Bearing Performance Parameters Research Articles

Combined Effect of Surface Irregularities and Applied Voltage on the Behavior of Hole-Entry Spherical Hybrid Journal Bearings Lubricated with an Electro-Rheological Fluid

Abstract Surface irregularities substantially affect the performance of tribological systems. The influence of three-dimensional surface irregularities has been investigated on the behavior of hole-entry spherical hybrid journal bearings. Recently, smart fluids have been employed in several applications to improve their performance. The interactive effect of electro-rheological (ER) fluid and surface irregularities have also been studied. The modified Reynolds equation and restrictor flow equation have been solved using the finite element technique with appropriate boundary conditions. The results show that consideration of surface irregularities on bearing surface enhances bearing stability. Spherical hybrid journal bearings lubricated by ER fluid increase minimum fluid film thickness and minimize the possibility of metal-to-metal contact. It is found that the combined effect of surface irregularities and ER fluid significantly improved the bearing performance parameters than individual behavior. The bearing designer is anticipated to benefit from the current model.

Alleviating thermal challenges in hydrodynamic bearings: A novel approach through thrust bearing pads with embedded cooling circuitry and deep recess

At high speeds minimization of operating temperature is the critical design objective in hydrodynamic thrust bearings. During the high speed operations of heavy duty machines high temperatures are generated in thrust bearings due to vigorous viscous shearing of lubricant oil film. Under such circumstances thermal effects gain critical importance. Consequences of thermal effects include pad deformation, increased wear, material degradation etc. in hydrodynamic bearings. This research explores a pioneering approach to mitigate thermal challenges by integrating deep recesses and cooling circuitry in thrust bearing pads. The integrated design facilitates enhanced heat dissipation and load carrying capacity along with optimized lubrication process. In this study CFD (CFX) simulation code is used to numerically evaluate the effect of hybrid bearing configuration (conventional thrust pad equipped with deep recess and embedded cooling circuitry) on the performance parameters of thrust bearing. The simulation results confirm an appreciable decrease in maximum pad temperature and thermal pad deformation. The maximum pad temperature decreased from 85℃ to 71℃. Similarly value of thermal pad deformation decreased from 36 µm to 24 µm. The outcomes hold promise for enhancing the thermal performance of existing machinery and inspiring the development of next-generation thrust bearing systems, marking a transformative advancement in the field of mechanical engineering.

AI techniques for evaluating misaligned journal bearing performance: An approach beyond the Sommerfeld number

This paper presents two novel artificial intelligence-based approaches for evaluating the performance of heavily loaded marine journal bearings including shaft misalignment. Traditionally, the Sommerfeld number has been used as a key parameter to evaluate the performance similarity between different bearings. However, this method has limitations, particularly when dealing with complex elastic geometries, heavily loaded journal bearings and shaft misalignment. The first proposed approach leverages neural networks to analyze key bearing performance parameters and provide a more accurate and comprehensive assessment of bearing performance similarity, including additional parameters beyond the Sommerfeld number limitations. The second method utilizes artificial intelligence convolutional networks to assess the bearing similarity based on their simulated pressure profiles under isoviscous and isothermal hydrodynamic lubrication regime. The effectiveness of the proposed methods is demonstrated and compared to the traditional Sommerfeld number method, discussing various potential applications and extensions of this concept.

The Effects Analysis of Contact Stiffness of Double-Row Tapered Roller Bearing under Composite Loads

Double-row tapered roller bearings have been widely used in various equipment recently due to their compact structure and ability to withstand large loads. The dynamic stiffness is composed of contact stiffness, oil film stiffness and support stiffness, and the contact stiffness has the most significant influence on the dynamic performance of the bearing. There are few studies on the contact stiffness of double-row tapered roller bearings. Firstly, the contact mechanics calculation model of double-row tapered roller bearing under composite loads has been established. On this basis, the influence of load distribution of double-row tapered roller bearing is analyzed, and the calculation model of contact stiffness of double-row tapered roller bearing is obtained according to the relationship between overall stiffness and local stiffness of bearing. Based on the established stiffness model, the influence of different working conditions on the contact stiffness of the bearing is simulated and analyzed, and the effects of radial load, axial load, bending moment load, speed, preload, and deflection angle on the contact stiffness of double row tapered roller bearings have been revealed. Finally, by comparing the results with Adams simulation results, the error is within 8%, which verifies the validity and accuracy of the proposed model and method. The research content of this paper provides theoretical support for the design of double-row tapered roller bearings and the identification of bearing performance parameters under complex loads.

