Elastomer Inertia Effects in Compliant Surface Bearings

1973 ◽  
Vol 95 (3) ◽  
pp. 372-380 ◽  
Author(s):  
J. Pirvics ◽  
V. Castelli
Keyword(s):  
Steady State ◽  
Pressure Distribution ◽  
Journal Bearing ◽  
Analytical Techniques ◽  
Operating Conditions ◽  
Infinite Length ◽  
Inertial Effects ◽  
Inertia Effects ◽  
Compliant Surface ◽  
Bearing System

A bearing system using a compliant surface may be so constructed that the lubricant pressure distribution is either stationary or in motion relative to the elastomer. In the latter case the motion of the deformation in the elastomer introduces inertial effects which can be important at high enough bearing velocities. This paper is concerned with the assessment of these effects. Steady state operating conditions are computed and analytical techniques presented for the infinite width slider and infinite length journal bearing.

Elastomer Viscoelasticity Effects in Compliant Surface Bearings

1973 ◽  
Vol 95 (3) ◽  
pp. 363-371 ◽  
Author(s):  
J. Pirvics ◽  
V. Castelli
Keyword(s):  
Steady State ◽  
Pressure Distribution ◽  
Journal Bearing ◽  
Analytical Techniques ◽  
Operating Conditions ◽  
Infinite Length ◽  
Compliant Surface ◽  
Viscoelastic Effects ◽  
Bearing System

A bearing system using a compliant surface may be so constructed that the lubricant pressure distribution is either stationary or in motion relative to the elastomer. In the latter case the motion of the deformation in the elastomer introduces viscoelastic effects which can be important at conventional bearing velocities. This paper is concerned with the assessment of these effects. Steady state operating conditions are computed and analytical techniques presented for the infinite width slider and infinite length journal bearing.

A Multiscale Method Modeling Surface Texture Effects

2006 ◽  
Vol 129 (2) ◽  
pp. 221-230 ◽  
Author(s):  
Alex de Kraker ◽  
Ron A. J. van Ostayen ◽  
A. van Beek ◽  
Daniel J. Rixen
Keyword(s):  
Surface Texture ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Stokes Equations ◽  
Multiscale Method ◽  
Operating Conditions ◽  
Contact Load ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Inertia Effects

In this paper a multiscale method is presented that includes surface texture in a mixed lubrication journal bearing model. Recent publications have shown that the pressure generating effect of surface texture in bearings that operate in full film conditions may be the result of micro-cavitation and/or convective inertia. To include inertia effects, the Navier–Stokes equations have to be used instead of the Reynolds equation. It has been shown in earlier work (de Kraker et al., 2006, Tribol. Trans., in press) that the coupled two-dimensional (2D) Reynolds and 3D structure deformation problem with partial contact resulting from the soft EHL journal bearing model is not easy to solve due to the strong nonlinear coupling, especially for soft surfaces. Therefore, replacing the 2D Reynolds equation by the 3D Navier–Stokes equations in this coupled problem will need an enormous amount of computing power that is not readily available nowadays. In this paper, the development of a micro–macro multiscale method is described. The local (micro) flow effects for a single surface pocket are analyzed using the Navier–Stokes equations and compared to the Reynolds solution for a similar smooth piece of surface. It is shown how flow factors can be derived and added to the macroscopic smooth flow problem, that is modeled by the 2D Reynolds equation. The flow factors are a function of the operating conditions such as the ratio between the film height and the pocket dimensions, the surface velocity, and the pressure gradient over a surface texture unit cell. To account for an additional pressure buildup in the texture cell due to inertia effects, a pressure gain is introduced at macroscopic level. The method also allows for microcavitation. Microcavitation occurs when the pressure variation due to surface texture is larger than the average pressure level at that particular bearing location. In contrast with the work of Patir and Cheng (1978, J. Lubrication Technol., 78, pp. 1–10), where the microlevel is solved by the Reynolds equation, and the Navier–Stokes equations are used at the microlevel. Depending on the texture geometry and film height, the Reynolds equation may become invalid. A second pocket effect occurs when the pocket is located in the moving surface. In mixed lubrication, fluid can become trapped inside a pocket and squeezed out when the pocket is running into an area with higher contact load. To include this effect, an additional source term that represents the average fluid inflow due to the deformation of the surface around the pocket is added to the Reynolds equation at macrolevel. The additional inflow is computed at microlevel by numerical solution of the surface deformation for a single pocket that is subject to a contact load. The pocket volume is a function of the contact pressure. It must be emphasized that before ready-to-use results can be presented, a large number of simulations to determine the flow factors and pressure gain as a function of the texture parameters and operating conditions have yet to be done. Before conclusions can be drawn, regarding the dominanant mechanism(s), the flow factors and pressure gain have to be added to the macrobearing model. In this paper, only a limited number of preliminary illustrative simulation results, calculating the flow factors for a single 2D texture geometry, are shown to give insight into the method.

