Papers by Lozica Ivanovic
Tehnicki vjesnik - Technical Gazette
The results of the experimental research of the power losses and efficiency of single-stage worm ... more The results of the experimental research of the power losses and efficiency of single-stage worm gearbox, which is designed for such purpose, are presented in this paper. Three worm pairs (coupled gears) ZI type with the same geometric characteristics were used in the research, where worms are made of the same material (hardened and ground steel type 42CrMo4) and worm gears are made of three different types of material (zinc-aluminium alloy ZA12, aluminium alloy A356 and tin bronze CuSn12). The main part of the research is conducted to investigate the application of new materials for the manufacturing of worm gears (alloys ZA12 and A356) and their impact on the power losses and efficiency in comparison to tin bronze CuSn12. The values of efficiency are determined for different operating modes of the gearbox, that is, for different values of input rotational speed and load, where different viscosity lubricants were used. Depending on the operating mode and measured operating temperatures, the calculation of power losses and coefficient of friction for all experimental worm pairs was performed. Based on the obtained results, it can be concluded that the best tribological characteristics has worm pair 42CrMo4/ZA12, which is the recommendation for the use of ZA alloy for manufacturing of worm gears as the alternative for tin bronze and other non-ferrous metals.
Gerotor pumps are a special type of gear pumps with internal trochoidal gearing. Due to their com... more Gerotor pumps are a special type of gear pumps with internal trochoidal gearing. Due to their compact design and simple structure, they are characterized by high reliability and low cost. They are represented in many applications, mostly in the automotive industry. Increasingly stringent environmental regulations require automotive manufacturers to improve vehicle design by increasing the efficiency of their components, including the gerotor pump. This paper presents a procedure for determining the optimal combination of trochoidal gearing design parameters, in order to improve the performance of a gerotor pump. Gerotor performance is affected by sliding velocity, volume efficiency and contact stress. An appropriate mathematical model was developed in order to analyze variation effect of gear design parameters related to value of the pump functional characteristics. In order to reduce the maximum contact stresses, forces and moments’ analysis was performed by analytical and numerica...
IOP Conference Series: Materials Science and Engineering, 2018
In this paper effects of welding on mechanical and microstructural characteristics of high-streng... more In this paper effects of welding on mechanical and microstructural characteristics of high-strength low-alloy steel joints is presented. Testing was done at models prepared with Vgroove butt joints that are done by two different welding processes. Considered welding processes were done by MMA or MIG for root pass and MAG for other passes with related consumables. Experimentally determined basic mechanical characteristics were put in correlation to relate ones that were numerically calculated. The experimentally obtained yield strength and tensile strength showed that welding process MMA/MAG provide better mechanical properties then MIG/MAG. It is implicated that selection of welding process at high-strength low-alloy steels is multi criterion analysis. If only proper welding is obtained, applications of high-strength low-alloy steel are adequate. Those applications caused specific problems related to its specific characteristics and properties especially weldability. As welding processes can be analysed from different aspects, selection of specific welding process at high-strength low-alloy steel are more complex.
Acta horticulturae, Aug 1, 2007
The harvesting is a very important phase during the process of chamomile production and has to be... more The harvesting is a very important phase during the process of chamomile production and has to be carried out in optimal agro-technical terms in order to achieve better quality of chamomile, i.e. high content of ether oil. There are different types of chamomile harvesters on the market with different quality of work and purchase price. In this paper we present two types of harvesters which have nearly equal work quality and market prices. We used statistical methods and methods of dynamic calculation for determining which harvester is more acceptable. Optimal technical solution is selected based on present value of cost purchase and harvester exploitation. Analysis is done for different values of discount rate, which are common in practice. Significant influence of value of discount rate on selection of chamomile harvester is determined. Limitary discount rate is calculated for which the present value of costs for different harvesters is equal.
