Problems of Tribology

Multifactorial criterion evaluation of lubrication efficiency and wear resistance of friction units operating under extreme operating conditions

O. Milanenko — 2025-06-18

A new multifactor criterial approach to modifying lubricants by rheological properties and chemical composition is proposed in order to increase the lubricating ability of modified layers and wear resistance of friction units from the position of mixed lubrication conditions. Prevention of micro-EНD lubricating layer is achieved by a set of measures: implementation of stable micro-EHD lubrication by the criterion of lubrication mode; optimal viscosity class with an increase in the fraction of hydrodynamic pressure of modified layers relative to the contact pressure from micro-unevenness of rough surfaces by the pressure criterion; optimal type of lubricant by the rheological criterion; assessment of the appearance of a plastically deformed state by the criterion of plasticity; selection of the qualitative and quantitative chemical composition of active components in the lubricant to create durable modified layers with high structural adaptability and thermomechanical stability by the temperature criterion. A new concept for increasing lubricity and wear resistance for friction units operating in extreme operating conditions, using an appropriate criteria approach, takes into account: non-stationary friction conditions, the shape of local contact and friction kinematics, rheological properties of lubricating layers, contact temperature, and the composition of components in the lubricant

The influence of a binary alloy of the Al-Cr system on the tribological properties of ultra-high-molecular-weight polyethylene

O.I. Popil — 2025-06-18

The work studied the influence of a liquid-quenched binary alloy of the Al-Cr system with a chromium content of 5 wt.% on the tribological properties of ultra-high-molecular-weight polyethylene under friction without lubrication according to the “disk-pad” scheme and with rigidly fixed abrasive particles. We established that the introduction of 5-30 wt.% this alloy leads to a decrease in the intensity of linear wear and the abrasive wear rate of ultra-high-molecular-weight polyethylene by 2.8 and 2 times, respectively. On the other hand, this can be explained by the formation of a more strained Al-based solid solution lattice, since it is known that binary quenched from the liquid state aluminum-based alloys are characterized by a high degree of microstresses due to the significant difference in the sizes of Al-Cr atoms. A composite with a filler content of 20 wt.% has the best set of functional properties. We can recommend this material for the manufacture of tribotechnical (gears, sprockets, bushings, and plain bearings) and structural (rollers, gear wheels, and bearing housings) parts for agricultural machinery and the mining industry operating under conditions of impact-abrasive or fatigue wear.

Analysis of the influence of radial clearance in a bearing on its operating modes, taking into account mass and magnetic imbalance of the induction motor rotor

A. Goroshko — 2025-06-18

The article studies the problem of the journal motion of a three-phase induction motor rotor in a bearing. A simplified model of the journal motion is studied at the moment of journal separation and transition from the pendulum mode of journal motion to the impact mode. In this case, the elastic-damping properties of the bearing and the final rigidity of the rotor are ignored. The model takes into account the eccentricity of the rotor mass and the radial internal clearance of the bearing. In addition, the forces of unbalanced magnetic pull (UMP) caused by the magnetic eccentricity of the induction motor rotor, which is caused by the radial clearance of the bearing, are taken into account. It is analytically shown that the forces of UMP cannot be ignored, since even the rated clearance of bearings of low- and medium-power motors causes an unbalanced force commensurate with the force caused by the eccentricity of the mass. It is shown that without taking into account the UMP, an increase in the radial clearance leads to a decrease in the critical separation speed.

Probabilistic approach to assessing tribotechnical reliability indicators of friction units

M.O. Dykha — 2025-06-18

The article presents a theoretical and analytical review of the probabilistic approach to assessing the tribotechnical reliability of mechanical systems, in particular friction units. The influence of the random nature of loads and wear on the reliability of machine elements is considered. The feasibility of using distribution functions and probability density functions to describe the wear process is substantiated. Mathematical models are described in detail that allow determining the probability of element failure for given statistical characteristics of the load and permissible wear. Both constant and block load conditions are taken into account. The results of the study can be used in the design and operation of highly reliable tribotechnical systems, as well as for predicting their resource under conditions of operational uncertainty.

