Slider Bearing Research Articles

Convergence of (Soft) Elastohydrodynamic Lubrication Simulations of Textured Slider Bearings

We study the convergence of elastohydrodynamic lubrication (EHL) simulations of textured slider bearings. EHL simulations are computationally expensive because the equations that describe the lubricant film pressure and the deformation of the bearing surfaces are coupled and, thus, must be solved simultaneously. Additional simulation requirements, such as maintaining a specific bearing load-carrying capacity or lubricant film thickness, further increase the computational cost because they impose additional constraints or add equations that must converge simultaneously with those that describe the lubricant film pressure and bearing surface deformation. We methodically quantify the convergence of EHL simulations of textured slider bearings as a function of simulation parameters, including different convergence metrics and criteria, but also cavitation models, texture design parameters, and bearing operating parameters. We conclude that the interplay between discretization, the convergence metric, and the convergence criterion must be carefully considered to implement numerical simulations that converge to the correct physical solution. Our analysis also illustrates that a well-designed convergence study can minimize the computational cost.

Simulation and Experimental Research on the Failure of Marine Sliding Bearings

The performance of the marine sliding bearing affects the reliability of marine engineering directly. Nevertheless, sliding bearings are subjected to frictional forces and problems, such as wear and fatigue, that occur after long-term use, which leads to failure. In this study, a sliding bearing friction calculation program is developed using the Fortran language, which calculates the friction force of the bearing under different working conditions. Simultaneously, a component-level sliding bearing tribology testing machine is designed, which predicts the wear failure and explores the wear mechanism for different types of sliding bearings. The model calculation results are in good agreement with the experimental data, which verifies the model’s correctness. Through the wear test, the wear mechanism of the sliding bearing is mainly scratches, and the electroplating layer in the groove is squeezed out of it and attached to the surface of the aluminum alloy to reduce friction. The model and the testing machine provide theoretical guidance for the friction durability of sliding bearings used in marine engineering and guarantee the reliability of marine engineering.

MULTISCALE HYDRODYNAMICS IN INCLINED FIXED PAD THRUST SLIDER BEARING WITH INHOMOGENEOUS SURFACES

For two different and inhomogeneous surfaces, the flow equations for multiscale hydrodynamics involving the boundary layer flows are different from those for two identical and homogenous surfaces. The analysis is presented for the hydrodynamic inclined fixed pad thrust slider bearing with two different and inhomogenous surfaces with low bearing clearances, where both the adsorbed boundary layer flows and the intermediate continuum fluid flow should be considered. Based on the governing equations, the pressure and carried load of the bearing were derived. The calculation results show the performance of the studied bearing different from the bearing with homogeneous surfaces. It was found that by taking the stationary surface in the inlet zone as hydrophobic (or oilphobic) while that in the outlet zone as hydrophilic (or oilphilic), the load-carrying capacity of the bearing can be significantly improved if the bearing clearance is such that the multiscale flow regime occurs and the tilting angle of the bearing is sufficiently small, e.g., no more than 1 × 10<sup>-4</sup> rad.

Розробка системи спрямованого вибору найефективнішої технології підвищення якости бабітових покриттів підшипників ковзання. Ч. 1. Особливості технологій нанесення бабітових покриттів

Розробка системи спрямованого вибору найефективнішої технології підвищення якости бабітових покриттів підшипників ковзання. Ч. 1. Особливості технологій нанесення бабітових покриттів

Thermal and Surface Roughness Effects on Performance Analysis of Slider Bearing via Petrov–Galerkin Finite Element Method

In this study, the performance of slider bearing with impacts of temperature and roughness of surface on 1D longitudinal and transverse roughness type is investigated using the Streamline Upwind Petrov–Galerkin (SUPG)-finite element method (FEM). It is considered that the roughness is stochastic and Gaussian in random distribution. It is also considered that viscosity and density depend upon temperature. The domain’s irregularity caused by surface roughness is changed into a regular domain for numerical computation purposes. To determine the capacity of load-carrying and pressure distribution, the continuity, momentum, modified Reynolds, and energy equations are decoupled and solved by the SUPG-FEM. It can be demonstrated that in the case of the longitudinal model of nonparallel slider bearing, the load-bearing bearing capacity and drag force of friction due to the case i of the combined effects are lower than those attributable to the influence of surface roughness. Nevertheless, the thermal case’s impact on the 1D transverse type capacity of load-carrying capability and drag friction force is below that of the combined and surface roughness impact instances. The reverse is true for parallel slider bearings, however, for a 1D transverse type, the load-carrying ability is not particularly impressive.

