Машински факултет [Научни радови] / Faculty of Mechanical Engineering [Scientific papers]

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HOW TO REACH INNOVATIVE PRODUCT BY KNOWLEDGE TRANSFER?
(University Politehnica Timisoara, Faculty of Engineering Hunedoara, 2010) Marković, Biljana; Miltenović, Vojislav
The aim of every company, in modern conditions for the foreseeing, is to become available at global market. Creation of an innovative (new) product represents the key to success in global environment, while team work and use of demonstrated results of existing educative models represent the condition for creation of such a product. This paper shows results of knowledge transfer and implementation of the educative model KaLeP in education of mechanical engineers in Serbia. Major problem in modern world market is – how to create new innovative product which will fulfils all customers’ requirements and expectations? The above-mentioned means that new products are created in severe market competition which should fulfil customers’ expectations, even their individual wishes, which as result has striving for “innovative production”, and/or “innovative management”. The only possible solution in such actual environment conditions is application of one of the global development strategies, integrated product development. It is only mean for obtaining better, innovative design solution which is nowadays primary objective of any company. The objective of the university education of mechanical engineers is to impart the complex knowledge necessary for efficient product development in an industrial environment and to teach students the key abilities required for their professional life. Industry is searching for engineers with a university degree as a “problem solvers” and “creativity sources”.
Uticaj interakcije lokalnog i distorzionog oblika gubitka stabilnosti tankozidih profila otvorenog poprečnog presjeka na smanjenje nosivosti u postkritičnoj fazi
(Institut IMK "14. oktobar", 2012) Radić, Nebojša; Trifković, Spasoje; Jeremić, Dejan; Milutinović, Miroslav; Gašić, Milomir
U radu se razmatra problem određivanja vrijednosti lokalnog i distorzionog kritičnog napona tankozidih profila otvorenog poprečnog presjeka. Kod tankozidih nosača gubitak stabilnosti se dešava u zoni elastičnosti i pri relativno malim vrijednostima kritičnog napona. Sa povećanjem opterećenja u postkritičnoj fazi pri određivanju nosivosti potrebno je uzeti u obzir interakciju lokalnog i distorzionog oblika jer dolazi do značajnog smanjenja nosivosti u odnosu na slučaj kada se ta interakcija zanemaruje.
Design for Reliability Based Methodology for Automotive Gearbox Load Capacity Identification
(Assoc. of Mechanical Eng. and Technicians of Slovenia, 2013) Ognjanović, Milosav; Milutinović, Miroslav
Robust and Axiomatic design, a property-based approach in design, is applied and integrated into a new methodology for developing Functional Requirements (FR) or Design Parameters (DP). The reliability of the design structure and the elementary reliability of the design components are used as a functional requirement of the automotive gearbox, in relation to the service life and operation conditions, and also as a design constraint in analytical relationships. For this purpose, elementary reliability and allowable stress are defined in a specific way. The automotive gearbox, operating under varying and random operation conditions, is used as a case study. The same design structure has to operate under different operation conditions. In these circumstances, the carrying capacity as a functional requirement is related to the operation conditions and operation regime. The model presented in this paper, as well as a computer program, enable identification of this carrying capacity. This paper discusses an interdisciplinary and multi-methodological integrated approach to the presented task. Experimental data regarding the failure probability of gearbox components and the probability of operation conditions processing, the decomposition of gearbox structure, and the elementary reliability treatment as a component of design property are only some of the methods applied.
POSSIBILITIES FOR INTERACTIVE CONTROL OF MACHINE TOOLS IN THE VIRTUAL REALITY ENVIRONMENT
(UNIVERRSITY POLITEHNICA TIMISOARA, FACULTY OF ENGINEERING HUNEDOARA, 2013) Košarac, Aleksandar; Prodanović, Saša; Zeljković, Milan
The virtual product development is a modern approach in the product development process. Apart from the visualization itself, the virtual product development encompasses the whole range of testing in the virtual reality (VR) environment. Different testing performed in the virtual reality environment before prototype production can increase productivity and decrease development time. As an illustration of possibilities of performing different kind of testing in VR environment, this paper shows simulation in the VR environment of the process controlled by programmable logical controller (PLC) and MATLAB/SIMULINK. As an interface between VR and MATLAB/SIMULINK environment VR Toolbox library is used, and between MATLAB/SIMULINK and PLC controller that is OPC standard.