A transient analysis of the textured journal bearing considering micro and macro cavitation during an engine cycle

2017 ◽  
Vol 231 (10) ◽  
pp. 1289-1306 ◽  
Author(s):  
Chunxing Gu ◽  
Xianghui Meng ◽  
Di Zhang ◽  
Youbai Xie
Keyword(s):  
Transient Analysis ◽  
Engine Speed ◽  
Statistical Approach ◽  
Journal Bearing ◽  
Operating Conditions ◽  
Deterministic Approach ◽  
Textured Surfaces ◽  
Potential Reduction ◽  
System A ◽  
Bearing System

This paper presents a transient analysis of the textured journal bearing system. A mass-conserving model is developed to consider the combined effects of the inter-asperity cavitation and the macroscopic cavitation between two rough textured surfaces. In this model, the inter-asperity cavitation induced by the roughness is considered by the statistical approach (the classic flow factor methodology), while the deterministic approach is used to deal with the macroscopic cavitation induced by textures and macroscopic geometry. Moreover, the system of discretized equations for this model is unconstrained by reformulating the cavitation conditions, which is in favor of improving the computational efficiency. Furthermore, based on the fully dynamic analysis, the present study examines the effect of different textures (dimple and groove) under the engine operating conditions. It is found that the position of journal center is changed according to the engine speed and then influences the potential reduction effects produced by texturing.

The Effect of Elastic Distortions on Journal Bearing Performance

1967 ◽  
Vol 89 (4) ◽  
pp. 409-415 ◽  
Author(s):  
J. O’Donoghue ◽  
D. K. Brighton ◽  
C. J. K. Hooke
Keyword(s):  
Exact Solution ◽  
Pressure Distribution ◽  
Elastic Deformation ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Wide Range ◽  
Constant Viscosity ◽  
Outside Diameter

This paper presents a solution to the problem of hydrodynamic lubrication of journal bearings taking into account the elastic distortions of the shaft and the bearing. The exact solution for determining the elastic deformation for a given pressure distribution around a bearing is given, together with the reiterative procedure adopted to find the pressure distribution which satisfies both the hydrodynamic and elastic requirements of the system. Results are given which have been derived for a material with a Poisson’s ratio of 0.28, but other values such as 0.33 do not incur substantial errors. The results can be applied to a wide range of operating conditions using the nondimensional group of terms suggested in the paper. The bearing is assumed to be infinite in length, and infinite in thickness. The latter assumption is shown to be valid for a particular case where the outside diameter of the bearing shell is 3.5 times the shaft diameter. A further assumption in the calculation is a condition of constant viscosity of the lubricant existing around the bearing.

Inertia and Shear-Thinning Effects on Bearing Behavior With Impulsive Loads

1994 ◽  
Vol 116 (3) ◽  
pp. 535-540 ◽  
Author(s):  
Benyebka Bou-Sai¨d ◽  
Pascal Ehret
Keyword(s):  
Journal Bearing ◽  
Shear Thinning ◽  
Industrial Applications ◽  
Operating Conditions ◽  
High Shear ◽  
Power Law Model ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Impulsive Loads ◽  
Bearing Behavior

The study of bearings subjected to impulsive loads have previously showed that inertia effects and surface accelerations play an important role in the bearing response. Although the lubricant was considered Newtonian, this assumption is no longer valid with modern lubricant. In industrial applications, mineral lubricants are added to several long soluble chains of polymer in order to conserve optimum properties under different operating conditions. The addition of these polymers results in the drop of viscosity under high shear-rate, in the range of 10−6–10−8s−1. This study presents a continuation of previous works. It examines the influence of both effects, the decrease in viscosity and the fluid inertia, in a journal bearing under impulsive loads. Using the power-law model, the results show important differences in shaft responses compared to the Newtonian cases. Furthermore, in high shear-thinning effects, a reduction of lubricant capacity to absorb sudden dynamic loads is observed.

