Problems of Tribology

Theoretical foundations of glow discharge nitriding of internal local recesses on metallic surfaces

M.S. Stechyshyn — 2025-09-22

This paper presents a comprehensive analysis of internal local recesses on metallic surfaces during glow discharge nitriding. Various types of recesses and their geometric features are studied to evaluate their impact on electric field concentration, which in turn affects the uniformity of surface modification. A field concentration criterion is introduced to quantify these effects, and an analytical framework is developed to describe the relationship between surface geometry and electric field parameters. The influence of the dimensions of internal recesses on field concentration is examined using numerical simulations. The results provide a deeper understanding of the mechanisms leading to localized variations in current density distribution on nitrided surfaces. The developed analytical tools are applicable for predicting and controlling electric field concentration indicators in glow discharge processes used for the surface modification of metallic components, which is critical for ensuring optimal mechanical and tribological properties

Analysis of frictional stresses and wear in the contact pair of a vehicle current collector

O.S. Kovtun — 2025-09-22

The article presents the results of numerical modeling of the operation of the trolleybus current collector pair "contact insert - wire" using the Ansys software environment. The distribution of frictional stresses (Frictional Stress) and contact pressures for two types of insert materials is analyzed: electrographite (Electrographite, parallel to plane) and copper-graphite composite Cu–40%C(f) 0.90 laminate. It was established that the real area of the contact spot is smaller than the entire surface of the gutter, which significantly affects the calculated values of the average frictional stresses and, accordingly, the wear forecast. For the electrographite insert, the average value of Frictional Stress was 0.439 MPa, for the copper-graphite insert – 0.599 MPa. The calculations showed that at a mileage of 450 km, the wear of the electrographite insert exceeds the permissible value, while for the copper-graphite one it is 2.1564 mm and is within the normal range. However, due to the higher hardness of the copper-graphite material compared to the copper wire, the wire itself can become the main element of wear, which is undesirable. It was concluded that the optimal option may be to use a material with intermediate hardness, which will provide a balance between the wear resistance of the insert and the preservation of the contact wire resource.

Research on the influence of rolling element geometry on the wear resistance of drilling equipment bearings

O.M. Makovkin — 2025-09-22

The article presents the results of experimental studies of the influence of the geometric parameters of rollers and raceways on the resistance of roller bearings to rolling element rotation and jamming. Failure of bearing assemblies due to roller rotation is a common cause of emergency equipment shutdown, which is accompanied by expensive repairs. The aim of the work was to determine the optimal ratio of roller length to its diameter (l/d) and the influence of raceway diameter (D) on critical wear, which leads to loss of roller stability. The research methodology was based on mathematical experimental design with variation of parameters l, d and D in laboratory conditions when simulating misalignment of the bearing assembly. An empirical relationship was established that quantitatively describes the relationship between roller geometry, raceway diameter and critical wear. The results showed that increasing l/d increases the resistance of the rollers to turning, while an excessive increase in D contributes to the growth of backlash and distortions. The most effective configuration was found to be the one with the maximum length and minimum diameter of the roller at a small value of D. The results obtained can be used for the design improvement of bearing assemblies, in particular in drilling equipment, in order to increase the resource and reliability of their operation

Analytical study of a hydraulic drive model for a municipal waste container overturning mechanism in a garbage truck considering the wear of friction pairs

O.V. Bereziuk — 2025-09-22

The article is dedicated to the analytical study of the improved mathematical model of the hydraulic drive of the mechanism for overturning a container with municipal solid waste into a garbage truck, taking into account the wear of friction pairs. As a result of the analysis of the performed numerical studies of the nonlinear improved mathematical model of the hydraulic drive of the mechanism for overturning a container with municipal solid waste into a garbage truck, taking into account the wear of friction pairs, a linearized version of this model was developed in the system of ordinary linear differential equations of the 2nd order. To carry out design calculations of new garbage truck designs, approximate analytical dependencies were obtained for the pressure in the hydraulic cylinder pressure line, the angular velocity and the angle of container overturning on time were obtained based on the proposed linearized mathematical model of the hydraulic drive of the container overturning mechanism in the technological operation of loading municipal solid waste into the garbage truck during the 1st phase – overturning the container to the equilibrium position, taking into account the wear of friction pairs. It was established that the analytical study of the linearized improved mathematical model of the hydraulic drive of the mechanism for loading municipal solid waste into a garbage truck, taking into account the wear of friction pairs during the 2nd phase – pouring waste from the container into the body of the garbage truck requires further research

Dynamic processes in surface layers of parts as a source of their multicycle failure under friction and wear

