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.

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.

Analysis of a circular journal bearing lubricated with micropolar fluids including EHD effects

2014 ◽  
Vol 66 (2) ◽  
pp. 168-173 ◽  
Author(s):  
Boualem Chetti
Keyword(s):  
Elastic Deformation ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Newtonian Fluids ◽  
Load Carrying Capacity ◽  
Micropolar Fluids ◽  
Content Type ◽  
Load Carrying ◽  
Modified Reynolds Equation

Purpose – The performance of finite circular journal bearing lubricated with micropolar fluids taking into account the elastic deformation of the bearing liner is presented. The paper aims to discuss these issues. Design/methodology/approach – The modified Reynolds equation is obtained using the micropolar lubrication theory. The solution of the modified Reynolds equation is determined using finite difference technique. The static characteristics in terms of load-carrying capacity, attitude angle, side leakage and friction coefficient for micropolar and Newtonian fluids are determined for various values of eccentricity ratio and different values of elastic coefficient. Findings – Compared with Newtonian fluids, the micropolar fluids produce an increase in the load-carrying capacity and a reduction in the attitude angle, the friction factor and side leakage for both the rigid and deformable bearings. Originality/value – It is concluded that the influence of elastic deformation on the bearing characteristics lubricated with micropolar fluids is significantly apparent compared with bearing lubricated with Newtonian fluids.

The Pivoted, Spherical Cap Slider Bearing

1982 ◽  
Vol 104 (2) ◽  
pp. 216-219
Author(s):  
J. W. Lund
Keyword(s):  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Slider Bearing ◽  
Piston Motion ◽  
Spherical Cap ◽  
Slider Bearings ◽  
Positive Displacement ◽  
Load Carrying

In hydraulic pumps of the positive displacement type, the shoes which guide the piston motion may be designed as pivoted slider bearings. One such design, where the bearing geometry is that of a spherical cap, is analyzed and results are presented for the load carrying capacity and the friction.

An Analysis of Powder Lubricated Slider Bearings

1996 ◽  
Vol 118 (1) ◽  
pp. 206-214 ◽  
Author(s):  
K. T. McKeague ◽  
M. M. Khonsari
Keyword(s):  
Boundary Conditions ◽  
Carrying Capacity ◽  
Parametric Study ◽  
Experimental Measurements ◽  
Load Carrying Capacity ◽  
General Boundary Conditions ◽  
Slider Bearing ◽  
Slider Bearings ◽  
Load Carrying ◽  
Theoretical Predictions

A theory for predicting the behavior of powder lubricated slider bearings based on the collisional characteristics of the grain particles and their interactions at the boundaries is presented. General boundary conditions that account for the effects of powder slippage are applied to the slider bearing configuration. Theoretical predictions are presented with comparison to published experimental measurements. An extensive parametric study is also conducted to illustrate the behavior of the flow and the response of the bearing’s load-carrying capacity and friction factor to changes in various powder material and boundary parameters.

scholarly journals Effect of Viscosity Variation on the Micropolar Fluid Squeeze Film Lubrication of a Short Journal Bearing

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
N. B. Naduvinamani ◽  
Archana K. Kadadi
Keyword(s):  
Carrying Capacity ◽  
Micropolar Fluid ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Closed Form Solution ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Viscosity Variation ◽  
Modified Reynolds Equation

A theoretical study of the effect of the viscosity variation on the squeeze film performance of a short journal bearing operating with micropolar fluid is presented. The modified Reynolds equation accounting for the viscosity variation in micropolar fluid is mathematically derived. To obtain a closed form solution, the short bearing approximation under constant load is considered. The modified Reynolds equation is solved for the fluid film pressure and then the bearing characteristics, such as obtaining the load carrying capacity and the squeeze film time. According to the results evaluated, the micropolar fluid as a lubricant improves the squeeze film characteristics and results in a longer bearing life, whereas the viscosity variation factor decreases the load carrying capacity and squeezes film time. The result is compared with the corresponding Newtonian case.

Optimization of texture geometry for a rotating ring to maximum load-carrying capacity

2019 ◽  
Vol 71 (5) ◽  
pp. 657-663
Author(s):  
Zaihao Tian ◽  
Jin-Kui Ma ◽  
Lu Changhou ◽  
Shu-Jiang Chen
Keyword(s):  
Carrying Capacity ◽  
Maximum Load ◽  
Computational Domain ◽  
Load Carrying Capacity ◽  
Flat Bottom ◽  
Film Pressure ◽  
Content Type ◽  
Surface Textures ◽  
Surface Contour ◽  
Load Carrying

Purpose The purpose of this paper is to maximize the load-carrying capacity (LCC) of a rotating ring, a numerical model optimizing both the surface and bottom shape of its surface textures is proposed. Design/methodology/approach The Reynolds equation is used to evaluate the film pressure and LCC obtained by integrating the film pressure is set as the objective function. Around the center of the computational domain, radial lines with an equal angle between adjacent ones are produced and the surface contour of textures is obtained by connecting the endpoints using a spline curve. The bottom profile is then obtained by connecting the endpoints of two vertical lines at the circumferential ends of textures. Lengths of these lines are set as design variables and genetic algorithm is used to solve optimization models. Findings Results show that optimum textures have an “apple-like” surface contour and a “wedge-like” bottom profile, which are both expressed by smooth spline curves. Optimum wedge-bottom textures generate higher LCC than optimum flat-bottom textures. Moreover, the optimum textures have the highest LCC compared with optimum grooves proposed previously, which validates the practical value of the current optimization model. Originality/value This work presents a comprehensive optimization method of texture geometry, which provides a new idea of the design of surface textures.