International Journal of Fluid Power
Gerotor pumps are well known by a compact design, simple structure and low noise level, which mak... more Gerotor pumps are well known by a compact design, simple structure and low noise level, which makes them suitable for use in the automotive industry, and especially in hydraulic systems for engine lubrication. One of the main disadvantages of gerotor pumps is the inability to adjust to wear, which significantly reduces the pump efficiency. In order to mitigate the negative effect of the inevitable wear process, this paper presents a methodology for determining the optimal combination of trochoid gears design parameters for a defined aspect. An appropriate mathematical model has been developed to analyze the effect of changes in gear design parameters in relation to maximum contact stresses, pressure changes in gerotor pump chambers and wear rate proportional factor (WRPF). Verification of the developed models was performed by realizing physical pairs of gears and laboratory experiments with simulation of pump operating conditions. The results and conclusions presented in this paper,...
Tehnicki vjesnik - Technical Gazette
The results of the experimental research of the power losses and efficiency of single-stage worm ... more The results of the experimental research of the power losses and efficiency of single-stage worm gearbox, which is designed for such purpose, are presented in this paper. Three worm pairs (coupled gears) ZI type with the same geometric characteristics were used in the research, where worms are made of the same material (hardened and ground steel type 42CrMo4) and worm gears are made of three different types of material (zinc-aluminium alloy ZA12, aluminium alloy A356 and tin bronze CuSn12). The main part of the research is conducted to investigate the application of new materials for the manufacturing of worm gears (alloys ZA12 and A356) and their impact on the power losses and efficiency in comparison to tin bronze CuSn12. The values of efficiency are determined for different operating modes of the gearbox, that is, for different values of input rotational speed and load, where different viscosity lubricants were used. Depending on the operating mode and measured operating temperatures, the calculation of power losses and coefficient of friction for all experimental worm pairs was performed. Based on the obtained results, it can be concluded that the best tribological characteristics has worm pair 42CrMo4/ZA12, which is the recommendation for the use of ZA alloy for manufacturing of worm gears as the alternative for tin bronze and other non-ferrous metals.
Applied Engineering Letters : Journal of Engineering and Applied Sciences
Planetary gear trains have been applied for a long time in the automotive industry as an irreplac... more Planetary gear trains have been applied for a long time in the automotive industry as an irreplaceable part of automatic gearboxes. This paper presents, based on existing research, the kinematic analysis and evaluation of Ravigneaux gear trains, effects of power flow analysis and power loss, evaluation of utility effects of energy utilization through analysis of efficiency. It also illustrates research topics that analyse technical challenges of understanding and predicting dynamics and vibrations of planetary gear trains in the process of design of their configuration, optimization of given gear trains in reference to set criteria and affirmation of validity of their constructions by prototyping and prototype testing on the test stand.
Scientific Technical Review, 2010
Archives of Metallurgy and Materials, Jul 24, 2023
This paper presents experimental testing of the mechanical characteristics and properties of samp... more This paper presents experimental testing of the mechanical characteristics and properties of samples made of high-strength low-alloy steel with two different multi pass V grove butt welded joint. Two sample groups are tested: the root pass is made by manual metal arc welding process for the former and metal inert gas welding process for the latter. Other passes of those multi passes welded joints are made by metal active gas welding process. Further, the research included analyses of the experimentally obtained mechanical properties and load response of the samples in correlations to microhardness distribution and microstructural state at specific zones of the welded joints. Since both the chemical composition and microstructural state of high-strength low-alloy steel originate from special production processes their nature must be fully understood. Accordingly, the nature of the steels should directly impact not only the selection and definition of welding but the design process of mechanical constructions, too. From the practical aspect, mechanical characteristics and properties as well as load response of welded joints are crucial. But, sensitivity of those steels to inadequate welding technology and improper parameters or filler metal is high. On the other side, design codes and recommendations are not yet fully developed and precise. Results obtained in this research implicate that even small changes of welding technology causes the change of characteristics itself. Consequently, the steels development must be accompanied with the improvement of the welding processes and design modifications.
