ISSN 0021-3454 (print version)
ISSN 2500-0381 (online version)
Summaries of the issue

Friction and wear

Universal methods and algorithms for estimating the wear rate of materials with a friction machine at constant and variable specific pressure are considered. Special attention is paid to the study of linear and volumetric wear. Simplified formula for the wear evaluation based on geometric functions decompositions in a Taylor series are proposed. The efficiency of applying a pair of friction with variable pressure by embedding a disk in a flat sample (the chord method) is proved. The dependence of linear and volumetric wear resistance on variable pressure is revealed. Time dependence of the wear resistance is established with the account for correlation coefficients for each of the sample of materials under consideration.
The wear resistance of polytetrafluoroethylene, its F4K20 composite, polyesterephyrketone, and ultrahigh-molecular polyethylene under sliding friction on carbon and alloy steels is studied experimentally. It is shown that in pairs of friction with alloy steel, a temperature regime can be created in which reactions of chemical interaction of Nickel with the polymer are activated. In the presence of polytetrafluoroethylene and its composite, the reactions are found to lead to formation of strong transfer films and an expansion of the range of workloads, and in the case of polyetherephyrketone and ultrahigh-molecular polyethylene --to a more intense heating of polymers and a reduction in the range of loads approximately in h
Running-in of Materials Under Reciprocating Friction Alina D. Bykova, Yury A. Fadin, Anton N. Belyakov, Markov Mikhail A., Andrey А. Shepelevskiy, Alexey O. Pozdnyakov
A new approach to constructing a reference curve based on the acoustic emission phenomenon is considered. The approach uses the acoustic radiation arising from the interaction of surface roughness during friction as a source of information. Several features of the reference curve formation for materials of the both contacting bodies are considered. A comparison is made of the traditional method of reference curve formation based on processing of profilogram data with the new method based on acoustic emission data recorded under friction. Employment of reciprocal-friction method makes it possible to construct simultaneously the supporting surfaces for both bodies involved in friction. It is assumed that this method will be a help in study of friction mechanisms of various materials. It is shown that running-in of soft and hard material leads to formation of the friction surface roughness with microcontact stain of the sizes proportional to the ratio of parameters of the friction pair materials strength to the shear.
Control of Сlamp Load of Interacting Tribocouple Musalimov Victor M, Pechenko Roman V., Abramchuk Mikhail V., Madina Tsvetkova
Several approaches to the development of the experimental base of tribology are proposed. The bifurcation component of sliding friction is investigated. An algorithm for automatic movement of the loading platform is developed, which excludes the operator's work. The originality of the solution to the loading problem consists in using the parameters of the structural model obtained at parametric identification of a dynamic system of friction interaction. A Tribal mechatronics unit is described, which provides the possibility of studying dynamic characteristics in real time. The apparatus of the theory of catastrophes is used to solve the problems.


A mechatronic device for unwinding and broaching rolled materials in discrete mode is studied. To reduce energy consumption, a spring drive with energy recovery is used, in which a pneumatic cylinder is installed to compensate for dissipative losses. Traditionally, such spring drives are used for reciprocating movements of working bodies with a constant mass. A special feature of the operation for unwinding roll materials in discrete mode is the change in the mass of the roll brought to the spring drive. The laws of mass change are established, and an algorithm is proposed that allows programmatic variation of the shutdown time of the pneumatic cylinder to ensure the maximum required speed of the carriage in the middle position. In this case, there is a free run-out of the roll and the packaging material is unwound, so that the tape hangs along the route. Further work cycles are performed in idle mode with minimal energy consumption. The change in mass is controlled by accounting for the number of cycles, and the mass reduction by a specific amount is set by the program. The results of the work are used when developing a mechatronic pneumatic system for the drives of a filling and packaging machine. It is supposed that the results can be used by developers of energy-saving technological equipment.
The problems of balancing vertical loads in various lifting devices are solved. Решены задачи уравновешивания вертикальных нагрузок в различных подъемных устройствах. Consideration is given to nonlinear spring accumulators that can be used to balance vertical loads in lifting devices, in various mechatronic spring drives with energy recovery, and in tactile sensors of industrial robots. The laws of motion that can be realized in spring drives with energy recovery, built on the basis of spring accumulators with an output rotary link and designed for stepper drives, drives with reciprocating and reciprocating movements, are analyzed. A comparative analysis of the main characteristics of various spring accumulators for solving the balancing problem is given, and recommendations for using different laws of motion are formulated.
Non-reversible step drives with a spring accumulator are considered, which allow reducing energy consumption when performing technological processes. Kinematic schemes of the step drive layout are analyzed, optimal designs of control units are selected, and an experimental installation of a non-reversible step drive with energy recovery is developed. Tests of a non-reversible step drive carried out with the use of the experimental installation makes it possible to compare previously obtained theoretical data with the experimental results. A comparative analysis of the time indicators of a pneumatic step drive and a drive with energy recovery is carried out. The obtained results demonstrate that the use of a spring battery can significantly reduce energy costs, and therefore application of spring drives is economically advantageous in the industrial sphere.
Development of Energy-Efficient Galloping Robots with Variable-Length Links Ivan I. Borisov, Kolyubin Sergey A, Roman A. Zashchitin, Stefano Stramigioli
An algorithm for structural-parametric synthesis of leg mechanisms of galloping robots that can move in an uncertain environment with external dynamic contact interactions and the use of relatively simple position and speed controllers is presented. Dynamic locomotion of galloping robots, whose leg mechanisms mimic the musculoskeletal system of animals, is provided by a variable-length link with passive regulation. The variable-length link, which is a connection of two solid-state links by means of a spring-loaded prismatic kinematic pair, is introduced into the resonance state to ensure energy-efficient dynamic locomotion, energy recovery when colliding with the floor, and leveling of the underlying surface irregularities.


