Friction Assemblies Research Articles

Research of transformation process of barrier layers in antifriction bearing with solid lubricating filler at autoclave simulated operation

AbstractFor the time being, solutions to increase coupling durability are being searched for in a number of aspects: process design; physical and chemical, aimed at creating innovative and improving existing materials; physicometallurgical, aimed to find scientifically justified solutions to composition, structure, and property issues related to materials intended for production of components of friction assembly and methods to impact their near‐surface layers. An in‐depth study of kinetics of structural, phase and diffuse transformations is required in order to solve these problems. Researching the processes that occur when graphite‐based solid lubricants are in use, we will also examine strength and deformation properties of friction pair surface microvolumes. An objective of this paper is to study transformation processes of near‐surface layers in antifriction bearing while using solid‐antifriction lubricating fillers.

The frictional pebble game: An algorithm for rigidity percolation in saturated frictional assemblies

We present a fast, robust algorithm to determine rigid and floppy structures in two-dimensional (2D) assemblies of saturated frictional particles, based upon a generalisation (Lee and Streinu (2008) [11]) of the classical pebble game algorithm (Jacobs and Hendrickson (1997) [10]) for frictionless systems. By saturated, we refer to frictional systems for which all particle contacts involve sliding friction, which is relevant for certain frictional models and the study of incipient flow and stress-strain hysteresis. Whilst we do not present a mathematical proof of this method, we demonstrate validity via comparison with results from a classical method based on the network stiffness matrix over a diverse range of particle assemblies, including diluted bond networks and assemblies of cohesive, frictional particles.

Load-Bearing Capacity of Spiroid Gears of Mining Machine Drives under Peak Loads

The substantiated dimensionless criterion of jamming characterizes relationship between the temperature of the contact links of spiroid gearing and the load-bearing capacity of an oil film. Based on the review of the existing tribotechnical systems used in scoring resistance testing, a physical model of spiroid gearing is selected. The test data obtained on a rolling-and-disc scheme of a friction assembly are presented. The relations between the friction coefficient in the spiroid gearing and the unit load are determined for the steel–steel material couples in a range of slip velocities and temperatures. A design procedure for spiroid gearing with respect to jamming is proposed.

Study of the Plain Bearings of Modified Wood for Heavy-Loaded Friction Assemblies

The article describes the structure of a self-lubricating plain bearing of modified wood for heavy-loaded friction assemblies and production technology. A method is developed to define the wood’s coefficient of friction on steel and the friction machine MI–1M is upgraded. The sliding friction coefficient changes within 0.06–0.11, depending on the load.

Composite metal-ceramic and metal-polymeric materials for friction assemblies of national civil aircrafts

Experience of using of metal-ceramic and a metal-polymeric material in friction assemblies of aeronautical engineering is generalized. Characteristics and conditions of operation of the sintered friction and antifriction materials are presented. Peculiarities of metal-fluoroplastic tapes of foreign production are considered. Efficiency of using of sintered and metal-polymeric materials in friction assemblies of modern civil aircrafts is shown.

Improving Wear Resistance of Friction Assemblies of Oil-Well Pumps Having Seals from Directionally Reinforced Polymer Composites

Application of polymeric composites in friction assemblies of oil-well pumps is studied. A scheme is proposed for testing specimens from a variety of composites in a steel roller pair, for which the area of the wear spot is taken as the wear resistance criterion. The best results are obtained for specimens from polyamide reinforced 50% with high-molecular-weight synthetic fibres laid perpendicularly to the friction surface.

Research on the Measurement System of Friction Torque for Arc Structure Servo Mechanism

In this paper, in order to realize friction torque measurement and assembly behavior analysis of arc structure servo mechanism (ASSM), a general measurement system applied, meanwhile structural characteristics and performance of the ASSM are analyzed. Based on the fundamental of electrical method, the system is built up by the principle of vertical structure in line. So the system can applied to all kinds of ASSM by replacing the U-shape frame which suits to the target servos. The experiment is carried out on a certain type, the mean value of dynamic friction torque is about 1.00Nm, and the variance of measured data is about 0.01. The results indicate that the measurement system can measure friction torque and its inhomogeneity effectively and can be used in measurement of friction torque on other ASSM.