IOP conference series, Aug 10, 2018
This paper presents an analysis of the load distribution in the trochoid pump with the planetary ... more This paper presents an analysis of the load distribution in the trochoid pump with the planetary movement of the impeller. There are a lot of theoretical and numerical analyses conducted for the gerotor of the pump with fixed positions of the gear axis. Design of planetary gerotor pump has a different load distribution than gerotor with fixed axes. A planetary gerotor consists of a fixed outer gerotor gear with internal gearing and inner gear with an external gearing. The centre axis of the inner gear has a circular motion around the central axis of the fixed gear, because of the eccentricity on drive shaft. The special shape of the gerotor teeth forms chambers with varying volume that allows the flow and pressure of the fluid. During the pump working process the forces of different direction and intensity are present in each of the working chambers. It is necessary to determine the pressure in each of the chambers in order to obtain the load model of the gerotor. Load model will enable the calculation of load distribution in the zone of the maximum contact stresses. This calculation should help in dimensioning of the pump and the achievement of better performance characteristics.
Lecture notes in mechanical engineering, Oct 19, 2020
Gerotor pumps are a special type of gear pumps with internal trochoidal gearing. Due to their com... more Gerotor pumps are a special type of gear pumps with internal trochoidal gearing. Due to their compact design and simple structure, they are characterized by high reliability and low cost. They are represented in many applications, mostly in the automotive industry. Increasingly stringent environmental regulations require automotive manufacturers to improve vehicle design by increasing the efficiency of their components, including the gerotor pump. This paper presents a procedure for determining the optimal combination of trochoidal gearing design parameters, in order to improve the performance of a gerotor pump. Gerotor performance is affected by sliding velocity, volume efficiency and contact stress. An appropriate mathematical model was developed in order to analyze variation effect of gear design parameters related to value of the pump functional characteristics. In order to reduce the maximum contact stresses, forces and moments’ analysis was performed by analytical and numerical method. Through consideration of the gear tooth profile with technological gaps, their impact on the volume losses and gear ratio of the pump was identified. The verification of the developed models was carried out through the realization of physical gear pairs and performing of a laboratory experiments with simulation of pump operating conditions. These results establish valuable guidelines for constructors to design more efficient construction solutions of the gerotor pumps.
International journal of fluid power, Feb 6, 2021
Gerotor pumps are well known by a compact design, simple structure and low noise level, which mak... more Gerotor pumps are well known by a compact design, simple structure and low noise level, which makes them suitable for use in the automotive industry, and especially in hydraulic systems for engine lubrication. One of the main disadvantages of gerotor pumps is the inability to adjust to wear, which significantly reduces the pump efficiency. In order to mitigate the negative effect of the inevitable wear process, this paper presents a methodology for determining the optimal combination of trochoid gears design parameters for a defined aspect. An appropriate mathematical model has been developed to analyze the effect of changes in gear design parameters in relation to maximum contact stresses, pressure changes in gerotor pump chambers and wear rate proportional factor (WRPF). Verification of the developed models was performed by realizing physical pairs of gears and laboratory experiments with simulation of pump operating conditions. The results and conclusions presented in this paper, with an emphasis on the actual work processes, bring very important perspectives for the gerotor pumps design with improved performance.
IOP conference series, Aug 10, 2018
In this paper effects of welding on mechanical and microstructural characteristics of high-streng... more In this paper effects of welding on mechanical and microstructural characteristics of high-strength low-alloy steel joints is presented. Testing was done at models prepared with Vgroove butt joints that are done by two different welding processes. Considered welding processes were done by MMA or MIG for root pass and MAG for other passes with related consumables. Experimentally determined basic mechanical characteristics were put in correlation to relate ones that were numerically calculated. The experimentally obtained yield strength and tensile strength showed that welding process MMA/MAG provide better mechanical properties then MIG/MAG. It is implicated that selection of welding process at high-strength low-alloy steels is multi criterion analysis. If only proper welding is obtained, applications of high-strength low-alloy steel are adequate. Those applications caused specific problems related to its specific characteristics and properties especially weldability. As welding processes can be analysed from different aspects, selection of specific welding process at high-strength low-alloy steel are more complex.