Identifikacija samoizavanih vibracija pri obradi struganjem primenom savremene dijagnostičke opreme
(Institut IMK "14. oktobar", Kruševac, 2013) Košarac, Aleksandar; Zeljković, Milan; Mlađenović, Cvijetin; Živković, Aleksandar; Gašić, Milomir
Pojava samoizazvanih vibracija pri obradi rezanjem je odavno uočena, ali i danas predstavlja vrlo aktuelno polje istraživanja kako sa stanovišta matematičkog modeliranja i predikcije, tako i sa stanovišta eksperimentalnog ispitivanja i upravljanja obradnim procesom. Razvojem NU mašina alatki i sve većom primenom visokobrzinske obrade, pomenuti problemi su postali još izraženiji, pa su detekcija i prevencija nastanka samoizazvanih vibracija postale suštinski važne za eksploataciju ovih obradnih sistema. U radu je prikazan način utvrđivanja trenutka nastanka samoizazvanih vibracija pri obradi struganjem, kao jednog od indikatora dinamičke nestabilnosti obradnog sistema, primenom savremene dijagnostičke opreme National Instruments i LabView i Matlab softvera. Takođe, na osnovu eksperimentalno dobijenih rezultata, primenom metode tangenti, određene su granične vrednosti dubine rezanja pri kojima dolazi do nastanka samoizazvanih vibracija, kao osnove za definisanje karte stabilnosti obradnog sistema, i identifikaciju najosetljivijeg elementa sa stanovišta dinamičkog ponašanja mehaničke strukture mašine alatke.
INTEGRATED SYSTEMS MANAGEMENT IN SMALL AND MEDIUM ENTERPRISES
(University POLITEHNICA Timisoara, Faculty of Engineering Hunedoara, 2013) Moljević, Slaviša; Rajković, Dragan; Marić, Bogdan; Medaković, Vlado; Đurđević, Slavoljub
Appearance of a number of management systems with various and sometimes divergent demands, demands for revise of optimal strategy on implementation of these standards in small and medium-sized enterprises (SMEs) and the attempt on their integration into integrated management system are suggested even more. Firstly question on choice and a reason for implementation of standards is raised. Management and employees expect benefits on the implementation and they pass and minimize the implementation barriers. Basic concept on integrated management system (IMS) into SMEs and analyze on reasons and advantages at IMS implementation are presented in this paper.
THERMO-MECHANIC ANALYSIS OF CEMENT TRANSPORT WAGON - IDENTIFICATION OF THE CAUSE OF CRACKS
(University Politehnica Timisoara, Faculty of Engineering Hunedoara, 2013) Milovanović, Vladimir; Rakić, Dragan; Živković, Miroslav; Vulović, Snežana; Milutinović, Miroslav
The paper represents a solution example of a specific engineering problem using thermomechanical analysis. The paper provides theoretical basis of numerical solving the problem of heat conducting through continuum using the finite element method. Calculation of heat conducting using the finite element method determines the temperature field used as an input for thermo-mechanical calculation. The basic task of thermo-mechanical calculation was the identification of the cause of cracks on the powder material transport wagon. After the analysis of the wagon crack causes, repair of the cracks is suggested. Repeating of the FEM analysis on the reconstructed model confirms that the wagon satisfies the criteria of static and fatigue strength appointed by the standards.
DETERMINATION OF LOAD SPECTRUM OF BUCKET WHEEL EXCAVATOR SRS 1300 IN COAL STRIP MINE DRMNO
(University of Zagreb, Croatia, 2013) Milčić, Dragan ; Miladinović, Slobodan ; Mijajlović, Miroslav ; Marković, Biljana
Toothed gear power transmissions are complex mechanical systems and their design is a very challenging engineering task that requires the application of common calculation procedures and contemporary designing methods. Operating conditions of the gear power transmission are important for the design process from the aspect of overload prediction and they are defined within the design process by the operating condition factor KA, which has a wide range of values (1 to 2.5), prescribing various operating situations. However, a good design of the toothed gear power transmission can be achieved if operating conditions are simulated and as such implemented in the calculation/design procedure. Such improvement in the design process can be done with the use of defined load spectra that accurately describe realistic operating conditions. The paper presents the results of tensiometric measurements of torque at the output shaft of the working wheel gearbox of the bucket wheel excavator SRs 1300 TAKRAF in the coal strip mine Drmno, and gives a definition of appropriate load spectra based on these tensiometric measurements. The load spectra are defined by applying the full cycle discretization method and as such afterwards used for the calculations/design of the working wheel of the bucket wheel excavator (gears, shafts, shaft keys etc.).
EXPERIMENTAL VERIFICATION OF DIFFERENT THEORETICAL APPROACHES FOR DEFINING FLD
(Faculty of Engineering Hunedoara, University POLITEHNICA Timisoara, 2014) Kraišnik, Milija; Vilotić, Dragiša; Šiđanin, Leposava; Petrović, Žarko
Workability of materials is the possibility of permanent changes in shape and dimensions of workpieces without cracking or other forms of damage to the structure. This property, which numerically valorized by size of limit effective strain, depends on type of material, the initial structure and processing conditions. This paper shows results related to the defining of FLD in bulk metal forming processes, based on theapplication of various theoretical approaches for determining of mean values of ß – factor and strainlimit.