The Effect of Rectangular Grooves on the Lubrication Mechanism in an Inclined Slider Bearing

This research aims to study the effect of rectangular grooves on the lubrication mechanism in an inclined slider bearing. Reynolds' equation was used in the theory part to calculate the pressure gradient in a one-dimensional fluid film. The tilted sliding bearing compared the practical results, where the researcher manufactured and developed the device by adding pressure sensors along with the pad. These sensors will give accurate readings because they will read the pressure directly from the bottom of the pads without manometer tubes. Four pads were manufactured, one without grooves and three with rectangular grooves, varying slot widths (3, 5, 8mm), and a depth of 2mm. This study examined various variables: sliding velocities, pad inclination values, and oil temperatures. The conclusions indicated that the flat model is significantly superior to the groove’s models. One significant finding for grooved models is that as the inclination increases, the maximum load capacity approaches the pad's center, allowing grooved models to be used in applications requiring less load and weight. The maximum load-carrying capacity of flat and grooved models was in the film ratio (K) = 2–2.5. In contrast, the load capacity of the flat model was greater than that of the groove model by percentages of 0.5%, 4.27%, and 14.66%, respectively. Moreover, the flat model's coefficient of friction is lower than the coefficient of friction of the groove models, with percentages of 0.38%, 4.63%, and 17.37%, respectively.

STUDY OF RADIAL SLIDE BEARINGS WITH A FLOATING RING CONSIDERING THE PHYSICAL PROPERTIES OF OIL

Radial slide bearings are typically used in turbochargers (among other applications), owing to their simple design and advantages, such as good heat dissipation from the working zone, high stability of operation and low resistance to motion. The current research is both experimental and theoretical. In a state of static equilibrium, the operation of a bearing can be described using a system of five coupled differential equations. The bearing’s operating parameters are related to the type of oil used. Two types of oil, VG46 and VG68, were used for testing. In accordance with the applicable standard, the tolerance of kinematic viscosity of oils is ±10%. The results imply a significant influence of the oil class and viscosity tolerance on the resistance to motion caused by internal friction forces in the oil. In conclusion, it seems advisable that the calculation procedures currently in use should include the slide bearing design optimisation by taking the resistance to motion in the bearing into account.

Toward diagnostics of water-lubricated bearings of naval vessels by vibration analysis

Sliding bearings are mechanical components used for rotor support of high-load mechanical systems. It is assumed that a change in the lubrication regime at a known operational point is a result of an anomaly in the bearing operation such as an increased load, lack of lubricant, and damage to the bearing surface or wear. Detection of this phenomenon will enable diagnostics of the bearing. In this study, we present a novel technique for estimating the transition point between synchronous and asynchronous interactions of the shaft and bearing which is related to the transition between lubrication regimes of a water-lubricated bearing of a marine vessel by vibration analysis. The new technique is demonstrated on an experimental system that reproduces the operation of a water-lubricated bearing. The results demonstrate the ability of using vibration analysis to identify changes in the operating condition of a water-lubricated bearing.

Study on Lubricating Performance of Soft Slider Bearing in Conformal Contact

ABSTRACTIn this paper, the lubricating performance of soft slider bearing in conformal contact is analyzed. Compared with the hard slider, the soft slider will have greater elastic deformation under low pressure. Three kinds of sliders with different elastic modulus are used for comparative study in this paper. The materials of the three sliders are: steel, glass and PMMA. A hydrodynamic lubrication model of conformal contact considering elastic deformation is established according to the theory of fluid lubrication. A program for calculating dynamic pressure lubrication performance of conformal contact considering elastic deformation is developed by using Matlab and Comsol. The influence of different inclination, different speed and different load on hydrodynamic lubrication performance was studied respectively. The results show that under the same conditions, the elastic deformation on the surface of the slider is more conducive to the formation of oil film, and more conducive to the conditions of high load.

