Performance of Balancing Wedge Action in Textured Hydrodynamic Pad Bearings

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Kazuyuki Yagi ◽  
Joichi Sugimura
Keyword(s):  
Carrying Capacity ◽  
Reynolds Equation ◽  
Central Area ◽  
Numerical Results ◽  
Load Carrying Capacity ◽  
One Dimensional ◽  
Stationary Surface ◽  
Load Carrying ◽  
Balance Solution

This study investigates a mechanism of textured features taking into account the balance of moment termed “balancing wedge action.” The principle of the suggested mechanism is that a change in moment applied to the lubricated area by incorporating textured features promotes the entire wedge action over the lubricated area. In the current study, multiple dimples are created on the stationary surface of an infinite pad bearing. A one-dimensional incompressible Reynolds equation is solved numerically to determine the load-carrying capacity of infinite pad bearings with a centrally located pivot. Numerical results show the importance of the balancing wedge action. When multiple dimples are created at the inlet side or outlet side of the lubricated area, positive load-carrying capacity is realized. When multiple dimples are located around the central area, no balance solution is obtained for the pad. The dimple depth, width, and distribution are varied to investigate the behavior of the load-carrying capacity realized by the action of the balancing wedge.

The Validity of the Reynolds Equation in Modeling Hydrostatic Effects in Gas Lubricated Textured Parallel Surfaces

2005 ◽  
Vol 128 (2) ◽  
pp. 345-350 ◽  
Author(s):  
Y. Feldman ◽  
Y. Kligerman ◽  
I. Etsion ◽  
S. Haber
Keyword(s):  
Carrying Capacity ◽  
Reynolds Equation ◽  
Stokes Equations ◽  
Surface Texturing ◽  
Laser Surface Texturing ◽  
Physical Parameters ◽  
Load Carrying Capacity ◽  
Wide Range ◽  
Load Carrying ◽  
Parallel Surfaces

Microdimples generated by laser surface texturing (LST) can be used to enhance performance in hydrostatic gas-lubricated tribological components with parallel surfaces. The pressure distribution and load carrying capacity for a single three-dimensional dimple, representing the LST, were obtained via two different methods of analysis: a numerical solution of the exact full Navier-Stokes equations, and an approximate solution of the much simpler Reynolds equation. Comparison between the two solution methods illustrates that, despite potential large differences in local pressures, the differences in load carrying capacity, for realistic geometrical and physical parameters, are small. Even at large clearances of 5% of the dimple diameter and pressure ratios of 2.5 the error in the load carrying capacity is only about 15%. Thus, for a wide range of practical clearances and pressures, the simpler, approximate Reynolds equation can safely be applied to yield reasonable predictions for the load carrying capacity of dimpled surfaces.

Hydrodynamic Lubrication of Finite Slider Bearings: Effect of One Dimensional Film Shape, and Their Computer Aided Optimum Designs

1983 ◽  
Vol 105 (1) ◽  
pp. 48-63 ◽  
Author(s):  
C. Bagci ◽  
A. P. Singh
Keyword(s):  
Numerical Solution ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
Load Carrying Capacity ◽  
Slider Bearing ◽  
Design Data ◽  
Slider Bearings ◽  
Load Carrying ◽  
Computer Aided

The effect of the film shape on the load carrying capacity of a hydrodynamically lubricated bearing has not been considered an important factor in the past. Flat-faced tapered bearing and the Raileigh’s step bearing of constant film thickness have been the primary forms of film shapes for slider bearing studies and design data developments. This article, by the computer aided numerical solution of the Reynolds equation for two dimensional incompressible lubricant flow, investigates hydrodynamically lubricated slider bearings having different film shapes and studies the effect of the film shape on the performance characteristics of finite bearings; and it shows that optimized bearing with film shapes having descending slope toward the trailing edge of the bearing has considerably higher load carrying capacity than the optimized flat-faced tapered bearing of the same properties. For example the truncated cycloidal film shape yields 26.3 percent higher load carrying capacity for Lz/Lx = 1 size ratio, and 44 percent higher for Lz/Lx = 1/2. The article then presents charts for the optimum designs of finite slider bearings having tapered, exponential, catenoidal, polynomial, and truncated-cycloidal film shapes, and illustrates their use in numerical bearing design examples. These charts also furnish information on flow rate, side leakage, temperature rise, coefficient of friction, and friction power loss in optimum bearings. Appended to the article are analytical solutions for infinitely wide bearings with optimum bearing characteristics. The computer aided numerical solution of the Reynolds equation in most general form is presented by which finite or infinitely wide hydrodynamically or hydrostatically lubricated bearings, externally pressurized or not, can be studied. A digital computer program is made available.