Metal–polymer tribosystems: Basic recommendations for creating composites

The interconnection of triboelectric, segregation-diffusion and tribochemical processes at metal–polymer contact area have been revealed. A system approach allows the methods for control of friction properties of metal–polymer friction assemblies to be developed. These methods are based on data that describe the effect of the triboelectric field on diffusion processes in metal–polymer tribosystems and the formation of friction transfer film. The formation of the transfer film has been studied by IR-spectroscopy, and element content on the grain boundaries–by Auger-spectroscopy.

ВЗАИМОСВЯЗЬ ГЕРМЕТИЧНОСТИ ПОДШИПНИКОВЫХ УЗЛОВ ТРЕНИЯ С АБРАЗИВНЫМ ИЗНАШИВАНИЕМ ИХ ТРИБОСОПРЯЖЕНИЙ

To ensure wear resistance of all tribo-couplings of a bearing assembly at the expense of the abrasive wear decrease it is necessary the solution of problems connected with the impermeability of their movable joints. In this case by the impermeability we imply a process of sealed “wall” formation which is able to separate reliably volumes with different environments at considerable changes of external factors of environment: temperature, dustiness, aggressiveness and others.
 The contact of two hard surfaces of tribo-coupling of the “shaft-seal” type forms a system of cavities, capillaries of an arbitrary shape and contact patches. Under the action of pressure difference on separate capillaries arise leaks. 
 The depressurization of bearing friction assemblies (leak moment) results in the decrease of wear rate of tribo-coupling of “shaf-tseal” type, but a wear rate of other tribocouplings such as “ringsolid of rolling motion”, for frictionless bearings or “shaft-bushing” for friction bearings increases because of abrasive penetration into a contact area. The penetration of quartz particles (pollutions) through a sealing into a bearing assembly results in the increase of a constant of friction and initiation of abrasive wear in tribocouplings of “ringsolid of rolling motion” and “shaftbushing” types. The wear rate of “ringsolid of rolling motion” and “shaftbushing” couplings depends on the abrasive concentration in lubricant and a leak at the outlet from the bearing assembly. For the wear resistance increase in tribo-couplings of bearing assemblies it is necessary not only to increase the hardness of contact surfaces, ensure optimum roughness, select materials in tribo-couplings, but also to ensure the impermeability and lubricant keeping in a friction area.

Composite Material for Chemical and Petrochemical Equipment Friction Assemblies

Questions are considered for optimizing and intensifying the traditional technology for preparing carbon fluoroplastic composite for piston compressor friction assemblies. A technology is developed for composite preparation and manufacturing methods in each stage, making it possible to create highly efficient and economically substantiated composites for piston compressor assemblies operating under dry friction conditions.

Vibrational density of states and boson peak in two-dimensional frictional granular assemblies

In this paper, the two-dimensional granular assemblies composed of 2048 mono-dispersed frictional disks are simulated by the discrete element method. A set of eigenvalues and corresponding eigenvectors is obtained by diagonalizing the Hessian matrix for each stable configuration. The effects of the friction coefficient of disk on mechanical and geometrical properties of these systems under isotropic confining are studied. Results show that at a fixed pressure, with increasing from 0.001 to 1.0, the crossover frequency *, which separates the Debye scale region from the platform of vibrational density of states, and the boson peak BP gradually shift towards lower frequency, and the intensity of the boson peak D(BP) / BP increases. These results are mainly attributed to the fact that the system becomes more and more disordered with the increase of (i.e., the decrease of the average coordination number), resulting in more excess modes at *. For a better understanding of the different vibration modes of the two-dimensional frictional granular systems, we plot the polarization vector diagrams for different frequencies ( 1 = 0.15, 2 = 1.5 and 3 = 6.0) for configurations with = 0.001 and = 1.0, respectively. Mode analysis results show that the mode at low ( 1.0) has a mixed translational-rotational but translational-dominated character; the mode at intermediate frequency (1.0 4.0) is localized and has a mixed translational-rotational but translational-dominated character; and the mode at high frequency ( 4.0) have a strongly rotational in character. It is worth noting that the low-frequency modes become more localized and the rotational participation fraction also increases as increases, implying that the rotational modes play more important role in the system with higher friction coefficient.

ПЕРСПЕКТИВНЫЕ МАТЕРИАЛЫ ДЛЯ УЗЛОВ ТРЕНИЯ ДЕРЕВОПЕРЕРАБАТЫВАЮЩЕГО ОБОРУДОВАНИЯ

ПЕРСПЕКТИВНЫЕ МАТЕРИАЛЫ ДЛЯ УЗЛОВ ТРЕНИЯ ДЕРЕВОПЕРЕРАБАТЫВАЮЩЕГО ОБОРУДОВАНИЯ

Preparation of Polymer Antifriction Materials for Highly Loaded Oil Pump Friction Assemblies

Technological aspects are developed for preparing graded polymer composite materials for antifriction purposes based on epoxy resin by centrifugal molding, capable of operation without lubricant in oil pump ball friction assemblies.

