Slider Bearing Research Articles

Wear Life Prediction of Sliding Bearings Based on Multitype Monitoring Data of Bridges

Wear Life Prediction of Sliding Bearings Based on Multitype Monitoring Data of Bridges

Numerical Analysis of Dynamic Characteristics of Spherical Hybrid Sliding Bearing Based on Orthogonal Experiment

Numerical Analysis of Dynamic Characteristics of Spherical Hybrid Sliding Bearing Based on Orthogonal Experiment

Effect of Double Porous Layer on Rough Step Slider Bearing Lubricated with Couple Stress Fluid

Effect of Double Porous Layer on Rough Step Slider Bearing Lubricated with Couple Stress Fluid

Performance of rough secant slider bearing lubricated with couple stress fluid in the presence of magnetic field

The effect of surface roughness, magnetic field, and couple stress on the performance of secant slider bearing is studied in this paper. The effectiveness of the bearing is assessed by using a couple stress liquid as the lubricant in the process. Because of microstructural impacts, couple stress fluids have distinctive rheological characteristics. These features have the potential to make a major impact on the bearing’s performance. The novel aspect of this study is that the roughness of the secant slider is taken into consideration. The modified Reynolds equation is derived using Christensen’s stochastic theory for roughness. Here, both transverse and longitudinal roughness patterns are considered. The analytical solutions are obtained for steady-state pressure, load-carrying capacity, film stiffness, and damping coefficient. The results are presented for various parameters through graphs and tables. The combined effect of the magnetic field and couple stress is significant on bearing characteristics. It is noticed that the bearing features increase with the longitudinal roughness parameter, and the reverse phenomenon is observed with the transverse roughness parameter. When a transverse roughness pattern is assumed on a secant slider bearing, characteristics like pressure, load, stiffness of the film, and damping coefficient increase significantly.

Study of the Performance of a Thrust Sliding Bearing in Startup and Rundown Regimes

Study of the Performance of a Thrust Sliding Bearing in Startup and Rundown Regimes

Increasing the efficiency of machines and mechanisms of the agro-industrial complex using sliding bearings with curvilinear generators of the internal cylindrical surface

Sliding bearings with curved internal cylindrical surfaces have great potential and can play an important role in the repair and restoration of mechanisms of the agro-industrial complex. Since their use is becoming more and more common, there is a need to improve the design of such bearings to ensure their quality use and avoid errors in research on this issue, in addition, achieving better results in this area require significant financial investments to improve the efficiency of such mechanisms. The main goal of this work is to provide recommendations aimed at eliminating errors in the processes of improving and improving the quality of sliding bearings, as well as analyzing the functioning of machines used in the agro-industrial complex. An analytical method, a classification method, a functional method, a statistical method, and a synthesis method were used. In the course of the research, the peculiarities and differences of sliding bearings with curvilinear generators of the internal cylindrical surface were noted, errors and their causes, which are allowed during the improvement of agro-industrial mechanisms that ensure the development of the agricultural industry, were analyzed. It is important to analyze the functioning of these mechanisms in order to assess their effectiveness, development and complexity of work during the production of agricultural products. The issue of evaluating the performance of sliding bearings of this type, the expediency of using this element, their limitations during the process, the impact of limitations on the result was considered, and recommendations were proposed that would contribute to an effective mechanism for regulating the issue. It was determined that the use of sliding bearings of this type, in the process of restoring agro-industrial mechanisms, will ensure a significant increase in the productivity of these machines. The practical value of this work lies in the possibility of applying the obtained results to eliminate errors in the development and improvement of the mechanisms of the agro-industrial complex, studying the reliability of the use of sliding bearings in general, taking into account various factors, will provide a basis for recommendations on the appropriate use of these bearings

Shaking table tests of a full-scale base-isolated flat-bottom steel silo equipped with curved surface slider bearings

This paper presents a series of shaking table tests on a full-scale flat-bottom steel silo filled with soft wheat, under isolated-base conditions. The tested specimen is a 3.64 m-diameter 5.50 m-height corrugated-wall cylindrical silo, representing the smallest manufactured silo available in the catalogue of an Italian commercial silo provider. Curved Surface Slider isolators were introduced between the shaking table and the reinforced-concrete plate, on which the silo was mounted, to realize the isolated configuration where the main results have been investigated and compared with other results for the same silo specimen under fixed-base conditions. A detailed description of the silo components, the filling bulk material properties as well as the test setup is provided, including the full testing protocol. Multiple sensors were used to monitor the dynamic response of the filled silo system, including accelerometers, pressure cells, LVDT displacement transducers. Numerous unidirectional dynamic tests were conducted consisting of random signals, sinusoidal inputs, pulse-like inputs, and both artificial and real earthquake records. The results were processed to evaluate the performance of the isolators and their effectiveness on the silo response in terms of measured accelerations and dynamic overpressures. The efficiency of the isolation on the reduction of both acceleration amplifications over the silo wall height as well as the captured dynamic overpressures were detected in the range 30%–80% depending on the input type and magnitude.