A transfer learning based artificial neural network in geometrical design of textured surfaces for tribological applications

This study aims at introducing the potential to utilise transfer learning methods in the training of artificial neural networks for tribological applications. Artificially enhanced surfaces through surface texturing, as an example, are investigated under hydrodynamic regime of lubrication. The performance of these surface features is assessed in terms of load carrying capacity and friction. A large performance dataset including bearing load carrying capacity and friction is initially obtained for a specific category of textures with rectangular cross-sectional profile through analytical methods. The produced bearing performance are used to train a neural network. This neural network was then trained further by a minimal set of performance measure data from an intended category of textures with triangular cross-sectional profiles. It is shown that the resulting neural network performs with acceptable level of confidence for those intended texture profiles when trained with such relatively low number of performance data points. The results indicate that fast analytical methods can potentially produce a large volume of training datasets, which effectively allows for use of relatively lower number of training data sets from the intended category, where creating data for trainings can be more complex or time consuming. Use of transfer learning method in tribological applications and use of bearing performance parameters, as opposed to bearing design parameters, for training the neural networks are the major novel contributions of this study, which has not hitherto been reported elsewhere.

A study of misaligned compliant journal bearings lubricated by non-Newtonian fluid considering surface roughness

To study the static behavior of misaligned journal bearings under heavy loads using a non-Newtonian lubricant (pseudoplastic fluid, the flow behavior obeys a power-law relationship). And the generalized average Reynolds equation for rough journal bearing under pseudoplastic lubricant flow is derived. The establishment method of the model equation adopts the average flow method of Patir and Cheng. The numerical solution of bearing performance parameters applies the finite difference method and the successive over-relaxation method. And surface roughness can partially offset the effects of liner elastic deformation and lubricant shear thinning. The generalized average Reynolds equation derived in this paper is not only used in the research of hydrodynamic lubrication but also can be used in the research of mixed lubrication.

Dynamic performance and stability characteristics of a multi pad externally adjustable fluid film bearing

ABSTRACT Due to the recent advances in the development of smart rotating machineries, there is a high demand for automated support bearings with efficient integrated control systems. Existing research studies have indicated that high-end performance can be attained from automated bearings through effective control and modification of the bearing performance parameters. In this study, an innovative journal bearing geometry with multi-control operations is presented. The four controllable bearing pads enclosed in the bearing casing have a novel feature to translate radially and undergo controlled tilt motions. The multi-control bearing system with radial and tilt pad motions will significantly influence the stability responses of the rotorsystem, which is theoretically analysed in this study. To predict the variation in film thickness for varied pad adjustments, a modified film thickness equation is incorporated in the linearised perturbed model for dynamic analysis. A notable variation in dynamic coefficients and stability parameters are observed for negative radial adjustment and tilt angles. Results indicate that negatively adjusted radial and pad tilt motion can generate improved stability margins at higher eccentricities. Data generated on stability margins at specific pad adjustments will be helpful while developing the control system for the actuation mechanism in the experimental setup.

Design and analysis of 5 kW helium turbine for EAST cryoplant

The helium turbine is an important core component in the refrigerator, which provides support and guarantee for the stable operation of the cryogenic system. This paper refers to the parameters of one of the four helium turbines in EAST, designs a 5 kW helium turbine. The overall structure of the turbine has been described, and the design and analysis of the impeller and bearing have been carried out. Through CFD analysis, the internal pressure and temperature change law of the flow is analyzed. The variable-condition operating characteristics of the turbine are predicted, and it is found that the turbine can maintain efficient operation within a wide range of mass flow changes. The bearing performance is calculated by solving the Reynolds equation. After determining the optimal bearing clearance 28 μm based on the principle of maximum stiffness, bearing performance parameters of load capacity and stiffness can be further calculated.