The Performance of Hydrodynamic Lubricating Films With Viscosity Variations Perpendicular to the Direction of Motion

1972 ◽  
Vol 94 (1) ◽  
pp. 44-48 ◽  
Author(s):  
E. B. Qvale ◽  
F. R. Wiltshire
Keyword(s):  
Film Thickness ◽  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
End Effects ◽  
Parametric Curves ◽  
One Dimensional ◽  
Lubricating Film ◽  
Families Of Curves ◽  
Load Carrying ◽  
The Coefficient Of Friction

The effects of prescribed viscosity variations across a hydrodynamic lubricating film are studied. The film is strictly one dimensional and end effects are neglected. The viscosity variations are given by three families of curves. The considerable decreases (in the limit 100 percent) and occasional increases in the coefficient of friction that can occur for constant film thickness and load-carrying capacity are evaluated and the results are presented in terms of parametric curves. Important physical situations where these viscosity variations may be observed or produced are described.

Evaluation of Dynamic Load-Carrying Capacity for Free-Floating Space Manipulators

2015 ◽  
Vol 713-715 ◽  
pp. 795-799 ◽  
Author(s):  
Yong Liu ◽  
Qing Xuan Jia ◽  
Gang Chen ◽  
Han Xu Sun ◽  
Jun Jie Peng
Keyword(s):  
Dynamic Load ◽  
Carrying Capacity ◽  
Function Method ◽  
Feasible Region ◽  
Penalty Function Method ◽  
Load Carrying Capacity ◽  
One Dimensional ◽  
Space Manipulators ◽  
Load Carrying ◽  
Point To Point

Two kinds of dynamic load-carrying capacity (DLCC) evaluation methods for free-floating space manipulators (FFSM) in two typical on-orbit operating missions are proposed in this paper. DLCC evaluation is transformed into nonlinear programming problem (NPP) by introducing load-carrying coefficient to measure DLCC: in point-to-point task, penalty function method is adopted to approach the boundary of feasible region rapidly, then DLCC can be obtained through following iterations; in trajectory tracking task, NPP is solved by using multiple one-dimensional search, the dynamic load-carrying coefficient in discontinuous feasible region can be quickly solved through adjusting the searching boundary constantly. The effectiveness of the mentioned methods is verified by simulations.

Theoretical Analysis of Externally Pressurized Air Journal Bearing

1970 ◽  
Vol 12 (2) ◽  
pp. 123-129 ◽  
Author(s):  
B. C. Majumdar
Keyword(s):  
Experimental Data ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Design Parameters ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Dimensional Parameters ◽  
Bearing Design

A theoretical investigation is made to predict the performance of an externally pressurized air journal bearing having several pressure sources. The pressure distribution, which leads to the determination of load-carrying capacity and flow requirement, is obtained by solving Reynolds equation numerically. The load and flow, expressed in non-dimensional parameters, are presented for different bearing design parameters (dimensionless). The results predicted by this method are compared with others' experimental data.

scholarly journals Stability and Load-Carrying Capacity of Thin-Walled FRP Composite Z-Profiles under Eccentric Compression

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2956
Author(s):  
Hubert Debski ◽  
Sylwester Samborski ◽  
Patryk Rozylo ◽  
Pawel Wysmulski
Keyword(s):  
Composite Material ◽  
Carrying Capacity ◽  
Progressive Failure ◽  
Compressive Load ◽  
Experimental Tests ◽  
Numerical Results ◽  
Load Carrying Capacity ◽  
Plastic Composite ◽  
Load Carrying ◽  
Thin Walled

This study investigates the effect of eccentric compressive load on the stability, critical states and load-carrying capacity of thin-walled composite Z-profiles. Short thin-walled columns made of carbon fiber-reinforced plastic composite material fabricated by the autoclave technique are examined. In experimental tests, the thin-walled structures were compressed until a loss of their load-carrying capacity was obtained. The test parameters were measured to describe the structure’s behavior, including the phenomenon of composite material failure. The post-critical load-displacement equilibrium paths and the acoustic emission signal enabling analysis of the composite material condition during the loading process were measured. The scope of the study also included performing numerical simulations by finite element method to solve the problem of non-linear stability and to describe the phenomenon of composite material damage based on the progressive failure model. The obtained numerical results showed a good agreement with the experimental characteristics of real structures. The numerical results are compared with the experimental findings to validate the developed numerical model.