Knudsen Maximum Effect in Micro-Scale Gas Lubrication

Abstract Micro-scale gas lubrication has been studied for several decades, with extensive research on non-equilibrium flow effects like velocity slip and thermal creep. However, the Knudsen maximum effect in micro-scale gas lubrication has not been reported yet. To address this, we analyzed the load capacity characteristics of slider bearings with ultra-thin film gas lubrication equations derived from the linearized Boltzmann-Bathnagar–Gross–Krook model equation (Fukui–Kaneko lubrication model) under the condition of constant bearing number. Our study reveals that there exists a maximum value of load capacity for slider bearings when the reference Knudsen number is about unity. This happens because the dimensionless mass flowrate of micro-scale gas flows has a minimum value when the reference Knudsen number approaches unity. Understanding the Knudsen maximum effect is crucial when designing micro-nano devices related to gas lubrication, as it implies that there exists an optimum clearance for maximum load capacity.

Analysis of thermal and surface roughness effects of slider bearing in the case of turbulent lubricant flow using finite element method

Analysis of thermal and surface roughness effects of slider bearing in the case of turbulent lubricant flow using finite element method

Influence of Geometrical Shape on the Lubrication Performance of Partially Micro-Grooved Gas-Lubricated Parallel Slider Bearings

The influence of grooving parameters and micro-groove cross-section shape on the lubrication performance of partially micro-grooved gas-lubricated parallel slider bearings is investigated in the present study. The solution procedure for the multi-grid finite element method is that the algebraic equations formed by the finite element method are in turn smoothed by the interpolation from the coarse grid to the fine grid and the restriction from the fine grid to the coarse grid. By adopting the multi-grid finite element method, the pressure distribution of partially micro-grooved gas-lubricated parallel slider bearings is obtained. The grooving parameters are optimized to obtain the maximum average pressure for different micro-groove cross-section shapes. The results show that the orientation angle of the micro-grooves, depth of the micro-grooves, width of the micro-grooves, area density of the micro-grooves, micro-grooved fraction, and cross-section shape of the micro-grooves have an important influence on the hydrodynamic pressure of partially micro-grooved gas-lubricated parallel slider bearings. The results of this study demonstrate that the lubrication performance of partially micro-grooved gas-lubricated parallel slider bearings can be obviously enhanced by adopting the appropriate grooving parameters and micro-groove cross-shape. The results of this study is beneficial for the design of partially micro-grooved gas-lubricated parallel slider bearings.

Thermal Diagnostics of Friction in Self-Lubricating Sliding Bearings with Swinging Movement of the Shaft

Thermal Diagnostics of Friction in Self-Lubricating Sliding Bearings with Swinging Movement of the Shaft

Effect of sliding speed on the thermohydrodynamic performance of partially slip‐textured slider bearings

AbstractThe present study evaluates the combined use of micro‐textures and ‘wettability gradient’ on the thermohydrodynamic performance of inclined slider bearings. Mass conserving Elrod cavitation model with slip boundary condition has been used to investigate the dimensionless static performance parameters at different convergence ratios and sliding speeds. The most effective location of the wettability gradient and textures has been considered in the present work. It has been observed that with the increase in sliding speed, the load carrying capacity, friction force and volumetric inflow rate of the slip‐textured bearings were improved. The improvements were more pronounced at smaller convergence ratios. Moreover, the slip‐textured bearings exhibited significant improvement in the average pressure and temperature of the lubricant. However, at higher sliding speeds, a substantial increase in friction force and average lubricant temperature was noticed. The square textured slip bearing exhibited maximum improvements towards various performance parameters of the three considered texture shapes.

Energy-Conserved Hydrodynamic Lubricated Components with Wall Slippage

The hydrodynamic thrust slider and journal bearings as well as hydrodynamic lubricated gears with the merit of energy conservation by the wall slippage are reviewed. The principle for designing these hydrodynamic contacts is to artificially set the wall slippage on the stationary surface in the hydrodynamic inlet zone. To design the wall slippage on the moving surface in the hydrodynamic outlet zone can also give additional benefits. The technical merits of these mechanical components are the improved load-carrying capacity and the lowed friction coefficient, i.e., the energy conservation due to the wall slippage. Owing to the designed wall slippage, the carried load of the hydrodynamic step bearing can be increased by 200%~400% while its friction coefficient can be reduced by 50%~85%, and the load-carrying capacity of the hydrodynamic journal bearing can be increased by nearly 100% while at the same time, its friction coefficient can be reduced by more than 60%. For hydrodynamic lubricated gear contacts, by covering ultrahydrophobic or oilphobic coatings on the slower moving surface, the friction coefficient can be approaching to vanishing and the contact load-carrying capacity can be increased very significantly for large slide-roll ratios under medium or heavy loads.