Y.O. Malinovskyi — 2025-09-22

During the operation of various machines and mechanisms, oscillatory movements may occur, excited by a non-stationary friction characteristic. These oscillations appear either at the contact area of two parts or in the zone located ahead of the moving part. In the contact area, a non-stationary friction force develops, leading to self-excited oscillations of the contact surface and to the occurrence of parametric oscillations in the area ahead of the active punch. At certain ratios of slip velocities and part movement speeds, self-excited and parametric motions may appear or disappear, as well as intensify or weaken. These oscillations are one of the causes of uncontrolled surface roughness (deformational), cracking, and spalling of interacting parts, as well as significant dynamic components during the loading of actuating, drive, and power mechanisms. Frictional and parametric oscillations in the surface layers of parts with deformation wave formation create residual plastic sinusoidal metal layers, which are sheared off during the interaction of parts. Due to the dynamic nature of interaction during friction, the forces acting in the contact plane (longitudinal) exceed the critical Euler force, which is a parametric load, and in some cases lead to dangerous parametric resonance. The work defines the frequency range near the parametric resonance, which is the area of dynamic instability ahead of the moving punch. The formulated and partially solved problem considers frictional and parametric oscillations during the interaction of parts, which lead to the formation of deformation waves.

Enhancing tribological system performance through intelligent data analysis and predictive modeling: A review

V.V. Aulin — 2025-09-22

The article presents a systematic analysis of the application of information technologies in tribology, including traditional methods, machine learning and artificial intelligence. The main goal of the study is to generalize and classify tribological informatics methods to improve the efficiency of tribological process analysis. The methodology is based on a review of key algorithms (ANN, support vector machines, K-nearest neighbors, random forest methods), determining their role in tribological research and analyzing information aimed at monitoring the technical condition, predicting behavior and optimizing tribological systems. It is determined that the use of artificial intelligence and machine learning algorithms significantly improves the accuracy of tribological system diagnostics, allows predicting their operational life and optimizing the operating parameters of tribological systems and machine mechanisms. A classification of tribological informatics methods is presented according to their functions: regression, classification, clustering, dimensionality reduction. This makes it possible to determine the most effective approaches for different types of tribological analysis. The practical focus of using intelligent modeling methods is the possibility of integrating the obtained results into production processes, which contributes to increasing the reliability of mechanical systems, reducing the costs of their maintenance and creating more accurate methods for predicting tribological characteristics, properties and tribological efficiency of the functioning of system components and assemblies of machines and mechanisms. It is shown that triboinformatics opens up new prospects for improving tribological research, providing more accurate monitoring, effective forecasting and optimization of tribological systems.

Self-lubricating glass composite magnesium carbide nanocoating

V.V. Shchepetov — 2025-09-22

The results of the study of the friction and wear characteristics of the developed nanostructured glass composite self-lubricating coatings are presented, the structural components which through magnesium carbide have a qualitative effect on the graphitization process due to the formation of a surface layer of carbide α-graphite, which, when combined with surface oxides characterized by low shear resistance, performs the role of solid lubricants under friction conditions. The positive role of the glass phase in the form of aluminoborosilicate, which affects the tribotechnical properties of coatings, has been established. It has been determined that the increase in adhesion strength is achieved by forming a surface layer of vitreous sodium silicate during spraying. It has been found that the intercalation of the graphite layer with dispersed particles of the surface structure does not significantly affect the tribotechnical characteristics. The developed nanostructured glass composite coatings showed high antifriction characteristics

The effect of polyimide fibre on the tribological properties of polytetrafluoroethylene

А.-М.V. Tomina — 2025-09-22

The article investigates the effect of discrete polyimide fibre on the tribological properties of polytetrafluoroethylene under friction conditions without lubrication, using the “disk-pad” scheme. It was found that the introduction of 2.5-12.5 vol% filler contributes to a significant increase in the wear resistance of polytetrafluoroethylene, up to 370 times. At the same time, the friction coefficient increases slightly, reaching a maximum value at a fibre content of 7.5 vol%. The decrease in the linear wear intensity of polytetrafluoroethylene is due to an almost twofold increase in hardness. We can explain the improvement in wear resistance by the formation of strong intermolecular bonds at the “matrix-fibre” interface, increased structural uniformity, and the formation of a stable transfer film during friction. Morphological analysis of the friction surfaces confirmed a reduction in the intensity of damage for the filled composites. On the surface of pure polytetrafluoroethylene, traces of plastic deformation, numerous plowing grooves, and signs of micro-cutting were observed, indicating the prevalence of the adhesive-fatigue wear mechanism. In contrast, the composite surfaces are characterized by a smaller number and depth of defects, which suggests a reduced influence of the adhesive component of the friction force and a transition to a pseudo-elastic wear mechanism.For polymer composite materials with an effective fibre content of 7.5 vol%, a set of tribological tests was conducted to determine the critical values of sliding speed and load that affect the linear wear intensity