Experimental Investigation of the Dynamic Response of a Sliding Bearing System under Different Oil Pressure Levels

A sliding bearing system performs a critical function in a rotating machinery system and provides support for the rotating components. In this paper, a single-rotor experimental rig and a dual-rotor sliding bearing experimental rig were independently established, and the dynamic response of the test systems are investigated. To study the effect of oil pressure levels on the dynamic response of the test systems under the single-rotor system and the dual-rotor system, the vibration response of single-rotor and dual-rotor systems ware analyzed by different oil inlet pressures to study the effect of oil pressure levels on the dynamic response of the test systems under the single-rotor system and the dual-rotor system. Among them, the single rotor system under a large oil pressure system is mostly periodic and more stable. While under different inlet oil pressure conditions applied in the experiments, the dynamic motion of the dual-rotor bearing system is relatively stable in both the subcritical and supercritical speed regions. However, the oil whirl and oil whip of the dual-rotor system were observed at the critical speed, which causes the system into unstable multiperiodic motions. In general, this paper can give some insight into the dynamic response of the sliding bearing system influenced by different oil pressure levels.

Condition Assessment of Railway Bridge Sliding Bearing Using Alternating Vehicle Longitudinal Excitation

The identification of maximum bearing friction is critical to working performance assessment of bridge sliding bearings. The friction-displacement hysteresis model was used for the bearing working performance (BWP) assessment. In this study, the bearing longitudinal displacement (BLD) hysteresis model is established for the sliding bearing system, introducing bearing friction and vehicle longitudinal effect. A novel approach for BWP assessment is presented using alternating vehicle longitudinal excitation. First, bearing friction and vehicle longitudinal effect were introduced to establish the hysteresis model of BLD. Subsequently, the evaluation index and the assessment approach were proposed for BWP assessment using the alternating vehicle longitudinal excitation. Finally, the assessment approach for BWP was applied to a real-world railway bridge. The results show that temperature-displacement relationship model for BWP assessment is unapplicable under significant vehicle longitudinal effects. On the contrary, the BLD induced by alternating vehicle longitudinal excitation can identify the degradation of the BWP when vehicle longitudinal excitation overcomes maximum bearing friction.

A precision core drill for transmission electron microscopy sample preparation produced by 3D printing

A precision core-drilling machine has been designed and constructed almost entirely from 3D printing. The purpose of the drill is to extract 3 mm diameter discs from thin slices of mainly hard brittle materials for analysis in a transmission electron microscope. Novel methods of producing a slide bearing and shaft couplings in 3D printed components have been developed. Design principles and material selection are discussed, and the drill is evaluated by preparing samples from silicon and aluminium. The device can be self-made by any laboratory with a 3D printer, can be recycled when no longer required and can help labs reach their sustainable development goals.

Overview of Friction and Wear Performance of Sliding Bearings

Sliding bearings are critical components of the internal combustion engine. Friction and wear occur in the contact area between the shaft and the bearing. Significant wear can occur in poor working conditions or after a long service time, leading to the failure of the sliding bearing and affecting the reliability of the machinery. It is essential to investigate the wear performance of sliding bearings, understand their wear mechanism, predict their service life, and select wear-resistant materials and surface treatments. This paper reviews the current status and prospects of sliding bearing wear research, focusing on the classification of sliding bearing wear tests, wear testing machines, wear test research, wear prediction models, and future research prospects.

Experimental Investigation of the Performance of SBR and RSS Materials as a Sliding Bearing Element

Conventional bearing systems and materials, which are important components of machine elements, have often failed to fulfil requirements, especially in places where sealing is required. In such cases, sliding bearings with PTFE- and NBR-based polymer and elastomer materials operating in water or oil are preferred. In this study, the performance of two alternative rubber-based materials, synthetic styrene butadiene rubber (SBR) and natural rubber smoked sheet (RSS), as a sliding bearing was experimentally investigated in terms of frictional resistance using pin-on-disc and pin-on-cylinder devices. In the study, very low friction forces emerged at low sliding speeds compared to PTFE and NR operating in water. The friction force values and friction coefficients obtained are presented in diagrams and tables.

Multiscale Modeling and Simulation of Hydrodynamic Inclined Fixed Pad Thrust Slider Bearing

Numerical calculations were made for the multiscale hydrodynamic inclined fixed pad thrust slider bearing where the nanoscale non-continuum adsorbed layer flow and the intermediate continuum fluid flow simultaneously occur. They were compared with the results calculated from the analytically derived pressure formulas in the earlier study for the same bearing, which are essentially approximate. It was found that when the surface separation on the exit of the bearing is no less than 13[Formula: see text]nm, the analytically derived pressure formulas are valid for the studied multiscale hydrodynamic bearing for the weak, medium and strong fluid-bearing surface interactions; otherwise, the numerical approach is mandatory for calculating the hydrodynamic pressures in the bearing.