THE INFLUENCE OF DEVELOPMENT AGENCIES ON THE DEVELOPMENT OF LOCAL COMMUNITIES
(University Politehnica Timisoara, Faculty of Engineering Hunedoara, 2014) Medaković, Vlado; Vasković, Srđan
Development of local communities dependent on the actions of development agencies, and particularly the effects of regional and local development agencies. Percent have data available that are potentially exploitable resources, can directly encourage the establishment of small and micro enterprises, and thereby facilitate and achieve sustainable development in all economic regions and local communities. Therefore it is necessary to form a regional development agency.
ANALYSIS OF DYNAMIC BEHAVIOR OF ROTATING MACHINES
(Faculty of Engineering Hunedoara, University Politehnica Timisoara, 2014) Antunović, Ranko; Veg, Aleksandar
Operating supervision and the condition monitoring of the rotating machines, deploying exact diagnostic methods, can be considered as a good insight into the current state of a technical system and exact assessment of maintenance necessity. In this way, one can survey a large scale of machines and processes, without loss of reliability, as well reducing the costs of maintenance and increasing system profitability. This is the paramount demand of the modern production philosophy. The paper, consideres importance of data selection and implementation of appropriate diagnostic techniques with particular emphasis on the analysis of the dynamic behavior of rotating machinery. Shown are some of the results of diagnostic analysis that have been conducted on machines in a real operation, applying advanced methods of technical diagnostics.
BIOMASS AND SUSTAINABLE DEVELOPMENT OF LOCAL COMMUNITIES
(University Politehnica Timisoara, Faculty of Engineering Hunedoara, 2014) Vasković, Srđan; Medaković, Vlado
Energy production from biomass is very specific because they use different technologies to obtain useful products. All the conversion of biomass into useful energy, efficiency factor describes the energy chain, from biomass resources as the energy source. This includes the collection and preparation of remains, and storage of organic residues to the end use and the conversion of biomass into heat or electricity. In Bosnia and Herzegovina there are many possibilities for both growing and using forest for energy producing. Successful examples taken from forestry management practice in EU countries can be useful for enterprises, owners, commerce and environment in BiH.
Dynamic Analysis of the Crane with Loading-unloading Trolley on the Slewing Platform
(Institut IMK "14. oktobar", Kruševac, 2015) Trifković, Spasoje; Gašić, Milomir; Radić, Nebojša; Milutinović, Miroslav; Gašić, Milomir
Dynamic processes of the cranes with loading-unloading trolley on slewing platform are very complex and require certain simplifications, although efforts should be made to theoretically involve widest range of impacts, with respect to degree of importance of individual impacts. The study of the dynamic behavior of the cranes is very important in terms of precise determination of stress state, as well as the other characteristics of the elements and supporting structures. Dynamic loads of the cranes occur during periods of non-stationary operating regimes of any of its mechanisms. In this paper, we obtain the differential equations of motion of the cranes for some specific cases of movement, based on general multi-mass model of the crane with loading-unloading trolley on slewing platform.
CREATE SISO STATE SPACE MODEL OF MAIN SPINDLE FROM ANSYS MODEL
(Faculty of Technical Sciences, Department for Production Engineering, 2015) Košarac, Aleksandar; Zeljković, Milan; Mlađenović, Cvijetin; Živković, Aleksandar; Kovač, Pavel
This paper shows identification of dynamic characteristics of working unit module main spindle, based on application of APDL ANSYS and MATLAB software. Single Input Single Output (SISO) state space MATLAB model will be developed from an APDL ANSYS main spindle model. The first step in defining the state space model is to define the eigenvector elements for all modes for only the input and output degrees of freedom. The next step is analysing the each mode contribution and sort them from the largest to smallest. One of the modal reduction technique is then applied, and modes with smallest contribution are simply truncated.
MORPHOLOGY OF STEEL C45E MICROSTRUCTURE DURING UPSETTING
(Faculty of Engineering Hunedoara, University POLITEHNICA Timisoara, 2015) Kraišnik, Milija; Vilotić, Dragiša; Šiđanin, Leposava; Petrović, Žarko; Šljivić, Milan; Stefanović, Milentije
Entirely understanding of all factors and mechanisms which influence nucleation and accumulation of ultimate level of material failure is necessary for adequate choice of material and rational projecting of metal forming technological procedure. The first step in research refers to the morphology characterization of material micro constituents during processing. This paper contains qualitative-quantitative analysis of morphology changes of ferrite and colonies of pearlite in the steel C45E microstructure during upsetting of cylindrical specimen with flat dies. Relative microforming level of ferrite grains was determined based on direct measurements, while indirect way has been suggested for determination of pearlite colonies forming ability. The approach is based on monitoring of area fraction changes of pearlite colonies in relation to area fraction of ferrite basis during upsetting process. The results of SEM testing have shown that ferrite grains and pearlite colonies are formed unequally.
