Browsing by Author "Kabat, Oleh S."

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Development of Polymer Composite Materials for Friction Elements of Conveyor Equipment
(Technology Audit and Production Reserves, 2025) Sytar, Volodymyr І.; Kozyrko, Dmytro; Kabat, Oleh S.; Nazarenko, Andriy
ENG: The object of the study is materials with enhanced tribological properties intended for the friction components of conveyor equip-ment. One of the most critical issues is ensuring the wear resistance of friction units in conveyor systems, particularly under dry friction conditions. A promising solution involves the use of tribotechnical polymer composite materials (PCMs) based on aromatic polyamide.The research involved the use of modified graphite-containing systems based on aromatic polyamides filled with graphites of various dispersities and at different mass concentrations.Polymer composites were obtained based on aromatic polyamide modified with organosilicon fluid and filled with graphites differ-ing in nature and morphology. A correlation was established between the antifriction properties of the polymer compositions and both the filler content and graphite grade.Under dry friction conditions, the enhancement of antifriction properties is achieved by incorporating graphite into the aromatic polyamide in an effective concentration of 15–20%, at which a stable antifriction film forms on the counterbody surface, acting as a solid lubricant. In this case, the coefficient of friction and the linear wear rate of the material remain low, 0.1 to 0.15 and 0.5 to 1 × 10–⁹ m/m, respectively. A notable observation is that during friction, the graphite material wears away while the metal remains virtually unaffected. It was found that an excessive filler content (> 20%) leads to brittleness of the composite, which is a critical design limitation.As a result, the developed material can be effectively used for friction components operating under dry, lubrication-free conditions. This justifies its high utility and environmental benefits, as it eliminates the need for lubricants and their disposal. Compared to tradi-tional materials such as bronze, the proposed composites offer distinct advantages.
Effect of Clearance on Residual Stress and Quality in Rolled Tube-Tubesheet Connections
(Вісник Приазовського Державного Технічного Університету, 2025) Stovpnyk, Oleksandr V.; Kabat, Oleh S.; Ved’, Viktor V.
ENG: The quality of the tube-to-tubesheet joint is a critical factor determining the reliability and durability of heat exchangers and various types of industrial equipment operating under demanding conditions. This article examines the influence of the clearance between the tube and the tubesheet hole on the magnitude of residual stresses in the joint following the tube rolling process. The experimental component of the study involved precise measurements of actual clearances using specialized tools, the calculation of residual stresses through the mechanical stress relief method, and a comprehensive statistical analysis of the collected data to ensure accuracy and consistency. The findings revealed that the actual clear-ance typically exceeds the nominal value specified in design standards, and an increase in this clearance directly corre-lates with a rise in residual stresses within the joint. Notably, the highest stress levels were observed at clearances of 0.40 mm and greater, which may lead to localized plastic deformation, compromising the structural integrity and reducing the fatigue strength of the joint over time. Based on the analysis, the optimal clearance range was determined to be between 0.10 mm and 0.30 mm, as it strikes a balance between ensuring joint reliability and maintaining acceptable stress levels, thus minimizing the risk of premature failure. To validate the reliability of the experimental results, advanced statistical methods were employed, including the calculation of standard deviation to assess data variability and the application of Student's t-test to evaluate the significance of the observed trends. These calculations confirmed a statistically significant relationship between clearance size and residual stress levels, with particularly pronounced effects observed in joints involving small-diameter tubes, where tolerances are more critical. The outcomes of this research have practical impli-cations for the design and manufacturing of shell-and-tube heat exchangers, offering a pathway to optimize joint param-eters, enhance operational performance, and extend service life. Additionally, the study provides detailed practical rec-ommendations for quality control, including precise methods for measuring clearances with highaccuracy and evaluating residual stresses during production and maintenance processes.
Polymer Composite Materials of Special Purpose for the Aerospace and Rocket Industry
(Science and innovation, 2025) Kabat, Oleh S.; Bannyk, Natalia. G.; Voronyi, О. М.
ENG: Іntroduction. The advancement of the aviation and space industry has not only led to the creation of modern aircraft, rockets, and spacecraft but has also positively infl uenced related industries.Problem Statement. A critical requirement for aviation and space industry products is a high level of reliability and durability due to their continuous interaction with humans and the signifi cant costs of production and operation. This is particularly relevant for modern aircraft, rockets, and spacecraft, which operate at higher speeds, temperatures, and loads than their predecessors. Therefore, enhancing the reliability and durability of such products has become a pressing challenge. Purpose. The purpose of this research is to increase the reliability and durability of key components in rocket and space technology by replacing conventional materials with newly developed ones. Materials and Methods. The research has focused on polymer composite materials (PCMs) based on fl uoropolymers and aromatic polyamides, fi lled with dispersed materials derived from silicon dioxide and carbon. Results. Formulations and processing technologies for PCMs based on fl uoropolymers and aromatic polyamides have been developed. These materials have been shown to surpass most non-ferrous metals, their alloys, and low-carbon steels in strength (up to 285 MPa) while maintaining a low density (up to 1400 kg/m³). In terms of thermophysical properties, they have demonstrated exceptional heat resistance, with no thermal decomposition observed up to +365 C. Furthermore, parts manufactured from these materials have proven capable of operating in friction nodes without lubrication under normal loads of up to 2.5 MPa. Conclusions. The developed polymer composite materials based on fl uoropolymers and aromatic polyamides exhibit a high level of mechanical and thermal properties. Components made from these materials signifi cantly enhance the reliability and durability of modern aircraft, rockets, and spacecraft, representing a substantial ad-vancement for the aerospace and rocket industry
Polymer-Composites Based on Aromatic Polyamide and Aramid Fiber for Heavy-Duty Friction and Sealing Units
(Scientific-Technical Journal CHEMISTRY & CHEMICAL TECHNOLOGY, 2025) Kabat, Oleh S.; Boiko, Yulia
ENG: The paper substantiates the selection of a polymer and filler based on aromatic polyamide to create a material of friction pairs that operate in heavy-duty friction and sealing units of up-to-date vehicles and machinery. The effect of load and sliding speed on the tribological behavior of the initial aromatic polyamide and filled 15 %-aramid fiber was studied. As a result of tribo-logical studies, the terminal operating conditions of products made of initial aromatic polyamide and a composite based thereon, filled with aramid fiber, have been determined. The basic physical and mechanical properties of the materials under study have been deter- mined, and it is established that the introduction of aramid fiber into the aromatic polyamide contributes to a 10–15 % reduction in the level of the properties thereof due tothe occurrence of micro- and macrodefects of its structure.