On the study of Rayleigh step slider bearings lubricated with non-Newtonian Rabinowitsch fluid

2017 ◽  
Vol 69 (5) ◽  
pp. 666-672
Author(s):  
N.B. Naduvinamani ◽  
Siddharam Patil ◽  
S.S. Siddapur
Keyword(s):  
Carrying Capacity ◽  
Reynolds Equation ◽  
Maximum Load ◽  
Load Carrying Capacity ◽  
Slider Bearing ◽  
Content Type ◽  
Slider Bearings ◽  
Load Carrying ◽  
Modified Reynolds Equation ◽  
Frictional Coefficients

Purpose Nowadays, the use of Newtonian fluid as a lubricant is diminishing day by day, and the use of non-Newtonian fluids has gained importance. This paper presents an analysis of the static characteristics of Rayleigh step slider bearing lubricated with non-Newtonian Rabinowitsch fluid, which has not been studied so far. The purpose of this paper is to derive the modified Reynolds equation for Rabinowitsch fluids for two regions and to obtain the optimum bearing parameters for the Rayleigh step slider bearings. Design/methodology/approach The governing equations relevant to the problem under consideration are derived. The modified Reynolds equation is derived, and it is found to be highly non-linear and hence small perturbation method is adopted to find solution. Findings From this study it is found that there is an increase in the load-carrying capacity, pressure and frictional coefficients for dilatant fluids as compared to the corresponding Newtonian case. Further, for dilatant lubricants the maximum load-carrying capacity is attained for the slightly larger values of entry region length of Rayleigh step bearing as compared to Newtonian and pseudoplastic lubricants. Originality/value Rabinowitsch fluid is used for the study of lubrication characteristics of Rayleigh step bearings. The author believes that the paper presents these results for the first time.

Effect of viscosity variation on non-Newtonian lubrication of squeeze film conical bearing having porous wall operating with Rabinowitsch fluid model

2018 ◽  
Vol 233 (7) ◽  
pp. 2538-2551 ◽  
Author(s):  
Pentyala Srinivasa Rao ◽  
Amit Kumar Rahul
Keyword(s):  
Carrying Capacity ◽  
Reynolds Equation ◽  
Porous Wall ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Film Pressure ◽  
Pressure Load ◽  
Load Carrying ◽  
Newtonian Case ◽  
Viscosity Variation

In this study, the effect of viscosity variation of non-Newtonian lubrication on squeeze film characteristics with porous and Rabinowitsch fluid for conical bearings is analyzed. The modified Reynolds equation representing the characteristics of non-Newtonian fluid with viscosity variation on the porous wall followed by the cubic stress law condition is invoked. For lubricant flow in a bearing clearance and in a porous layer Morgan–Cameron approximation is considered. A small perturbation technique is used to compute the pressure generation using modified Reynolds equation of lubrication. Approximate analytical solutions have been obtained for the squeeze film pressure, load-carrying capacity, squeeze film time, and center of pressure. The outcomes are displayed in diagrams and tables, which show that the effect of viscosity variation and porous wall on the squeeze film lubrication of conical bearings decreases film pressure, load-carrying capacity, and response time for the Newtonian case in comparison to the non-Newtonian case.

scholarly journals Non-Newtonian Effects on the Squeeze Film Characteristics between a Sphere and a Flat Plate: Rabinowitsch Model

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Udaya P. Singh ◽  
Ram S. Gupta
Keyword(s):  
Flat Plate ◽  
Carrying Capacity ◽  
Significant Variation ◽  
Reynolds Equation ◽  
Fluid Model ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Film Pressure ◽  
Load Carrying ◽  
Film Characteristics

The use of additives (polyisobutylene, ethylene-propylene, lithium hydroxy stearate, hydrophobic silica, etc.) changes lubricants’ rheology due to which they show pseudoplastic and dilatant nature, which can be modelled as cubic stress fluid model (Rabinowitsch fluid model). The present theoretical analysis investigates the effects of non-Newtonian pseudoplastic and dilatant lubricants on the squeezing characteristics of a sphere and a flat plate. The modified Reynolds equation has been derived and an asymptotic solution for film pressure is obtained. The results for the film pressure distribution, load carrying capacity, and squeezing time characteristics have been calculated for various values of pseudoplastic parameter and compared with the Newtonian results. These characteristics show a significant variation with the non-Newtonian pseudoplastic and dilatant behavior of the fluids.

Elastic Deformation Effects on the Thermo-Hydrodynamic Aspect of Porous Journal Bearings

2014 ◽  
Vol 353 ◽  
pp. 275-279
Author(s):  
S. Boubendir ◽  
Salah Larbi ◽  
R. Bennacer
Keyword(s):  
Elastic Deformation ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Maximum Pressure ◽  
Load Carrying Capacity ◽  
Static Characteristics ◽  
Governing Equations ◽  
Load Carrying ◽  
Variation Parameter ◽  
Viscosity Variation

In this paper, the effects of porous bush elastic deformation on the static characteristics of finite porous journal bearing are investigated using Darcy’s law. The modified Reynolds equation applied to thermo-hydrodynamic problems is modified by considering the viscosity variation along the film thickness. The film pressure distribution and other characteristics such as the load carrying capacity and attitude angle are obtained by solving the governing equations numerically. Obtained results showed that deformation is considerable in the maximum pressure zone, and the elastic deformation will decrease the load carrying capacity. The viscosity variation parameter tends also to decrease the load carrying capacity.

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