VARIOUS APPROACHES TO DEFINING THE CRITERIA OF DUCTILE CRACK IN COLD BULK FORMING PROCESSES
(Faculty of Engineering Hunedoara, University POLITEHNICA Timisoara, 2015) Kraišnik, Milija; Vilotić, Dragiša; Šiđanin, Leposava; Stefanović, Milentije
In the process of metal forming continuous development and accumulation of material microstructure damage takes place. Reaching the critical level of damage, macroscopic damages occur which is manifested by crack and destruction of specimen (i.e. the crack) in metal forming processes. Optimal and rational design of technological forming processes means recognizing the location the crack occurs and strain limiting value. The ductile crack criterion is used for the purpose of solving this very complex task of material formability. In this paper we provided overview of theoretical and experimental approaches used for the purpose of defining the criteria of ductile crack based on reference literary resources.
NON-CONVENTIONAL CONTROL OF LEVEL AND TEMPERATURE IN THE FLOW TANK
(Faculty of Engineering Hunedoara, University Politehnica Timisoara, 2015) Prodanović, Saša; Nedić, Novak
Control of multivariable processes is greatly hampered due to the presence of mutual coupling (interaction) between their inputs and outputs. Therefore, the analysis of the mutual coupling, i.e. the determination of its measure, is very important for determining further activities towards the achievement of a satisfactory behavior of the controlled object. Present paper contains synthesis of decoupler for flow tank as a multivariable process in order to achieve decentralized control of level and temperature as its outputs. Afterward, PI controllers were tuned, and the quality of this nonconventional control was confirmed through the considerations of system time responses. The research was supported by simulations, and the results represent one of approaches in forming the concept for control of multivariable processes.
DEVELOPMENT OF NEW PRODUCTS IN INDUSTRY OF UPHOLSTERD FURNITURE
(University Politehnica Timisoara, Faculty of Engineering Hunedoara, 2015) Pelkić, Srđan; Đurić, Aleksija; Marković, Biljana; Vučinić, Radivojka
This 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.
Modelling and Enhancement of Organizational Resilience Potential in Process Industry SMEs
(MDPI, 2015) Arsovski, Slavko; Putnik, Goran; Arsovski, Zora; Tadić, Danijela; Aleksić, Aleksandar; Đorđević, Aleksandar; Moljević, Slaviša
The business environment is rapidly changing and puts pressure on enterprises to find effective ways to survive and develop. Since it is almost impossible to identify the multitude of complex conditions and business risks, an organization has to build its resilience in order to be able to overcome issues and achieve long term sustainability. This paper contributes by establishing a two-step model for assessment and enhancement of organizational resilience potential oriented towards Small and Medium Enterprises (SMEs) in the process industry. Using a dynamic modelling technique and statistical tools, a sample of 120 SMEs in Serbia has been developed as a testing base, and one randomly selected enterprise was used for model testing and verification. Uncertainties regarding the relative importance of organizational resilience potential factors (ORPFs) and their value at each level of business are described by pre-defined linguistic expressions. The calculation of the relative importance of ORPFs for each business level is stated as a fuzzy group decision making problem. First, the weighted ORPFs’ values and resilience potential at each business level are determined. In the second step, near optimal enhancement of ORPFs’ values is achieved by applying a genetic algorithm (GA).
STARTING A BUSINESS IN CONNECTION WITH THE USE OF RENEWABLE ENERGY SOURCES
(University Politehnica Timisoara, Faculty of Engineering Hunedoara, 2015) Medaković, Vlado; Vasković, Srđan
Developed countries as well as countries in transition and developing countries, defining short-term and long-term development strategy in the area of renewable energy sources and sustainable development, both at the state and at local and regional communities. United Nations (UN), European Parliament and other relevant international institutions and organizations in its acts and directives define a very clear and precise directions and frameworks for these the activities. A most marked political will to implement the rapid introduction of renewable energy sources demonstrate countries of the European Union and countries that follow the policy of the EU. Without delay need to be addressed problems of climate change, reduce high energy consumption and stop the disappearance of biodiversity and natural resources. The transition to a safe and sustainable economy with fewer negative effects on the environment will require in the near future, new economic policy at the global and local levels, as well as better strategic overview and management. It is necessary to urgently respond to the large number of unsustainable trends in production and consumption energy, social relations and habits of the people, and should strive and provide conditions for starting a business in that direction.

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