Effect of texture geometry on the performance of noncircular aerodynamic journal bearings

Today, considerable uses of aerodynamic journal bearings have attracted the attention of many researchers in the field of tribology. Therefore, the theoretical and experimental analysis of their performance has been the subject of many researches. Growing application of the gas journal bearings is due to their capability in various engineering fields such as instrumentation and high-speed machines like spindles, small-scale turbomachines, and precision gyroscopes, dental milling machines, and many other rotor-bearing systems. Upgrading the performance of gas bearings by changing their geometry or using new compressible lubricants has always been one of the suggestions proposed by the tribology researchers. Recently, the development of new technologies such as laser milling and lithography increased the possibility of creating textured surfaces as a way to improve the performance of journal bearings. So, in this study, the effects of texture geometry on the steady-state performance of two-lobe noncircular aerodynamic journal bearings are presented. For this purpose, the governing Reynolds equation of hydrodynamic gas lubrication is analyzed by finite element method according to the changes of the lubricant film thickness in presence of the cubical, cylindrical, and ellipsoidal surface textures. Results show that the creation of textures on the lower lobe compared to the upper lobe or the whole surface is more effective on the performance of two-lobe aerodynamic bearings. Also, increasing both the dimple depth and the amount of bearings noncircularity, especially at shallow texture depth, cause more significant changes in the lubricant film pressure distribution and the bearing performance parameters such as load-carrying capacity, attitude angle, and frictional power loss. Further, it is obvious that the creation of cubical, cylindrical and ellipsoidal textures especially at shallow depth with an increase in the noncircularity of bearings’ geometry have a higher impact on the steady-state performance of the studied rotor-bearing system, respectively.

Computational Efficiency Improvement of Dimple Textured Hydrodynamic Journal Bearing Using Progressive Mesh Densification Method

Abstract There is a considerable amount of study carried out on textured hydrodynamic bearings. The numerical solution of textured bearings is a matter of concern for the researchers. There are several methods used to estimate the performance parameters of textured bearings. However, progressive mesh densification (PMD) method is not yet used for textured bearings while it has been used for mixed elastohydrodynamic lubrication (EHL) and thermo-EHL problems. In the present analysis, the PMD method is implemented to estimate the performance parameters of the textured journal bearing. It is compared with the multigrid and the fixed mesh methods and found to be very effective in improving computational efficiency.

Performance of finite bearing under the combined influence of turbulent and non-Newtonian lubrication

The current numerical investigation is used to predict the dynamic performance of finite bearing considering the combined influence of turbulence regime and non-Newtonian flow. With appropriate assumptions, the Navier–Stokes and continuity equation have been revised by the linear turbulence and non-Newtonian fluid model together. The clearance space of the finite bearing has been determined by the finite element method adopting Galerkin’s procedure and robust iteration technique. The cylindrical coordinate forms of momentum and continuity equations are used for the flow field of the finite bearing assuming the turbulent regime and non-Newtonian lubricant. Dynamic performance parameters of a finite bearing have been computed regarding direct and cross-coupled fluid-film coefficients, equivalent stiffness coefficient, whirl ratio, and critical mass at different eccentricity ratios for distinct values of Reynolds numbers preferably up to 13,300 and varied values of non-linear factor of the non-Newtonian fluid model. The obtained results revealed the performance enhancement in the combined regime as compared to pure turbulence and non-Newtonian flow conditions. The stability of finite bearing is significantly improved under the proposed severe flow regime.