Improved mathematical model of the hydraulic drive of the garbage truck’s sealing plate mechanism taking into account the wear of its hydraulic cylinder

O.V. Bereziuk — 2025-06-18

This article is dedicated to the improvement of the mathematical model of the hydraulic drive of the mechanism of the garbage truck’s sealing plate, taking into account the wear of the hydraulic cylinder. An improved nonlinear mathematical model of the operation of the hydraulic drive of the garbage truck’s sealing plate mechanism is proposed, which takes into account the wear of the hydraulic cylinder and allows to numerically study the dynamics of the drive and determine that taking into account the wear of the hydraulic cylinder significantly affects the main parameters of the hydraulic drive of the garbage truck’s sealing plate mechanism. This study of the mathematical model was carried out using the fourth-order numerical Runge-Kutta-Felberg method with an adaptive integration step. Graphical dependencies were plotted to compare changes in the main parameters of the hydraulic drive of the garbage truck’s sealing plate mechanism without taking into account the wear of the hydraulic cylinder and with taking into account the wear. It has been established that the creation of a linearized mathematical model of the hydraulic drive of the garbage truck’s sealing plate mechanism, taking into account the wear of the hydraulic cylinder

Modeling of contact interaction and wear of the trolleybus contact insert-wire tribopair

K.E. Holenko — 2025-06-18

The article presents the results of numerical modeling of the contact interaction of the tribopair "contact insert - contact wire" of a trolleybus using the Ansys software environment. The main attention is paid to the analysis of the stress state and the prediction of wear of friction surfaces when modeling a stable frictional contact. Based on the constructed solid-state models of the contact insert and the MF-100 copper wire, a finite element mesh was formed and real conditions of operational loading were simulated. The distributions of contact pressure, frictional and equivalent stresses, as well as the nature of the contact spot were determined. Linear wear was calculated using the energy criterion, taking into account local frictional stresses and material hardness. The obtained results were compared with the available experimental data, which confirms the adequacy of the proposed model. The article also outlines the prospects for interpolation of short-term simulations into long-term operating modes by mathematical modeling of wear under variable load. The material is useful for predicting the service life of current collection devices and optimizing their geometry and materials

Study of the influence of rapidly quenched aluminum alloy on the wear resistance of ultra-high-molecular-weight polyethylene

А.-М.V. Tomina — 2025-06-18

The article considers the influence of 5-30 wt.% dispersed (50-100 μm) AlMnCrVZrCuMgW alloy rapidly quenched from the liquid state on the wear resistance of ultra-high-molecular-weight polyethylene under different operating conditions. In particular, we studied the behaviour of the metal-polymer composite under the action of rigidly fixed abrasive particles and friction conditions without lubrication according to the “disk-pad” scheme. This simulates real operating conditions in tribological joints of mechanisms of modern machinery. The results of experimental studies showed that introducing the rapidly quenched AlMnCrVZrCuMgW alloy into the composition of the polymer material contributes to a significant improvement in its wear resistance in different modes. Thus, the abrasive wear index decreases 1,7 times compared to pure ultra-high-molecular-weight polyethylene. The increase in wear resistance is due to the increase in the resistance of the ultra-high-molecular-weight polyethylene surface to mechanical stress. This is confirmed by an increase in the hardness of the material by 1,46 times. Morphological analysis of the friction surfaces revealed a decrease in the number and depth of the ploughing grooves, which is additional confirmation of the effective action of the AlMnCrVZrCuMgW rapidly quenched alloy as a strengthening phase.

Morphological Analysis of Surface Degradation in Phenolic Friction Composites Using Image Processing Techniques

F.F. Yusubov — 2025-06-18

This study investigates the surface degradation of phenolic-based brake friction composites under corrosive NaCl environments, emphasizing morphological analysis through digital image processing. The specimens were subjected to both vapor-phase and immersion conditions to simulate real-world corrosion scenarios. Surface changes were characterized via optical microscopy, Otsu-based grayscale binarization, and roughness profiling. The results indicated that vapor-phase exposure caused more uniform corrosion, but with smoother surfaces, while immersion led to localized and irregular damage. Post-corrosion dry friction tests showed a marked reduction in the coefficient of friction, attributed to surface smoothing and lubricious corrosion product formation

Study of the concentration effect and structure of multilayer spherical carbon nanoclusters on the carrying capacity of alternative fuels

