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An Increase in the Performance of Parts Made of Heat-Resistant Steels and Alloys
(2023) Zaichuk, Natalia; Shymchuk, Sergii; Pivnytskyi, Mykola; Shymchuk, Yurii; Szczot, Jacek
Increasing gas turbine engine parts’ heat strength and heat resistance is considered. Heat-resistant steels and alloys are most often used in highly loaded units and units of modern aerospace engineering, turbines, and power plants of the generator type. They work under high contact loads and temperatures and must simultaneously have sufficient heat strength and resistance. For this, metallographic studies of these materials were performed, and structures and the influence of alloying elements were analyzed. Special attention was paid to studying the microtopography of the working surfaces formed during the finishing operations of the part’s production. It is because their efficiency largely depends on the microtopography of the surfaces. Finishing operations of polishing the cylindrical surfaces of parts such as bolts and studs improve their disassembly during the overhaul of aircraft engine assemblies. While poor-quality polishing deteriorates the fatigue strength, such surfaces’ resistance to thermal fatigue does not allow them to achieve regulated performance. The study reveals the possibilities of increasing materials’ heat strength and resistance using appropriate heat treatment, particularly repeated heat treatment.
Pulling device for harvesting of Oleaginous Flax
(2024) Didukh, Volodymyr; Yaheliuk, Svitlana; Bodak, Volodymyr; Bodak, Maksym; Yaheliuk, Oleksandr
Oleaginous Flax is harvested using direct combining to obtain seeds. During this process – Stem-Fiber Mass (SFM) is disposed of by incineration or shredding. Both cases are harmful to the environment. With a sufficient amount of moisture and heat, a short non-oriented fiber is formed in a stem. The fiber creates a problem in the operation of the cutting device of the harvester. Especially, when harvesting Oleaginous Flax in the phase of full ripeness, when the fiber has strengthened and the woody part has turned into a shives. Thus, it is possible to save the grown crop by pulling the stems. Well-known technical means of pulling flax stems have a small width of grip, which affects their productivity. The solution to the problem lies in the creation of the harvesting working bodies, taking into account the width of the harvester. Such a device, when installed on the harvesting part of the combine, should not disturb its structure. As a section of the working body, a pair of rollers of the appropriate geometric shape, rotating towards each other, is offered. The technological process of stem pulling involves cap- turing a certain number of stems with rotating surfaces and clamping them in the space between the surfaces. Superimposition of surface rotation speeds and forward speed of the grain harvester helps pull the stems out of the soil. This approach makes it possible to preserve the grown crop of Oleaginous Flax and create prerequisites for the use of the SFM.
On the effect of vibrational capture of rotation of an unbalanced rotor
(2023) Yaroshevich, Nikolay; Grabovets, Vitalij; Yaroshevich, Тetjana; Pavlova, Irina; Bandura, Irina
The dynamics of an unbalanced rotor with a vibrating suspension axis and driven by an asynchronous electric motor of limited power is considered. Stationary (near stationary) modes of rotation of the rotor with a frequency equal to the vibration frequency of the axis are investigated. An explanation of the phenomenon of vibrational capture of rotation of an unbalanced rotor is given. The proposed mechanical interpretation of the effect allows deeper understanding of the classical results and conclusions. The obtained condition for the existence of a stationary mode allows us to estimate the frequency capture interval of the rotor. The case when the mode of vibration capture of rotation is not set is considered. For such a case, an expression for the vibrational moment is obtained, as well as an equation for slow motions. Attention is drawn to the possibility of occurrence in the considered modes of motion of slow (relative to the rotation frequency) rotor oscillations with sufficiently large amplitudes. It is demonstrated that the vibrational capture mode has the property of self-regulation; allows to stabilize the rotation frequency of an unbalanced rotor during load oscillations. Attention is drawn to the fact that in this mode of motion, there is certainly a transfer of energy either from the source of vibration to the rotor, or vice versa. The Sommerfeld effect in an oscillatory system with an inertial vibration exciter is represented by vibration capture of rotation of the vibration exciter by resonant oscillations of the carrier body. The theoretical results are confirmed by numerical modelling.

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