Machinery - Repository of the Faculty of Mechanical Engineering, University of Belgrade
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50 godina Zajednice za jedinstveno upravljanje proizvodnim i tehnološkim resursima - JUPITER sistem i konferencija
No full textОвај рад представља подсећање и преглед трајања Заједнице за јединствено управљање
производним и технолошким ресурсима, која је познатија као ЈУПИТЕР систем. У циљу научне и стручне верификације резултата истраживачких пројеката и одређивања будућих праваца развoја ЈУПИТЕР система, покренута је и ЈУПИТЕР конференција као научно-стручни скуп чланова Заједнице и других чинилаца индустрије прераде метала, научно истраживачких институција и факултета.COMUNITY FOR UNIQUELY MANAGEMENT OF PRODUCTION AND
TECHNOLOGICAL RESOURCES - JUPITER SYSTEM AND CONFERENCE
This paper presents a reminder and overview of the duration of the Community for the uniquely
management of production and technological resources, which is better known as the JUPITER
system. In order to scientifically and expertly verify the results of research projects and determine the future development directions of the JUPITER system, the JUPITER conference was launched as a scientific and professional gathering of members of the Community and other members of the the metalworking industry, scientific research institutions and faculties
Synthesis and characterisation of metal–glass composite materials fabricated by liquid phase sintering
No full textIn recent years, there has been a global increase in environmental awareness, which has driven the application of natural materials or the synthesis of novel, environmentally compatible materials. Composite materials hold a prominent position among modern materials and are typically developed to achieve resistance to various damage mechanisms, thereby extending the service life of structures. This study presents the synthesis and characterisation of high-density metal–glass composite materials. The commercially available 316L stainless steel powder was used as the matrix material, while andesite basalt powder was used as the reinforcement phase. Andesite basalt aggregate, ground into powder, is a cost-effective, widely available, and environmentally friendly natural raw material. Powder metallurgy was employed to produce the composite materials. Sintering was performed at 1250 ◦C for 30 min in a vacuum. The density of the sintered composite samples was analysed as a function of andesite basalt content, with sintering conducted in the presence of a liquid phase. Composite materials were characterised using optical and scanning electron microscopy, X-ray structural analysis, and hardness testing. This study confirmed that the optimal combination of properties was achieved in the composite with 20 wt.% andesite basalt, present as a glass phase within the 316L steel matrix
The effect of natural aging on the tensile properties of PETG-CF filament
No full textParts manufactured using additive technology have been an excellent choice for prototyping for some time now. Certain materials, such as PETG, have shown a degree of similarity to metallic materials in terms of relationship between mechanical properties. These materials have demonstrated significant plasticity and toughness in the filaments, as well as the ability to form a "neck" during tensile testing.
Considering all of the above, the question arises as to whether PETG-CF can be used for manufacturing structural elements for smaller loads. In addition to standard tests, which have been performed many times, the question of aging has also emerged, i.e., the degradation of the mechanical properties of manufactured parts after a certain period.
This paper analyzes the change in strength between new samples and samples manufactured 10 months ago from the same PETG-CF filament
Application of a mobile digital image correlation system for on-site structural integrity assessment
No full textStructural integrity monitoring plays a crucial role in maintaining the safety and reliability
of industrial and civil infrastructure. Conventional inspection techniques often rely on contact
sensors and require operational shutdowns, limiting their efficiency and coverage. Digital Image
Correlation (DIC) provides a non-contact optical alternative that delivers full-field deformation and
strain data. Recent technological developments have enabled the adaptation of DIC into portable
configurations suitable for field deployment. This paper presents the practical potential of a mobile
DIC system for on-site assessment of pressure equipment and civil structures. The approach allows
inspection of pipelines, pressure vessels, bridges, and other load-bearing elements without disrupting
operation, offering early detection of localised deformation and enhanced decision-making for
maintenance planning. Although field implementation requires proper surface preparation and
control of environmental conditions, the system achieves laboratory-grade accuracy when correctly
applied. The mobile DIC concept therefore represents an efficient and reliable tool for real-time
structural evaluation, contributing to safer and more sustainable asset management
INFLUENCE OF THE JOINT GEOMETRY ON HEAT ENERGY, GENERATED DURING THE PLUNGE STAGE OF FRICTION STIR WELDING
No full textThe numerical simulation of friction stir welded T-joints made of AA2024 T3 is investigated. Analysis of heat generation due to friction and plastic work is performed, as well as of the reaction force in the normal direction during the plunge stage of the friction stir welding. The effect of joint geometry is studied for butt joints and T-joints produced from the same material. Different tool rotation speeds and tool pin lengths were considered for T-joint FSW welding. It was shown that the temperature at the root of the weld below the tool pin is lower in the T-joint than in the butt joint, due to the efficient conduction of the heat produced through the normal plate. Also, the reaction force was higher for the T-joint than for the butt joint; so, heat production by friction was more intense in comparison with the heat produced by plastic deformation. The reaction force was moderately increased for the tool with a shorter pin, increasing both components of the heat produced. An increase in the tool rotation speed decreased the resistance to the tool plunging into the T-joint, increasing the frictional heat and decreasing the amount of heat generated by plastic deformation.contr. 451-03-136/2025-03/200287, 451-03-137/2025- 03/200105 and 451-03-136/2025-03/20013
INTEGRATION OF ADDITIVE TECHNOLOGY AND MECHANICAL TESTING FOR THE ANALYSIS OF AUXETIC STRUCTURE CHARACTERISTICS