Higher Order Approximations in the Asymptotic Solution of the Reynolds Equation for Slider Bearings at High Bearing Numbers

1969 ◽  
Vol 91 (1) ◽  
pp. 45-51 ◽  
Author(s):  
R. C. DiPrima
Keyword(s):  
Carrying Capacity ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Higher Order ◽  
Load Carrying Capacity ◽  
Slider Bearing ◽  
Load Carrying ◽  
Higher Order Terms ◽  
Parabolic Shape ◽  
Bearing Number

The methods of matched asymptotic expansions are used in a systematic manner to obtain the load-carrying capacity of an infinitely long slider bearing correct through terms 0 (1/Λ) where Λ is the bearing number. The expression for the load is extremely simple. It is shown that the error is 0 (1/Λ2), and the procedure for obtaining higher order terms is discussed. Results are given for the case of a converging film thickness with a parabolic shape and for a partial arc journal bearing.

Perturbation Solution of the 1-D Reynolds Equation With Slip Boundary Conditions

1978 ◽  
Vol 100 (1) ◽  
pp. 70-73 ◽  
Author(s):  
Aron Sereny ◽  
Vittorio Castelli
Keyword(s):  
Boundary Conditions ◽  
Numerical Solution ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Load Carrying Capacity ◽  
Slip Boundary Conditions ◽  
Slider Bearing ◽  
Slip Boundary ◽  
Load Carrying ◽  
Bearing Number

The method of matched asymptotic expansion is applied to obtain the pressure distribution and the load carrying capacity for an infinitely long slider bearing, operating under high-speed, low-height, with slip boundary conditions. The pressure distribution is easily applicable as the starting solution for the iterative numerical solution of Reynolds equation. Two examples given show extremely good correlation between this expansion and the numerical solution. It is shown that, for a tapered slider bearing with a bearing number above 100, the reduction in load because of slip is minimal and that, for a parabolic slider, there exists a certain unique bearing number for which the load carrying capacity is independent of the parabolic crown of the slider. It is shown that for a wide slider bearing with large bearing number, the effect of slip is on the order of 1/A.

Waviness and Roughness in Hydrodynamic Lubrication

1972 ◽  
Vol 186 (1) ◽  
pp. 807-812 ◽  
Author(s):  
K. Tønder ◽  
H. Christensen
Keyword(s):  
Carrying Capacity ◽  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
Load Carrying Capacity ◽  
Slider Bearings ◽  
Load Carrying ◽  
Pressure Ripples

An analysis of the effect of waviness on lubrication is presented. This analysis consists of direct solutions of the Reynolds equation for corrugated slider bearings under various conditions. It is shown how the corrugation wavelength is a major factor, pressure ripples vanishing with increasing corrugation density. It is further shown that at the same time, the load-carrying capacity tends towards that predicted by the authors' statistical roughness theory, the analysis thus constituting a numerical proof of the mathematical soundness of that theory.

Maximum load carrying capacity of mobile manipulators: optimal control approach

Robotica ◽  
2009 ◽  
Vol 27 (1) ◽  
pp. 147-159 ◽  
Author(s):  
M. H. Korayem ◽  
A. Nikoobin ◽  
V. Azimirad
Keyword(s):  
Optimal Control ◽  
Optimal Control Problem ◽  
Control Problem ◽  
Carrying Capacity ◽  
Nonholonomic Constraints ◽  
Maximum Load ◽  
Mobile Manipulators ◽  
Load Carrying Capacity ◽  
Maximum Payload ◽  
Load Carrying

SUMMARYIn this paper, finding the maximum load carrying capacity of mobile manipulators for a given two-end-point task is formulated as an optimal control problem. The solution methods of this problem are broadly classified as indirect and direct. This work is based on the indirect solution which solves the optimization problem explicitly. In fixed-base manipulators, the maximum allowable load is limited mainly by their joint actuator capacity constraints. But when the manipulators are mounted on the mobile bases, the redundancy resolution and nonholonomic constraints are added to the problem. The concept of holonomic and nonholonomic constraints is described, and the extended Jacobian matrix and additional kinematic constraints are used to solve the extra DOFs of the system. Using the Pontryagin's minimum principle, optimality conditions for carrying the maximum payload in point-to-point motion are obtained which leads to the bang-bang control. There are some difficulties in satisfying the obtained optimality conditions, so an approach is presented to improve the formulation which leads to the two-point boundary value problem (TPBVP) solvable with available commands in different softwares. Then, an algorithm is developed to find the maximum payload and corresponding optimal path on the basis of the solution of TPBVP. One advantage of the proposed method is obtaining the maximum payload trajectory for every considered objective function. It means that other objectives can be achieved in addition to maximize the payload. For the sake of comparison with previous results in the literature, simulation tests are performed for a two-link wheeled mobile manipulator. The reasonable agreement is observed between the results, and the superiority of the method is illustrated. Then, simulations are performed for a PUMA arm mounted on a linear tracked base and the results are discussed. Finally, the effect of final time on the maximum payload is investigated, and it is shown that the approach presented is also able to solve the time-optimal control problem successfully.

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