No 4 (2023)

Исследуются колебания и волны в периодических системах, образованных одинаковыми подсистемами, имеющими произвольную структуру. Найдены спектральные закономерности для таких систем. Показано, что их дисперсионные кривые состоят из ветвей, каждая из которых отвечает своей форме упругих колебаний подсистемы. Выявлено наличие в таких системах полос непропускания гармонического сигнала, найдены их границы. Получены формы колебаний в различных частотных диапазонах. Показано, что в системе возникают модулированные волны за счет модуляции низшими частотами, которые соответствуют колебаниям системы без учета упругих свойств составляющих подсистем.

This article discusses the influence of temperature on the mechanical properties of a fluoropolymer treated by λ irradiation above the melting point. The statement of the high efficiency of this strengthening technology on the tribological properties of the fluoropolymer–steel friction pair is substantiated. The changes in mechanical properties in a thin surface layer of the fluoropolymer as a consequence of heating to 400°C are studied using kinetic microindentation. The material hardness, elasticity modulus, total work of indentation, and its elastic constituent are analyzed. It is proposed to apply friction pairs containing radiationally strengthened fluoropolymer parts in the axial piston pumps of hydraulic systems in order to increase the probability of faultless operation.

The effect of a pulsed current on titanium tensile deformation obtained by postdeformation annealing after cold rolling of the coarse-grained and ultrafine-grained states has been considered. The effect of the duty cycle of the pulse current over a wide range on the shape of the stress–strain curves and mechanical properties has been studied. It is shown that an increase in the duty cycle results in an enhancement in the thermal effect of the current and a decrease in the flow stresses, strength, and plasticity, as well as in intense necking. A decrease in the duty cycle leads to the absence of heating and the occurrence of the electroplastic effect and an increase in the strength and plasticity, which depends on the structural state of coarse-grained titanium and the method of titanium production. The possible physical mechanisms of hardening associated with twinning, strain aging, and low-cycle fatigue have been considered.

The results of analytical study on the temperature regimes of the gearbox bearing units are given, and their diagnostic criteria are substantiated. We prove experimentally the possibility of practical application of the automatic thermal diagnostics based on the study of the thermal regimes of the bearing unit.

Study and assessment of the reliability of a joint of a circulation-loaded ring of a rolling bearing 50217 and a flange of the Yaroslavl Engine Plant gearbox demultiplier have been carried out. It has been found that, upon adding the dispersion of the sizes of the analyzed holes and shafts, a dispersion of gaps and interferences is formed, in which the probability of occurrence of interference fits (93%) prevails. After pressing, due to the collapsing of the roughness of the hole and the shaft, the probability of interference with a gap increases (51.7%). In addition, upon operating under the action of a load, the possibility arises that joints with an actual interference less than the smallest functional one (8.1 µm) can turn. It has been proven that, when shaft tolerance class js6 is assigned, interference with a gap will prevail in the joint, which will lead to rotation of the circulation-loaded bearing ring in more than 80% of the joints, significantly reducing the reliability of the demultiplier bearing assembly and the gearbox of the Yaroslavl Engine Plant engine as a whole.

Protective technological coatings for low-temperature deformation of semi-finished products and products from hard-to-deform alloys (titanium, zirconium, etc.) are considered. The process of low-temperature isometric product deformation made of the VT6 alloy, friction, and the separating properties of protective technological coatings are studied by compression of ring samples. Laboratory studies and industrial tests of pilot batches of coatings are carried out. Recommendations on the use of protective technological coatings are presented

Methods for graphical representation of the connection between the initial data and the main results of the design of worm gears are considered. Graphs have been developed that visualize the initial data, the resulting dimensions, and the sliding speeds in a wide range of gear ratios. Working with summary graphs prevents errors and significantly reduces the time for selecting transmission parameters in accordance with the performance criteria.

The change in the spectral density of a stress pulse during the operation of an explosive facility in the rock mass is simulated. An algorithm has been developed for calculating the distribution of the spectral density of the pressure pulse for nonstationary gas-dynamic processes, taking into account the physical and mechanical properties of rocks.