Closure to “Discussions of ‘The Effects on Bearing Load-Carrying Capacity of Two-Sided Striated Roughness’” (1974, ASME J. Lubr. Technol., 96, pp. 558–560)

1974 ◽  
Vol 96 (4) ◽  
pp. 560-560
Author(s):  
S. K. Rhow ◽  
H. G. Elrod
Keyword(s):  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Bearing Load

Geometry Optimization of Textured Three-Dimensional Micro- Thrust Bearings

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
C. I. Papadopoulos ◽  
E. E. Efstathiou ◽  
P. G. Nikolakopoulos ◽  
L. Kaiktsis
Keyword(s):  
Carrying Capacity ◽  
Stokes Equations ◽  
Load Capacity ◽  
Three Dimensional ◽  
Load Carrying Capacity ◽  
Thrust Bearings ◽  
Micro Channels ◽  
Wide Range ◽  
Load Carrying ◽  
Bearing Load

This paper presents an optimization study of the geometry of three-dimensional micro-thrust bearings in a wide range of convergence ratios. The optimization goal is the maximization of the bearing load carrying capacity. The bearings are modeled as micro-channels, consisting of a smooth moving wall (rotor), and a stationary wall (stator) with partial periodic rectangular texturing. The flow field is calculated from the numerical solution of the Navier-Stokes equations for incompressible isothermal flow; processing of the results yields the bearing load capacity and friction coefficient. The geometry of the textured channel is defined parametrically for several width-to-length ratios. Optimal texturing geometries are obtained by utilizing an optimization tool based on genetic algorithms, which is coupled to the CFD code. Here, the design variables define the bearing geometry and convergence ratio. To minimize the computational cost, a multi-objective approach is proposed, consisting in the simultaneous maximization of the load carrying capacity and minimization of the bearing convergence ratio. The optimal solutions, identified based on the concept of Pareto dominance, are equivalent to those of single-objective optimization problems for different convergence ratio values. The present results demonstrate that the characteristics of the optimal texturing patterns depend strongly on both the convergence ratio and the width-to-length ratio. Further, the optimal load carrying capacity increases at increasing convergence ratio, up to an optimal value, identified by the optimization procedure. Finally, proper surface texturing provides substantial load carrying capacity even for parallel or slightly diverging bearings. Based on the present results, we propose simple formulas for the design of textured micro-thrust bearings.

Theoretical and experimental investigation of the effect of oil aeration on the load-carrying capacity of a hydrodynamic journal bearing

2007 ◽  
Vol 221 (7) ◽  
pp. 779-786 ◽  
Author(s):  
M. J. Goodwin ◽  
D Dong ◽  
H Yu ◽  
J. L. Nikolajsen
Keyword(s):  
Carrying Capacity ◽  
Lubricating Oil ◽  
Hydrodynamic Effect ◽  
Air Bubbles ◽  
Load Carrying Capacity ◽  
Hydrodynamic Bearing ◽  
Low Viscosity ◽  
Discernible Effect ◽  
Load Carrying ◽  
Bearing Load

It is widely assumed that the presence of air bubbles in the lubricating oil of a hydrodynamic bearing gives rise to a reduced load-carrying capacity, because of the high compressibility and low viscosity of the air and its tendency, therefore, to upset the hydrodynamic effect. The aim of the work described in the current paper was to investigate the accuracy of this assumption by theoretical and experimental means, and also to provide quantitative data relating to the concentration of air bubbles and their size that are required for any discernible effect. The paper has the following three main contributions: (a) a theoretical model based on Reynolds equation, but modified to allow for the effect of aeration on lubricant viscosity and density, is proposed; (b) a novel method of injecting air bubbles into lubricating oil and for measuring their size and concentration was developed; and (c) an experimental hydrodynamic bearing test rig was implemented and run with both aerated and non-aerated lubricating oil, and in each case measurements of the load-carrying capacity for various operating speeds were made. The results from both theoretical and experiment work show that the presence of air bubbles in the lubricating oil leads to a slight decrease in bearing load-carrying capacity at high operating speeds. For normal operating speeds, however, (i.e. those resulting in eccentricity ratios greater than 0.6) results show that the presence of air bubbles has little effect on bearing load-carrying capacity.

On the Combined Effects of Lubricant Inertia and Viscous Dissipation in Long Bearings

1997 ◽  
Vol 119 (1) ◽  
pp. 76-84 ◽  
Author(s):  
E. Kim ◽  
A. Z. Szeri
Keyword(s):  
Carrying Capacity ◽  
Journal Bearings ◽  
Isothermal Flow ◽  
Nonisothermal Flow ◽  
Combined Effects ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Bearing Load ◽  
The Stability ◽  
Rate Of Dissipation

We have demonstrated earlier that for laminar, isothermal flow of the lubricant in the non-cavitating film of long journal bearings, inertia has negligible effect on the load-carrying capacity and influences only the stability characteristics of the bearing. The question we pose in the present paper is: “will these conclusions remain valid for nonisothermal flow, or will lubricant inertia and dissipation interact and result in significant changes in bearing performance?” The results obtained here assert that the effect of lubricant inertia on load-carrying capacity remains negligible, irrespective of the rate of dissipation. The stability of the bearing is, however, affected by lubricant inertia. These results, although obtained here for long bearings and noncavitating films, are believed to be applicable to some practical bearing operations and suggest that for these, bearing load may be calculated from classical, i.e., noninertial theory.