Influence of Pressure Changes on the Viscosity of Lubricating Oil in CFD Simulations of Conical Bearing Hydrodynamic Lubrication

Abstract The aim of this study is to consider the effect of pressure on the viscosity of lubricating oil in the adopted model of hydrodynamic lubrication and on the calculated flow parameters and operating parameters of a conical slide bearing. The numerical analysis consisted in solving the Reynolds type equation for the process of stationary hydrodynamic lubrication.

Analysis for Hydrodynamic Wedge-Platform Thrust Slider Bearing with Ultralow Surface Separation

For the case of ultralow surface separation, in a hydrodynamic wedge-platform thrust slider bearing, the outlet zone and a portion of the inlet zone are in boundary lubrication, while most of the inlet zone is in the multiscale lubrication contributed by both the adsorbed boundary layer and the intermediate continuum fluid film. The present paper first presents the mathematical derivations for the generated pressure and carried load of this bearing based on the governing equation for boundary lubrication and the multiscale flow equation. Then, the full numerical calculation is carried out to verify the analytical derivations. It was found that the mathematical derivations normally have considerable errors when calculating the hydrodynamic pressure distribution in the bearing, owing to introducing the equivalent parameter λ bf , e which is constant in the inlet zone; however they can be used to calculate the carried load of the bearing when the surface separation in the outlet zone is sufficiently high. The study suggests the necessity of the numerical calculation of the hydrodynamic pressure and even the carried load of this bearing. It is also shown that owing to the fluid-bearing surface interaction, the pressure and carried load of this bearing are significantly greater than those calculated from the classical hydrodynamic theory.

Manufacturing Technology of Sliding Bearings from Ferro-Graphite Compositions

Introduction. The development of modern technology imposes increasingly stringent requirements on materials operating under conditions of high pressures, speeds, deformations and aggressive media. The use of powder metallurgy methods in the creation of new materials makes it possible to provide a rational combination of production technology, structural and performance characteristics. Powder steels used in mechanical engineering are of great interest among the materials obtained by powder metallurgy. The article explores the possibility of manufacturing porous bearings made of iron powder for fan motors of domestic air conditioners instead of porous bearings made of bronze graphite.Problem Statement. To ensure long-term operation of fan motors from metal powders, it is necessary to create porous bearings without alloying additives with the required mechanical properties. This requires a series of experimental work to determine the dependences of mechanical and technological properties on the sintering temperature, compacting pressure and the porosity of samples.Theoretical Part. As a theoretical description, the use of a mold with an additional draining gap, which provides high bearing density at low compacting pressure, is analyzed. The effect of compacting pressure on the strength of sliding bearings under mechanical deformations depending on the sintering temperature is also considered.Conclusions. It was established in the work that during the sintering of sliding bearings at a temperature of 800-1100°C, a significant charge carburization occurs due to the decomposition of zinc stearate in closed pores. As a result, a ferritepearlite structure is formed, due to which the bearings are well calibrated and have high wear resistance when paired with a steel shaft. Optimum sintering modes and compacting pressures were selected, which showed high reliability and durability of the products obtained from pure iron powder.

Study on the influence of interfacial slip on the lubrication performance of a step slider bearing

Experimental and theoretical studies have been completed in this paper to investigate the interface effect in the lubrication performance of a step slider bearing. Oleophobic fluorine-containing diamond-like carbon (F-DLC) coatings were prepared on the step slider to provide low affinity to lubrication films. With an optical slider bearing test rig, it is revealed that the F-DLC coating presents an increase in the film thickness/load-carrying capacity and a decrease in the coefficient of friction (COF), which is quite different from the common idea that both the load-carrying capacity and the COF are reduced at the same time. Contact angles measurement on the step slider shows that the affinity to the lubricant of the inlet step surface is lower than that of the outlet land, which can be attributed to the rougher surface of the step surface by the laser ablation. Theoretical analyses show that various interfacial slip velocities on the inlet step and the outlet land can generate different change in the load-carrying capacity and the COF. When the step surface presents lower interfacial slip velocity of the film than the land surface, increase in load-carrying capacity and decrease in the COF can be theoretically found to support the experiments finds.

Simulation of the Thermal Process in a Polymeric Slide Bearing with a Reciprocally Moving Shaft

Simulation of the Thermal Process in a Polymeric Slide Bearing with a Reciprocally Moving Shaft