Ie.V. Polunkin — 2025-06-18

The paper presents the results of tribological studies of the influence of nanoscale additives on the properties of ethanol and biodiesel fuels. The non-monotonic extreme nature of the dependence of the carrying capacity of liquid fuels on the content of nanoscale particles is revealed; this indicator changes most maximally in the region of ultra-low concentrations of nanoparticles (several ppm). The possibility of improving the synthesis and modification of carbon spheroidal nanoclusters by conducting high-frequency high-voltage synthesis in various organic solvents has been shown, which allowed to increase significantly the set of starting materials for the synthesis with the inclusion of various elements in the structure of CNSs. In order to increase the yield of carbon nanospheres during synthesis in the liquid phase, a reactor with a given angle of the interelectrode space was made for the first time for use in the synthesis process of "Jacob's ladder". For the first time, the hypothesis proposal has been made that individual carbon nanoparticles, obtained by high-voltage high-frequency plasma-chemical synthesis, which appear as spheroidal objects in electron microscopic images, are actually twisted coils of linear chain molecules of the polyyne type – carbynes.

Research into the possibility of improving the quality of electric arc coatings by nitriding

A. Lopata — 2025-06-18

An effective way to effectively change the characteristics of electric arc coatings made from crushed materials can be achieved by creating high-quality surface balls in them due to the use of different methods. chemical-thermal treatment. Research was carried out on the development and testing of the concept of molding chemical dry coatings based on the combined process of electrode deposition with technological processing of pulsed ion nitriding. It has been shown that duplex (combined) technology, which combines electric arc filing and nitriding, allows one to obtain a significant effect on non-structural properties, increased hardness, heat transfer and wear resistance of the part-coating system with a reduced degree of deformation of the part. An assessment was made of the possibility of moving the electric arc coatings from martensitic steels (40Х13, 95Х18), ferrite (Sv-08G2S) and austenitic (Х18Н10Т, 12Х18Н10Т) classes. further processing of nitriding.

Optimization of discrete structure of electrospark coatings

V. Antonyuk — 2025-06-18

The presented article considers the disadvantages of chromium coatings and shows the possibility of their elimination by obtaining coatings of discrete structure. The principle of coatings of discrete structure allows to organically combine physical processes underlying pulse hardening methods with a discrete structure determining their service properties. It is shown and substantiated that the method of electric spark alloying is the most suitable for applying discrete coatings, since this process is discrete by its nature. The advantage of discrete coatings is the absence of a softening effect when a brittle crack passes from the coating to the base metal due to excessively high adhesive strength. High cohesive and adhesive resistance of individual discrete sections of the coating is achieved by limiting normal stresses in the coating and tangential stresses in the plane of adhesive contact with the base by changing the size and shape of an individual section. This article is devoted to determining the optimal parameters of a discrete structure. The required coating design is determined by a calculation method based on a model that describes the stress-strain state of the coating.

The influence of hydrogen saturation on the wear mechanism of steel

V.V. Shchepetov — 2025-06-18

The tribological characteristics of hydrogenated steel 60C2 with different structural states were compared with the obtained results of studies of friction surfaces by physicochemical methods, which allowed us to draw a conclusion about the relationship between friction and wear indicators with the processes occurring on the surface of the material during friction, and the significant influence of hydrogen present in the contact zone on them. It was proven that during friction on the contact surface of hydrogenated steel 60C2, regardless of its structural state, the process of formation of secondary structures occurs, which determine the process of friction and wear of the material. Reduction of the wear intensity of steel 60C2 with a tempered martensite structure (300°C) is accompanied by the formation of secondary structures on the surface, which have a higher resistance and shield the base material from direct contact and destruction. In addition, the saturation of the material with hydrogen changes the nature and mechanism of formation of secondary structures, which in turn leads to a change in the mechanism of friction and wear of the material.

Texture of materials of elements of tribological systems of machines and mechanisms in non-equilibrium processing and functioning conditions

V.V. Aulin — 2025-06-18

The article is devoted to microtexturing of metal and polymer materials of tribological system elements, its influence on the characteristics and properties of working surfaces of samples and parts. Various types of microtexture of steel and composite materials based on zirconium oxide are considered. The mechanism of their formation is clarified. Mainly, the mechanisms of microtexturing are associated with the field of tension created during friction and laser processing. It is determined that laser processing of steel samples leads to combined microtexturing and a texture gradient along the depth of the surface layer of the sample. Texture in composites is revealed both during laser processing and during friction testing. It is shown that the revealed texture positively affects the operational characteristics of parts, increasing the level of reliability and wear resistance, as well as the tribological efficiency of tribocouplings of parts of assemblies, systems, units of machines and mechanisms