Mass Spectrometric Method for Studying Gas Release During Friction in a Vacuum Alexey O. Pozdnyakov, Maksim I. Chernyshov, Semencha Alexander V. , Sergey N. Golyandin, Nikolaev Vladimir I, Voznyakovskii A. P., Yury A. Fadin
Functional scheme and implementation of a device for registering the composition and kinetics of formation of volatile products during friction in a vacuum with a time-of-flight mass spectrometer are described. The method efficiency is illustrated by results of experimental study of the friction of polyamide with metal and polymer counterbodies.
Designing a Spherical Scanner to Study the Spatial Characteristics of Antennas in the Near Zone Alexey N. Naumov, Svetlana Yu. Perepelkina, Vladislav A. Poddubny, Kovalenko Pavel P.
Special features of a spherical near-field antenna scanner design for studying spatial characteristics of antennas using the direct-drive approach for both axes of rotation are considered. The designed base of the spherical antenna scanning installation consists of a power bearing frame for placing the scanner design elements, and a base for mounting the signal receiver. The problem of placement of rotary devices is discussed; the devices include the angular node for rotation of the base of the fixed signal receiver in the vertical plane and the azimuth node for rotation of the object of study in the horizontal plane. Calculations of geometric characteristics, strength, rigidity, and stability of the structure are performed.
Improving the Design of Supports for a Rotary Viscometer Mark G. Evsin, Margarita A. Skotnikova
For a rotary viscometer with an elastic element, deviation of the measurements which arises as a result of friction in the measuring unit bearings is considered. Results of estimating the error due to friction moments in the bearings using ball bearings are presented. Methods of mathematical calculation of the error caused by friction for some bearing structures are described. A promising design of the supports of the measuring part of the rotary viscometer is proposed, which allows reduction of the error due to friction. Results of experimental determination of the error from friction in the supports of the proposed design confirms the effectiveness of the design application.


Evaluation of Thin Coatings Wear Anton N. Belyakov, Yury A. Fadin, Alina D. Bykova, Markov Mikhail A., Andrey А. Shepelevskiy
A new method is proposed for quantifying the wear of solids based on the acoustic emission phenomenon. The advantage of this method over others is that assessment of the amount of wear can be made directly in the friction of solids. The proposed method can be used to evaluate coatings of materials with thicknesses from units to several tens of microns. The performance of the method idea was tested on a titanium nitride coating on a titanium substrate.
Low-Rigidity Rubber Shock Absorbers for Pipe Mounting Vladimir L. Polonsky, Elena A. Tarasenko, Galina V. Tsvetkova
Rubber shock-absorbers installed in collars of pipe suspenders are considered. Rigidity characteristics of the shock-absorbers are analyzed. Influence of parameters of pipes on rigidity of the shock-absorber is considered. The main advantage of a standard shock absorber is its versatility and the ability to use it for a large range of pipes. The disadvantage of using it is the restriction on stiffness. The standard shock absorber is compared with a quasi-zero stiffness shock absorber, which allows realization of any stiffness characteristics.
Contact stresses in thin-layer metal-polymer sliding bearings are investigated experimentally. A method for evaluating stresses using capacitive sensors based on Dacron film with a double-sided metallized coating is proposed. Radial contact stresses and their distribution in thin-layer polyamide plain bearings with different mounting gaps and coating thicknesses are estimated. The experimental results shows that the maximum contact stresses depend to a large extent on the structural dimensions of the sliding bearings: the gap size and the coating thickness.