The Effects on Bearing Load-Carrying Capacity of Two-Sided Striated Roughness

1974 ◽  
Vol 96 (4) ◽  
pp. 554-558 ◽  
Author(s):  
S. K. Rhow ◽  
H. G. Elrod
Keyword(s):  
Carrying Capacity ◽  
Multiple Scale ◽  
Load Carrying Capacity ◽  
Transient Effects ◽  
Slider Bearing ◽  
Scale Method ◽  
Load Carrying ◽  
Bearing Load ◽  
Order Of Magnitude ◽  
Final Equation

The multiple-scale method which was earlier employed for lubricating films with striated roughness on one of two opposing surfaces is here extended to include striated roughness on both surfaces. In some papers, the transient effects due to the roughness have been neglected. However, the present analysis shows that the term representing these effects is of the same order of magnitude as others retained in the final equation governing the average pressure. As an example, it is shown that with the same overall roughness characteristics, the load-carrying capacity of an infinitely wide slider bearing varies according to how the same roughness is distributed on opposing surfaces.

Study on Lubrication Simulation and Capability of Three-Lobe Journal Bearing

2014 ◽  
Vol 709 ◽  
pp. 210-214
Author(s):  
Kun Qian ◽  
Wei Gang Guo
Keyword(s):  
Carrying Capacity ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Rotation Speed ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Bearing Load ◽  
The Stability ◽  
Eccentric Distance

The lubrication state of three-lobe bearing is simulated by using Reynolds equation. It concluded that the load-carrying capability of three-lobe bearing increases with the eccentric distance between the centers of axis and bearing with a nonlinear way. The largest bearing load-carrying capacity occurs in the eccentric direction of 30 °and making sure the eccentric direction can improve the stability of the system. To improve the rotation speed of the axis is beneficial to promote the load-carrying capacity.

scholarly journals Assessing the Potential Replacement of Mineral Oil with Environmentally Acceptable Lubricants in a Stern Tube Bearing: An Experimental Analysis of Bearing Performance

2021 ◽  
Vol 28 (4) ◽  
pp. 160-166
Author(s):  
Jerzy Kowalski ◽  
Wojciech Leśniewski ◽  
Daniel Piątek ◽  
Dominika Cuper Przybylska
Keyword(s):  
Carrying Capacity ◽  
Measurement Errors ◽  
Mineral Oil ◽  
Diameter Ratio ◽  
Load Carrying Capacity ◽  
Plain Bearing ◽  
Iso Standard ◽  
Load Carrying ◽  
Bearing Load ◽  
Viscosity Grade

Abstract This study compares the performance of a plain bearing, with a similar structure to a tail shaft stern bearing, lubricated with either mineral oil or an environmentally acceptable lubricant (EAL). The main characteristic of the bearing is its length/diameter ratio of <1. Measurements are carried out with the bearing operating under loads from 0.5 to 1 MPa and seven speeds ranging from 1 to 11 rev/s. The bearing lubricated with either mineral oil with a viscosity grade of 100 or an environmentally acceptable lubricant (EAL) with a viscosity grade of 100 or 150 is investigated according to the ISO standard. Bearing wear is simulated by increasing the clearance circle by 0.1 mm. According to the results obtained, the use of an EAL in place of mineral oil does not cause significant changes in the bearing performance, regardless of the value of the clearance radius. The pressure distribution in the oil film, bearing load carrying capacity, eccentricity and friction coefficient have similar values for the entire load and speed ranges considered, and the discrepancies in the results are within the range of the measurement errors. Only an increase in EAL viscosity causes significant changes in bearing performance and these changes comply with the general theory of lubrication.

Geometry Optimization of Textured 3-D Micro-Thrust Bearings

2011 ◽  
Author(s):  
C. I. Papadopoulos ◽  
E. E. Efstathiou ◽  
P. G. Nikolakopoulos ◽  
L. Kaiktsis
Keyword(s):  
Carrying Capacity ◽  
Stokes Equations ◽  
Optimization Problems ◽  
Load Capacity ◽  
Computational Cost ◽  
Load Carrying Capacity ◽  
Thrust Bearings ◽  
Wide Range ◽  
Load Carrying ◽  
Bearing Load

The paper presents an optimization study of the geometry of three-dimensional micro-thrust bearings, in a wide range of convergence ratios. The optimization goal is the maximization of the bearing load carrying capacity. The bearings are modeled as microchannels, consisting of a smooth moving wall (rotor), and a stationary wall (stator) with partial periodic rectangular texturing. The flow field is calculated from the numerical solution of the Navier-Stokes equations for incompressible isothermal flow; processing of the results yields the bearing load capacity and friction coefficient. The geometry of the textured channel is defined parametrically for several width-to-length ratios. Optimal texturing geometries are obtained by utilizing an optimization tool based on genetic algorithms, which is coupled to the CFD code. Here, the design variables define the bearing geometry and convergence ratio. To minimize the computational cost, a multi-objective approach is proposed, consisting in the simultaneous maximization of the load carrying capacity and minimization of the bearing convergence ratio. The optimal solutions, identified based on the concept of Pareto dominance, are equivalent to those of single-objective optimization problems at different convergence ratio values. The present results demonstrate that the characteristics of the optimal texturing patterns depend strongly on both the convergence ratio and the width-to-length ratio. Further, the optimal load carrying capacity increases at increasing convergence ratio, up to an optimal value, identified by the optimization procedure. Finally, proper surface texturing provides substantial load carrying capacity even for parallel or slightly diverging bearings. Based on the present results, we propose simple formulas for the design of textured micro-thrust bearings.

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