Numerical Study of the Pressure Pattern in a Two-Dimensional Hybrid Journal Bearing Recess, Laminar, and Turbulent Flow Results

2003 ◽  
Vol 125 (2) ◽  
pp. 283-290 ◽  
Author(s):  
Mathieu Helene ◽  
Mihai Arghir ◽  
Jean Frene
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Turbulent Flows ◽  
Journal Bearing ◽  
Stokes Equations ◽  
Numerical Study ◽  
Operating Conditions ◽  
Two Dimensional ◽  
Pressure Pattern ◽  
Inertia Effects

The present work is a parametric study of the pressure pattern in a two-dimensional recess of a hybrid journal bearing (HJB). It is known that theoretical models of HJB are largely dependent on the recess pressure pattern especially for severe working conditions (high rotation speeds, shallow pockets, etc.). The difficulty is that the recess flow is dominated by the interaction of viscous and inertia forces and cannot be analyzed using a thin film model. The present analysis is based on the numerical resolution of the two-dimensional Navier-Stokes equations where only one recess is modeled (with the film lands and the supply region), the fluid being regarded as incompressible and isothermal. Both the laminar and the turbulent flow regimes are considered. The study is governed by two parameters, one related to the HJB operating conditions and the other related to the recess geometric characteristics. The first parameter is the ratio of the runner versus the supply Reynolds number, Rer/Res∈{0,1/4,1/2,1,4,8}. The supply Reynolds number is fixed at 100 for the laminar regime and at 5000 for the turbulent one. The second parameter is the ratio of the recess depth versus the film thickness. Six values of this ratio are considered, ranging from 4 (shallow recess) to 152 (deep recess). Detailed pressure patterns on the runner wall are presented in a systematic manner giving a clear insight of the flow effects intervening in the recess and of their mutual interaction. Some effects are explained by analyzing the recirculation zones inside the recess. It is also shown that for certain parameters turbulent flows have qualitatively similar effects as laminar ones but they can also have specific trends. In order to sustain this remark, the pressure variation at the recess downstream end is analyzed in the paper. Finally, the present results and specially the turbulent ones are intended to contribute to the understanding of viscous and inertia effects interactions in a recess flow and to represent a database in view of HJB theoretical modeling.

Structural Damping of Self-Acting Compliant Foil Journal Bearings

1994 ◽  
Vol 116 (1) ◽  
pp. 76-82 ◽  
Author(s):  
Hooshang Heshmat ◽  
C.-P. Roger Ku
Keyword(s):  
Journal Bearing ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Test Facility ◽  
Structural Stiffness ◽  
Structural Damping ◽  
Equivalent Viscous Damping ◽  
Compliant Surface ◽  
Wide Range ◽  
Dynamic Forces

This paper describes an experimental investigation into the dynamic characteristics of corrugated foil (bump foil) strips used in compliant surface foil journal bearings and dampers. In the experimental method described herein, a test facility with a journal supported by a compliant foil journal bearing was built. The nonrotating journal was driven by two shakers which were used to simulate dynamic forces acting on bump foil strips. The dynamic structural stiffness and equivalent viscous damping coefficients are calculated based on the experimental measurements for a wide range of operating conditions. The results are compared to the analytical predictions obtained by a theoretical model developed earlier.

Predicted Performance of a Tri-Taper Journal Bearing Including Turbulence and Misalignment Effects

1995 ◽  
Vol 209 (2) ◽  
pp. 85-97 ◽  
Author(s):  
D J Hargreaves
Keyword(s):  
Journal Bearing ◽  
Operating Conditions ◽  
Performance Characteristics ◽  
Inertia Effects ◽  
Performance Predictions ◽  
Manufacturing Tolerances ◽  
Journal Misalignment ◽  
Design Guidance

The performance predictions of a particular tri-taper journal bearing are shown to confirm known operating conditions. The importance of manufacturing tolerances on the resulting performance characteristics are highlighted. Design guidance for a family of these bearings including journal misalignment and lubricant inertia effects is also provided.

Sign in / Sign up

Export Citation Format

Share Document