Developing of Computational Investigation Methodology of Newtonian Fluid in the Crescent-shaped Gap of Turbogenerator Oil-free Bearing

The paper suggests the methodology of computational investigation of fluid and gas flow in the crescent-shaped gap of turbogenerator oil-free bearing on the basis of ANSYS CFX package. Numerical computation data have good convergence with empirical results obtained by other scientists for the same objects. Verification data prove the possibility of computational methodology implementation, at the first stage, in a limited sphere of engineering applications, particularly, when designing cooling systems for eccentric annulus of oil-free friction assemblies.

Influence of Lubricants on Wear and Self-Lubricating Mechanisms of Ni3Al Matrix Self-Lubricating Composites

A research is conducted on the possible beneficial synergistic effects of multiple additives in self-lubricating composites for use in high temperature friction and wear-related mechanical assemblies. Dry sliding tribological tests of Ni3Al matrix self-lubricating composites (NMSCs) on a HT-1000 ball-on-disk high-temperature tribometer are undertaken against Si3N4 at 25-800 °C. The results show that the subsurface microstructures beneath wear scar of NMSCs change with addition of different lubricants, which have great effects on tribological mechanisms and tribological performances. NMSC with addition of MoS2 and Ti3SiC2 exhibits distinct subsurface microstructure beneath wear scar and excellent tribological performance among all samples.

Antifriction Carbon Plastics for Sliding Bearings of Centrifugal Pumps. Part 2*

High-strength antifriction polymeric carbon-fiber-reinforced plastics (carbon plastics) of FUT and UPFS types were developed for facilitating operation of friction assemblies of oil-and-gas and power engineering equipment. The strength and wear resistance of these materials were improved by modifying the chemical composition of the phenolic binder, by electrochemical treatment (ECT) of the carbon fabric surface, by changing the nanostructure of the carbon fibers, and by inserting disperse particles of micromodifiers, i.e., of metals (babbitt, nickel, etc.), into the carbon plastics.

New Method of Friction Assemblies Reliability and Endurance Improvement

Thus a new method of shaft necks processing is suggested for practical application, including application of soft antifriction metal coating, chosen from group: indium, tin, copper, silver, which differs that the coating is applied by electroerosion alloying on the shaft neck surface with discharge energy 0,01-0,03 J in the final operation, or the coating of copper or silver is applied with discharge energy 0,04-0,4 J and subject to post-processing, for example nonabrasive ultrasonic finishing. In such cases the surface layer with the microhardness less that the microhardness of the backing is formed. That promotes the fall of friction assembly normal operation and reduces the possibility of babbit microfractures formation in cubic crystals SnSb, which subsequently become the center of fractions formation in bulk of the layer.

Development of a Technology for the Fabrication of Articles Made of Complex-Modified Polytetrafluoroethylene for Dry Friction Assemblies

The influence of the parameters of ultrasonic compaction on the mechanical and tribological properties of a composite polytetrafluoroethylene-based material is considered. It is shown that through the use of ultrasonic compaction in the course of fabricating complex-modified polytetrafluoroethylene, an increase in the ultimate strength, modulus of elasticity, and wear resistance of the composite are achieved together with a significant reduction in its friction coefficient. The new technology of ultrasonic compaction of a composite material may be used to fabricate plain bearings, sealing elements of shafts and axles of plants and mechanisms, as well as hydraulic engines, and the rods of hydraulic cylinders.

Visualization of characteristics of the contact network between spheres in 3D assembly

Abstract Analysis of geometrical features of 3D granular assemblies poses difficulties in visualization of the effects taking place within the volume of the sample. This work presents the method for visualization of spatial distribution of the contact points in a monodisperse; frictional assembly composed of spheres and generated using three filling methods for a cuboidal or cylindrical container. The visualization is based on the projection of the contact points between particles on a hypothetical sphere followed by their representation on the plane. The proposed method was found to adequately visualize differences in the spatial structure of assemblies generated using various filling methods.

MK-5 frictional material produced with the use of free filled layer technology

Evaluation of operating efficiency of frictional materials made by different manufacturers, allowing to determine the prospect of their use in high-loaded friction assembly, is presented.