Rotor-dynamic performance of porous hydrostatic thrust bearing operating under magnetic field

Purpose The porous bearings are commonly used in slider thrust bearings owing to their self-lubricating properties and cost effectiveness as compared to conventional hydrodynamic bearings. The purpose of this paper is to numerically investigate usefulness of porous layer in hydrostatic thrust bearing operating with magnetic fluid. The effect of magnetic field and permeability has been analysed on steady-state (film pressure, film reaction and lubricant flow rate) and rotor-dynamic (stiffness and damping) parameters of bearing. Design/methodology/approach Finite element approach is used to obtain numerical solution of flow governing equations (Magneto-hydrodynamics Reynolds equation, Darcy law and capillary equation) for computing abovementioned performance indices. Finite element method formulation converts elliptical Reynolds equation into set of algebraic equation that are solved using Gauss–Seidel method. Findings It has been reported that porosity has limited but adverse effects on performance parameters of bearing. The adverse effects of porosity can be minimized by using a circular pocket for achieving better steady-state response and an annular/elliptical pocket, for having better rotor-dynamic response. The use of magnetic fluid is found to be substantially enhancing the fluid film reaction (53%) and damping parameters (55%). Practical implications The present work recommends use of circular pocket for achieving better steady-state performance indices. However, annular and elliptical pockets should be preferred, when design criteria for the bearing are better rotor-dynamic performance. Originality/value This study deals with influence of magnetic fluid, porosity and pocket shape on rotor-dynamic performance of externally pressurized thrust bearing. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0289/

Influence of geometric imperfection of journal on the performance of porous hybrid journal bearing under turbulent condition

The present work deals with numerical investigation into geometric imperfection (bellmouth, undulation and barrel shape) of the journal on performance of a porous hybrid journal bearing system (PHJBs) operating under turbulent flow condition. The Reynolds equation governing the flow of lubricant in the bearing clearance space is modified by using the turbulent lubrication theory proposed by Constantinescu’s. The bearing performance parameters are numerically computed using FEM. The effects of geometric irregularities, turbulent flow condition, and permeability parameters have been investigated on the performance of PHJBs. The theoretically obtained results indicates that the combined effect of turbulent flow condition and geometric imperfection offers enhanced values of [Formula: see text] and rotor dynamic coefficients (stiffness and damping coefficients).

Static thermal performance evaluation of elliptical journal bearings with nanolubricants

Journal bearings of different configurations have been extensively used in turbomachinery and power generating equipments. Although circular bearings have simplest configuration and commonly used journal bearings, non-circular bearings such as multi-lobe and elliptical bearings have an added advantage of lower lubrication film temperature alongwith stable operation. In this study, static thermal performance of pure elliptical bearing lubricated with nanoparticles based mineral oils has been studied at different eccentricity ratios and bearing speeds. Two types of nanoparticles, namely, CuO and TiO2 with 0.5, 1.0 and 2.0 wt.% concentrations have been separately added in three different viscosity grades of oils. The effect of nanoparticles on thermo-physical properties of oil was considered to compute bearing performance parameters (pressure distribution, load capacity, oil temperature and power losses). Bearing model was generated by taking into account the modified Krieger Dougherty method to determine viscosity at different combinations of oils and nanoparticles. The findings indicate the increase in maximum pressure and load capacity with addition of nanoparticles and this increase was more pronounced at higher concentrations of nanoparticles and at higher viscosity grade oils. Load capacity was found to be increased by 14.24% and 9.21% with 2 wt% concentration of TiO2 and CuO nanoparticles respectively in base oil (AW68) at eccentricity ratio of 0.7. An increase in load capacity with nanolubricants was achieved without an appreciable increase in oil temperature.

WITHDRAWN: Experimental investigation of hydrodynamic pressure and oil film temperature of surface textured offset halves journal bearing

Abstract The present aim of this paper is to fabricate the surface textured Offset halves journal bearing to study the performance characteristic of the journal bearing. Experimental investigations is carried out to measure the hydrodynamic offset-halve journal bearing performance parameters like oil film pressure and temperature distribution at different loads and constant speed with hydrogl 68 as the lubricating oil. Results reported that the oil film pressure and effective temperature distribution of the lubricating oil are influenced significantly on the radial load and rotational speed. With an increase in the radial load and rotational speed oil film pressure and temperature also increased along the mid-plane of the lobe. The experimental evidence shows that the bearing performance has been improved with surface texture on hydrodynamic journal bearing.

