Machinery - Repository of the Faculty of Mechanical Engineering, University of Belgrade
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ВКЛАД РУССКИХ ПРОФЕССОРОВ-ЭМИГРАНТОВ В РАЗВИТИЕ МЕХАНИКИ И МАШИНОСТРОЕНИЯ В СЕРБИИ
No full textРассмотрены биографии двух поколений профессоров-эмигрантов из царской России, преподававших механику и различные области машиностроения в Белградском университете. В основном они взяты из историй факультета машиностроения Белградского университета и Сербского общества механики , изданных к их важным юбилеям, и дополнены данными из доступных исторических источников. Показан и детализирован огромный вклад русских профессоров в развитие механики и машиностроения в Белграде
SOME REMARKS ON THE BASIC PRINCIPLES OF ULTRASONIC WELDING OF CONDUCTORS IN THE AUTOMOTIVE INDUSTRY
No full textThe application of ultrasonic welding has increased over the last decade due to the rapid technological development and its availability at lower cost. In this paper ultrasonic welding of conductors is presented as one of the most important manufacturing processes in the automotive industry. Using this method of welding, conductor joints are created that represent a crucial part of any electrical installation such as wiring harnesses for vehicles. Additionally, connections between conductors and components, such as metal terminals, can also be achieved using the same welding process. These conductor joints or connections between conductors and terminals must provide high electrical conductivity and satisfying mechanical properties in order to create a safe and reliable product. The conclusions of this study provide some advantages of ultrasonic welding application particularly in the automotive industry, and further trends in this field
A New Approach to Fire Resistance Design of Boiler Room Building Structure
No full textis the inapplicability to industrial facilities in which energy is produced or distributed. In this paper a novel approach is presented in order to determine the necessary fire resistance of the building structure of a boiler room. The method of separating the boiler room from fuel storage, as well as storage and transport of fuel from storage to the boiler room are not considered in the paper.
The aim of this paper is to determine the necessary fire resistance of the building structure of a general boiler room. The analysis will include boiler rooms with boilers that use different types of fuels (gaseous, liquid and solid fuels). The proof of the adequacy of the class of fire resistance for building structure will be given independently using the Purt methodology (according to the
Euroalarm standard) while the obtained results will be verified by using the Gretener methodology - version TRVB according to the TRVB 100:2010 recommendations and Gretener methodology - version SIA according to the SIA81 recommendations. Assumed fire prevention and protection measures include: installation of an automatic fire alarm system; constant presence of the
person on duty next to the fire control panel; sufficient number of fire extinguishers before the arrival of the fire brigade; existence of appropriate fire hydrant installation; professional fire brigade located up to 5 km from the building; access to the boiler room is provided from three sides for the purpose of fire-fighting, i.e. there is at least one opening that can be used for fire-fighting purpose
on every 20 m of the walls that border the fire sector. Considering the initial assumptions from presented results it can be concluded that for boiler rooms, in which liquid fuel is not in
use, it is sufficient to provide fire resistance of the building structure of 30 minutes.Contract 451-03-137/2025-03/ 200105 - 4.2.2025
Identification of crack initiation cause in slewing platform horizontal plate of the excavator SchRs630
No full textA crack occurred on a lower horizontal plate of a slewing platform of bucket wheel excavator (BWE)SchRs630. Numerical calculation model of pylons, slewing platform and undercarriage was formed. Calculationswere performed using finite element method (FEM) for different load cases in order to identify load that causedthecrack. All the loadings repeat in cycles, particularly loading with inertial forces caused by bucket wheel boomandcounterweight boom masses while breaking slew drive, and also a workload causing bending of pylons. All theseloads cause (not high) stress concentration in this spot and could be the cause of a fatigue crack. To completethewhole picture of the structure behaviour dynamic analysis was performed. Simple redesign solution of this part ofthe structure was proposed.contracts no. 451-03-137/2025-03/ 200105 and 451-03-137/2025-03/ 200213 from 04.02.202
STRUCTURAL MODIFICATION OF THE CARGO HOLD DOUBLE BOTTOM FOR A MULTI-PURPOSE VESSEL
No full textIncreasingly, modern maritime vessels must demonstrate sructural flexibility to accommodate the growing
need for transporting various cargo types in response to evolving industry demands. As a result, regulatory
bodies, and their respective rules, regulations and standards, require that novel structural solutions are to be
verified through advanced structural assessments, including finite element analysis (FEA). Therefore, this
study focuses on FEA-based structural assessment and optimization of the double bottom and underdeck
reinforcement structure in the two cargo holds of a multi-purpose vessel originally designed for bulk cargo.
However, the vessel now also needs to carry standard 20-foot high cube containers, imposing a significantly
different loading scenario. While bulk cargo results in nearly uniform load distribution, containerized cargo
introduces concentrated point loads. The analysis accounted for container weights, gravity, and accelerations
due to ship motion. Von Mises stress criteria were used to evaluate the structural response, according to the
rules and regulations of two major regulatory bodies: Lloyd’s Register and International Association of
Classification Societies. The results indicated that the original structure could not withstand the new loading
demands according to the regulatory standards. Consequently, structural modifications were proposed and
implemented. The study highlights that even multi-purpose vessels, which are assumed to be suitable for
various cargo types by design, require structural modifications to safely accommodate containerized cargo.