A Study of Finite Hydrodynamic Slider Bearings Lubricated With Ferrofluids

A Study of Finite Hydrodynamic Slider Bearings Lubricated With Ferrofluids

The Regularity of Increasing the Wear Resistance of a Modified Radial Slide Bearing

The Regularity of Increasing the Wear Resistance of a Modified Radial Slide Bearing

A two-scale methodology on modelling surface topography by homogenization technique

In the work, a novel two-scale computational approach aiming to provide the homogenized behavior informed by microscale computations is developed for hydrodynamically lubricated slider bearing. A derivative formulation with respect to main lubricated parameters is derived to calculate the fluid pressure at the macroscopic domain. Partial derivative terms included in this formulation are calculated by employing the linearization method presented, where flow fluxes obtained at the microscopic domain are averaged using homogenization technique. On the basis of pressure shift and mass conservation principle, the near-periodic boundary conditions are modelled for exactly describing the fluid behavior at the microscopic domain. A series of numerical simulations are implemented for evaluating the impacts of the topography shape, the topography amplitude, and the topography wavelength on bearing characteristics.

A numerical algorithm to model wall slip and cavitation in two-dimensional hydrodynamically lubricated contacts

Hydrodynamic lubrication takes a fundamental role in mechanical systems to reduce energy losses and prevent mechanical breakdown. The analytic instrument usually adopted to describe hydrodynamic lubrication is the Reynolds equation, which in its simplest statement for monophase lubricants and with assuming no fluid slip at the walls, is a linear equation in the hydrodynamic pressure. However, this classical linear Reynolds equation cannot reflect all the lubricant characteristics in engineered surfaces (e.g. superhydro(oleo)phobic surfaces and textured surfaces). In these cases, the effect of two critical factors, such as wall slip and cavitation, need to be considered, introducing non-linearities in the system. In order to tackle this issue, a modified two-dimensional Reynolds equation is introduced, able to capture both the cavitation presence, via a complementary mass-conserving model, and wall slippage, starting from the multi-linearity description introduced by Ma et al. (2007). In addition, an alternative model for the slippage at the wall is proposed by modifying the multi-linearity wall slip model to improve accuracy and computational cost. In this new model, the possible slip directions are limited to three, separated by equal angles, with the slip occurring only along the first direction, and the other directions, then, used to iteratively adjust the direction of slippage, until a suitable convergence criterion is satisfied. The proposed mathematical model is validated versus results available in literature with tests performed on (i) journal bearings, (ii) slider bearings, (iii) squeeze dampers, and (iv) surface textured bearings. By conducting these tests, the proposed alternative wall slip model is proved to be up to one order of magnitude more computational efficient than the original multi-linearity wall slip model.

Comparative Wear Test of Journal Sliding Bearings with Sintered Bronze and Babbitt Alloy Bushes Lubricated by Environmentally Acceptable/Adapted Lubricants (EAL)

A growing awareness of the negative effects of mineral oils on the natural environment has resulted in the introduction of new regulations related to environmental protection. One of these regulations requires the use of environmentally acceptable/adapted lubricants (EAL) to lubricate marine main shaft bearings, in place of the mineral lubricating oils that have been used for decades. Classification Societies, which supervise the technical condition of ships, record a certain number of failures each year of heavy loaded stern tube bearings lubricated with modern, environmentally friendly lubricants. The reason often given for such failures is that the operating parameters of EAL lubricants are worse than those of mineral oils. The aim of the experimental research reported here was to compare the operating parameters and wear of EAL lubricated journal sliding bearings. For this purpose, two classic mineral lubricating oils and a group of four alternative lubricants from the EAL group were selected. The tests carried out for two types of bearing bushes—sintered bronze and Babbitt—did not show significant differences in terms of operating parameters or journal and bush wear for the entire group of tested lubricants.

Some rheological properties of plastic greases by Carreau-Yasuda model

Various greases are often used for lubrication of various roller bearing and more seldom for slide bearings operating under rather lower speed values, when the mixed or boundary friction occur, for example, during operation in the start-stop regime. Three various commercial greases were tested, differing in the value of the kinematic viscosity of the base oils used in them, measured at temperature 40 °C and 100 °C, and the resulting different dropping point temperature. The rheological properties of such greases have been determined using the rotary rheometer. Based on the resulted dependencies of the apparent viscosity on the shear rate the parameters of the Carreau-Yasuda rheological model chosen, have been estimated. The prediction of rheological parameters for three plastic greases studied obtained with particularly good accuracy. Among the tested greases, the grease with the highest drop point temperature turned out to be a mechanically stable grease. The differences in parameters values could be affected by differences in the compounds of the greases studied.

Evaluation for Crack Defects of Self-Lubricating Sliding Bearings Coating Based on Terahertz Non-Destructive Testing

In this study, a non-destructive testing method for crack defects of self-lubricating sliding bearing coating based on terahertz time-domain spectroscopy was proposed. The self-lubricating coating materials were revealed to have good penetration and characteristic response in the terahertz band through experiments. To solve the problem of difficulty in signal feature extraction caused by overlap, the broad learning system was used to classify and predict time-domain signals of crack defects. The identification accuracy for crack defects is 96.08%, and the mean relative errors of prediction for interface and internal cracks (5 to 95 μm in size) are 4.16% and 3.40%, respectively. The method proved the applicability for qualitative and quantitative evaluation in crack defects, which is considered a new idea for the non-destructive testing of self-lubricating coating.