Performance analysis of thrust pad bearing using micro-rectangular pocket and bionic texture

This paper presents the performance behaviors of a hydrodynamic thrust bearing incorporating new pad surface designs involving microrectangular pocket and Labeo rohita fish scale texture. The bearing performance parameters have been numerically explored and analyzed using three different pad surface designs. The effects of texture parameters such as pocket/texture depth, extend of pocket, and fish texture spread in the circumferential and radial directions, the number of scale texture waves in circumferential and radial directions, have been investigated for improving the performance of the bearing. It has been found that the pad surface having microrectangular pocket and fish scale texture together yields substantial increase in minimum film thickness and reduction in friction coefficient as compared to the other pad designs.

Rolling bearing performance rating parameters: Review and engineering assessment

The choice of a rolling bearing for a particular application relies on performance rating parameters as the static, the dynamic, and the fatigue limit load of bearings. The values of these parameters define the calculated performance of the bearing. Endurance testing of high-quality rolling bearings has been used for the development of rolling bearing performance standards like the ISO 281 and ISO 76 that are commonly used throughout the industry. However, standard test methods for the measurement and validation of load ratings of rolling bearings are not available in the standards. This leads to the undifferentiated use of the “status of the art” standardized performance to the very large variety of rolling bearing types and qualities that are produced today. The current paper revisits the origin, definition, and development of rolling bearing performance parameters. A numerical study for the determination process of bearing load ratings is carried out. The results are compared with standardized values and values quoted by bearing manufacturers. This provides an overview of the load rating practices that are in use. The limitations and possible improvements of the present methodology are discussed.

Fluid-structure interaction on the dynamic characteristics of the hydrostatic spindle in micro-scale

PurposeThe purpose of this paper is to investigate the effect of fluid–structure interaction in micro-scale on the performance of the hydrostatic spindle and improve the analysis precision of the dynamic performance of hydrostatic spindle.Design/methodology/approachDynamic analysis of hydrostatic spindle before and after fluid–structure interaction is carried out according to stiffness and damping performance of the bearing, which demonstrates that the natural frequency and peak response of the spindle are increased in the micro-scale.FindingsIt is concluded from the simulation and experimental results that there is micro-scale effect in the actual operation of the spindle system and slippage exists in the oil film flow. The error between the modal detection result and the theoretical value is within 10 per cent, which also verifies the correctness of the above conclusions.Originality/valueThis paper analyzes the changes of the bearing performance parameters at macro- and micro-scale, which present the influence of the static and dynamic performance of the spindle in the micro-scale.

Effect of couple stress parameter on steady-state and dynamic characteristics of three-lobe journal bearing operating on TiO2 nanolubricant

Steady-state and dynamic performance parameters of three-lobe fluid film bearing, operating on TiO2 nanolubricant have been obtained. The effective viscosity for a given volume fraction of TiO2 nanoparticle in base fluid is obtained by using Krieger–Dougherty viscosity model. Various bearing performance parameters are obtained by solving remodeled Reynolds equation, which includes couple stress parameter. The stiffness and damping coefficients are also obtained for different values of the couple stress parameter. Results show a significant rise in the nondimensional load-carrying capacity and flow coefficient while there is a decrease in friction variable. It also reveals a significant improvement in the dynamic coefficient of bearing.

Effect of wear on the performance of hole entry hybrid conical journal bearing employing constant flow valve compensation

Hybrid bearings gets worn gradually during the start and stop operation. This wearing leads to change in the geometry of bearing and affects the radical clearance as well as fluid film thickness. Therefore, these discontinuities in the radial clearance can influence the performance characteristics. With the purpose of preventing irreparable failure state of bearing assembly, it is essential to concentrate on the actual changes in the performance parameters of hole entry hybrid conical journal bearing due to wear. In this context, the main aim of this analysis is to predict the performance of hole entry hybrid conical journal bearing employing constant flow valve compensation. Modified Reynolds equation in spherical coordinate form is used to govern the flow of lubricant in the narrow region between journal and conical bearing. The solution to this Reynolds equation is obtained by finite element analysis with appropriate boundary conditions. This paper summarizes that for a given bearing with constant flow valve as compensating element, the wear causes variation in lubricant film thickness, which strongly affects load capacity, pressure generated, and dynamic performance parameters.