IOP Conference Series: Materials Science and Engineering
Demands of today’s automotive industry are increasing; there is a constant tendency of weight red... more Demands of today’s automotive industry are increasing; there is a constant tendency of weight reduction and higher reliability of constructions. Pistons and piston liners for vehicles are mostly manufactured from aluminum-silicon alloys. With different manufacturing methods and/or the addition of some chemical elements, base alloy properties can be modified. Methods for hypereutectic aluminum alloys and composites manufacturing and their influence on material properties will be given in this paper. The influence of Si percentage in base alloy and how an addition of some chemical elements affects the properties of these materials will be observed as well.
Engineering Today
Electric energy consumed by the public lighting represents a significant item in the city public ... more Electric energy consumed by the public lighting represents a significant item in the city public sector energy consumption structure, which includes public buildings, public transportation and public lighting. Public lighting system is one of the most important public utility activities which is under control of local governments, which pay the costs of electricity, as well as maintenance costs. Public lighting affects the quality of life of citizens in cities through, among other things, reduction of traffic accidents by up to 35%, personal safety and reduction of social approaches. Cities and municipalities in Serbia are predominately using sodium and mercury bulbs for public lighting, but have been gradually replacing them with LED bulbs in the recent years. LED technology is a satisfactory, cost-effective solution due to low energy consumption, long service life, reduced investment and maintenance costs. Thus, there is not only a reduction in energy consumption of up to 70%, but...
IOP Conference Series: Materials Science and Engineering, 2019
In this paper the analysis of welding technology to mechanical properties of welded joints at hig... more In this paper the analysis of welding technology to mechanical properties of welded joints at high strength low alloyed steel S690QL is presented. Experimental testing was done at models with V-groove butt joints that are done by MMA or MIG for root pass and MAG for other passes of multipass welded joints with related parameters and consumables. Yield and tensile strength, so as answer to load of models are determined experimentally in order to analyses the effect of welding technology to resulted mechanical properties. On the basis of the obtained results it can be concluded that welding parameters have significant influence to mechanical properties of welded joints at high-strength low-alloyed steel. Furthermore, it can be concluded that welded joints with root pass done by MIG and other passes by MAG provide better mechanical properties. Presented research point out that welding parameters at high strength low alloyed steels must be selected and controlled precisely to obtain wel...
FME Transactions
Appropriate lubrication of the rolling bearing is needed to lower the friction between the surfac... more Appropriate lubrication of the rolling bearing is needed to lower the friction between the surfaces in mutual contact and their wear. A lubricant should completely separate the rolling elements from the raceways. The values that affect the efficiency and regimes of lubrication are analyzed in the paper, after which it is introduced a lubrication regime coefficient. This coefficient makes it possible to choose in a simple and fast manner an optimum combination of rolling bearing and lubricant based on the known shaft speed, external load, and rolling bearing operating temperature. For certain bearings with radial contact and certain lubricants, the lubrication regime dependence on the shaft speed and contact load is shown.
Tribologia : tarcie, zużycie, smarowanie, 2009
Summary This paper presents a theoretical model of gearing with a modified trochoidal profile app... more Summary This paper presents a theoretical model of gearing with a modified trochoidal profile applied to Gerotor pumps. Gerotor pumps belong to the category of rotating machines whose kinematics is based on the principles of a planetary mechanism with internal gearing. Using geometrical and kinematical models of the trochoidal gearing, we provide a detailed analysis of specific sliding at the contact points of the profiles, as well as the relations for its determination. Speci fic sliding is one of the most sig
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Papers by Lozica Ivanovic