanju sopstvenih frekvencija karbonskih nanocijevi. Izračunate su sopstvene frekvencije karbonskih nanocijevi kružnog i kvadratnog poprečnog presjeka putem MKE analize i analitičke metode, te je izvršeno poređenje dobijenih rezultata prikazanih tabelarno i na dijagramima. Na osnovu dobijenih vrijednosti može se zaključiti da se odstupanja u rezultatima pri određivanju sopstvenih frekvencija nanocijevi putem MKE analize i analitičke metode nalaze u dozvoljenim granicama.
- СтавкаQUANTITATIVE METHODS FOR MATERIAL SELECTION – MATERIAL PROPERTIES CHART(University Politehnica Timisoara, Faculty of Engineering Hunedoara, 2017) Vučetić, NikolaThis paper presents the selection of optimal materials for the production of basic constituent elements of electric iron: housing, heater and warming plate using material properties chart (map) quantitative method and Cambridge Engineering Selection software (CES). This work is a continuation and expansion of research. The results were compared with results from the paper [1] in which selection of mentioned constituent elements of electric iron materials was done using two quantitative methods: the method of properties influence (digital-logic method) and the method of minimum deviation of actual properties compared to required (algebraic approach).
- СтавкаSTATIC ANALYSIS OF GEARBOX DRIVE SHAFT(University Politehnica Timisoara, Faculty of Engineering Hunedoara, 2017) Vučetić, NikolaIn this paper, the structural analysis of the drive shaft of manual six-speed gearbox DMB 6.80.235 manufacturers Famos was performed. Static analysis was done in Ansys Workbench software, with the previously modeling of the mentioned shaft and the definition of boundary conditions and generating a finite element mesh. At the supports site, or bearings, springs are set and are presented by the final element COMBIN 14 whose stiffness is equivalent to stiffness of the supports.
- СтавкаTHE INFLUENCE OF CARBON FIBER ORIENTATION ANGLE ON BUCKLING PROPERTIES OF FOUR–LAYER SYMMETRIC LAMINATE UNDER BIAXIAL COMPRESSION(University POLITEHNICA Timisoara, 2022) Jeremić, Dejan; Radić, Nebojša; Vučetić, Nikola; Kiss, ImreThe present work focused on the buckling of four–layer symmetric laminate subjected to biaxial compression. Governing equations are derived based on Classical Laminated Plate Theory (CLPT). The composite plates are bonded by an internal elastic medium and surrounded by external elastic foundation. The influences of carbon fiber orientation angle and aspect ratio on critical buckling load are demonstrated for symmetric laminate. We analyzed four lamination scheme which fiber angle orientation is equal to 0°, 30°, 45° and 90°.
- СтавкаVibration and Temperature Measurement Based Indicator of Journal Bearing Malfunction(Faculty of Mechanical Engineering in Slavonski Brod; Faculty of Electrical Engineering, Computing and Information Technologies Osijek; Faculty of Civil Engineering and Architecture Osijek, 2018) Antunović, Ranko; Halep, Amir; Bučko, Mihael; Perić, Sreten; Vučetić, NikolaThis paper aims to present the development and implementation of the new malfunction indicator in journal bearings, based on vibrational and thermal records, called DFJB-Defect Factor Journal Bearing. Briefly, the indicator contains the specifically processed information about the bearing vibrations and temperature, on the basis of which the DFJB is calculated using fuzzy logic, and thus the state of the journal bearing may be determined. It should be pointed out that the DFJB is developed in a manner that besides the temperature and the total number of absolute vibrations, it may also integrate following parameters of monitoring: the parameters of rotating vibrations, vibrations spectrum, the thickness of oil film in the journal bearing, the intensity of the ultrasound emission of the bearing etc. These parameters may in certain cases offer more reliable malfunction identification. Experimental investigations conducted in this work, on real machine equipment and in real exploitation conditions, have shown this method to be reliable in the identification of malfunctions in journal bearings. As a result of implementation of DFJB, the time necessary to collect measuring data is significantly shortened, whereas the diagnosis procedure for journal bearings is highly simplified. This is particularly important in complex technical systems with a vast number of measuring points, which often result in the overload of the operator.