The presented solution demonstrates how targeted reinforcements can ensure compliance with modern
classification society rules while enabling operational flexibility.Project no. 451-03-137/2025-03/200105 from 4 February 202
ADVISORY-BASED PRODUCT CONFIGURATOR USED IN CHILLER CONFIGURATION AND EVALUATION
No full textThis article presents the architecture and functional principle of an advisory-based
product configurator. The program is used to create new and modify similar product configurations and is intended for users without in-depth expertise in technical fields. Due to its architecture, the configurator is designed to utilise the knowledge stored in the knowledge database. The selection is based on a combination of fuzzy inference rules and mapping techniques. Knowledge
regarding the product is captured by using component-based matrices. The possibility of adding new knowledge and new rules is also provided. All this enables the configurator to link customer requirements and offers the possibility of selecting one or more products. In addition, it evaluates possible product variants based on the parameters specified by the user. The graphical
representation of the results obtained includes the product technical documentation as well as a matrix representation of all the selected components and modules. The functional principle and evaluation of the product selection are demonstrated using a case study of a chiller for installation in an industrial plant. During the selection and evaluation of the chiller, better system performance is achieved with a chiller that has a water-based condenser
On energy efficiency of tankers: EEDI, EEXI and CII
No full textThis paper aims to extensively analyze the energy efficiency of large tanker fleets, focusing on their compliance with the International Maritime Organization (IMO) requirements through the evaluation of design and operational indices. Despite an increase in energy efficiency studies, few have assessed large tanker fleets and their subgroups systematically, leaving a significant gap regarding the impact of regulations on different tanker sizes. The paper evaluates the energy efficiencies of tankers concerning Energy Efficiency Existing Ship Index (EEXI), Energy Efficiency Design Index (EEDI), and Carbon Intensity Indicator (CII), differentiating ships by size and type. It further explores and provides the potential reductions in speed and power for each subgroup of tankers, required to meet current and future energy efficiency requirements. The outcome shows that regulatory measures like EEDI, EEXI, and CII have significantly improved energy efficiency, but compliance remains challenging, with only 14.8% of ships meeting the EEXI criteria, especially for smaller ships, which face greater power reductions than larger ones. The results also indicate that the considered fleet of tankers does not operate at more than 60% of the available engine power and that the ships are already sailing at 8% lower speed than for which they were designed
Evaluation of Aerodynamic Coefficients of Supercritical Airfoil NASA sc(2) 0712: A Comparative Study of 2D and 3D Flow Models with Experimental Validations
No full textThis study presents a comparative numerical analysis of 2D and 3D compressible, turbulent flows around the supercritical airfoil NASA sc(2) 0712 at Mach number M = 0.5 using the finite volume method implemented in ANSYS Fluent, focusing on the estimation of drag coefficients in relation to existing experimental data. In addition, different types of computational grids and turbulence models are tested. The investigation aims to highlight the discrepancies observed between the two modeling approaches and their implications for aerodynamic performance predictions. Through rigorous numerical simulations and validation against experimental results, we demonstrate that 2D models often yield overestimated drag values due to simplified flow assumptions. In contrast, 3D simulations provide a more accurate representation of fluid behavior, resulting in closer alignment with experimental findings. By performing spatial computations of turbulent flow around a supercritical airfoil, it is possible to reduce the relative error of drag coefficients by less than 10%
Aerodynamic analysis of field wind turbine: a comparative study of computational methods with experimental validation
No full textThe study compares performance predictions from Blade Element Momentum Theory, Computational Fluid Dynamics methods, and experimental results for a 2.5 MW horizontal wind turbine across various wind speeds. The results indicate that Computational Fluid Dynamics or in complex flow conditions, although Blade Element Momentum Theory remains useful during the initial design stages. The analysis also underscores the influence of wind speed and shear stress transport on performance metrics such as turbine power output and flow characteristics. Despite certain modeling simplifications, such as the omission of detailed blade tip geometries, the findings suggest that both numerical methods exhibit trends consistent with the field experimental data. The study highlights the importance of detailed simulations for optimizing wind turbine performance and outlines future research focused on noise reduction and its impact on biodiversity
Structural optimisation of planetary gearbox components
No full textThe high-speed reduction in a relatively small space, coupled with a torque load capacity larger than that of any other standard transmission, positions planetary gear systems as one of the most vital components in gearing applications today. Structural analysis of a gear train is conducted using CATIA software, employing strain full tensor distribution analysis through Finite Element Method (FEM). The analysed natural frequencies and vibration modes of each component provide essential information for fine-tuning resonances away from the assembly's operating speeds. Based on these results, component dimensions are optimized using CATIA's optimizer module to achieve a structurally compact gearbox design. The minimization of gearbox mass serves as an objective function, with gear dimensions as variable parameters constrained by ultimate bending tooth root stress, safety factors, and critical frequencies expressed as inequalities. Structural optimization results are presented in tables, comparing initial natural frequencies with those obtained from the optimized solution. The final optimized design for each gear train component is also presented and discussed in the paper's concluding section. In conclusion, the paper outlines its primary objectives, summarizing key findings and proposing new ideas for further research to
enhance and optimize planetary gear transmissions in practical applications