No full textThe Materials with a negative Poisson’s ratio are recognized as Auxetics materials. Compared to conventional materials it has the counter-intuitive property that during the compression the structure tends to contract and stretch when it expands. These particular attributes identified in the literature have encouraged further research on this topic. The flexible photopolymer resin is used for the test specimens, which have a cylindrical-shell based Auxetics structure. The test specimens are printed on an LCD printer with resin which gives structure ductile properties during the compression test. Using an industry camera the dimensional changes are captured for further research. With Digital Image Correlation method experimental results show different scenarios in varying the dimensions of the structure. Analyzed results give a foundation for future research, giving it a special focus on improving the quality of future tests and giving a perspective of potential applications and manufacturing variations of Auxetics structures
TENSILE STRENGTH ANALYSIS OF POLYMERS FABRICATED USING FUSED FILAMENT FABRICATION
No full textThis paper presents results of the experimental testing of 3D-printed specimens made from various materials. The applied technology for producing these specimens was Fused Filament Fabrication (FFF). The study was conducted in order to reach a conclusion about certain mechanical properties of examined materials, which find the vastest use in commercial 3D printing using FFF method. These materials include Polylactic acid (PLA), Acrylonitrile Butadiene Styrene (ABS), Acrylonitrile styrene acrylate (ASA) and Polyethylene Terephthalate Glycol (PETG). The specimens were produced according to the ISO 20753 standard in a direction perpendicular to the stretching direction to obtain maximum strength. The printer used for producing these specimens was Sindoh 3DWOX 1X. All the printing parameters remained the same for all specimens, excluding the nozzle and bed temperature, which were adjusted according to recommendations for specific materials. The testing was carried out on Shimadzu AGS-X 100kN universal testing machine with a crosshead speed of 1mm/min. The results were focused on elastic properties of materials and tensile strength. ABS showed the lowest values of ultimate tensile strength. PETG proved to be the least elastic, while PLA exhibited both the highest elastic properties and the highest ultimate tensile strength. However, PLA is not suitable for long-term use in places with elevated temperatures since it is prone to deformation. Based on the desired application and mechanical properties, the most suitable material should be chosen
Additive Manufacturing: A Key to Advancing Injection Molding Efficiency
No full textThe increasing demand for custom-made products, small-batch production, and improved process efficiency is driving manufacturers to adopt advanced strategies that minimize costs and production time. Additive manufacturing (AM) technologies address these challenges by enabling rapid prototyping, design flexibility, and advanced tooling capabilities. Initially constrained to polymeric prototypes, AM now supports a diverse material range, including metals and temperature-resistant polymers. Injection molding is a widely used manufacturing process for producing plastic parts with high precision and repeatability. However, traditional injection molding faces challenges such as high tooling costs, long lead times, and design limitations. This paper investigates solutions to these challenges through the application of additive manufacturing and rapid tooling technologies, emphasizing their potential to transform efficiency in injection molding
A NOVEL FINITE TIME STABILITY ANALYSIS OF A CLASS NONLINEAR FRACTIONAL ORDER MULTI-STATE TIME DELAY SYSTEMS: A NEW GRONWALL – BELLMAN INEQUALITY APPROACH
No full textIn this contribution, the finite-time stability analysis (FTS) for a class of nonlinear two=term fractional-order multi-state time delay systems (FOTDS) is studied. Based on a new Gronwall-Bellman inequality, a new FTS stability criterion for such systems are established in term of the Mittag-Leffler function. Finally, we provide numerical example to illustrate the applicability of the proposed stability conditions.No. 451-03-137/2025-03/200105 from 04. 02. 2025
Occupational health and safety performance in a changing mining environment: Identification of critical factors
No full textAlthough the mining industry plays a pivotal role in driving economic growth, it is also known for being one of the most dangerous work environments due to the high rates of injuries. Companies in the mining industry are faced with the challenge of applying occupational health and safety (OHS) measures in a manner to advance worker safety, health, and overall welfare, but also to improve productivity, enhance product and/or service quality, foster work motivation, and elevate employee satisfaction, and finally to enhance the quality of life for individuals and society. There is a noticeable research gap in the literature that simultaneously addresses multiple safety and health factors and their combined influence on employee safety satisfaction and performance. Hence, this paper seeks to address the gap in the existing literature by conducting a comprehensive analysis of how work equipment and environmental factors, human behaviour factors related to OHSs, and organizational climate factors influence operators’ safety satisfaction and how these, in turn, affects overall performance stemming from occupational health and safety initiatives. After developing a measurement and structural model, based on the data collected from the mining machinery operators, adequate statistical tests were used for evaluation and the hypotheses testing. The results of this study provide insight into the relationship between mining machine operators’ opinions on examined safety factors and employees’ safety satisfaction, where the organizational climate factors and safety satisfaction demonstrated a positive impact on safety performance, consequently resulting in their improvement. The theoretical implications of this study lie in establishing a comprehensive theoretical framework integrating safety factors, such as work equipment and environmental factors, human behaviour, and organizational climate, and their influence on the safety satisfaction of mining machinery operators. The practical implication of this research contributes to determining the critical safety factors (organizational support, co-worker support, supervisor support, worker engagement, the training related to OHS, and management commitment) that exert the most significant impact on the satisfaction of mining machinery operators and safety performance. These findings serve as a roadmap for decision-makers within mining companies, facilitating the identification of priority areas for enhancing both worker satisfaction and safety performance