Dynamic Behavior of Pure Squeeze Films in Narrow Porous Bearings

1974 ◽  
Vol 96 (3) ◽  
pp. 361-364 ◽  
Author(s):  
P. R. K. Murti
Keyword(s):  
Dynamic Behavior ◽  
Cyclic Load ◽  
Journal Bearing ◽  
Load Capacity ◽  
Squeeze Film ◽  
Closed Form Expression ◽  
Cyclic Loads ◽  
Eccentricity Ratio ◽  
Form Expression ◽  
Bearing Material

The dynamic behavior of squeeze film in a narrow porous journal bearing under a cyclic load is analyzed. A thin-walled bearing with a nonrotating journal is considered and a closed form expression for the pressure distribution is derived. The locus of the journal center is found by numerical methods and it is established with an example that actual contact between the journal and bearing can be avoided by appropriate design of the bearing. Consequently, it is proved that pure squeeze films have a load capacity only under cyclic loads. The analysis also reveals that the permeability of the bearing material and the wall thickness of the bearing influence significantly the operating eccentricity ratio.

Influence of different flow regimes on the performance characteristics of a four-pad hydrostatic squeeze film damper loaded between pads

2019 ◽  
Vol 71 (3) ◽  
pp. 440-446
Author(s):  
Amina Nemchi ◽  
Ahmed Bouzidane ◽  
Aboubakeur Benariba ◽  
Hicham Aboshighiba
Keyword(s):  
Turbulent Flow ◽  
Load Capacity ◽  
Flow Regimes ◽  
Performance Characteristics ◽  
Squeeze Film ◽  
Eccentricity Ratio ◽  
Flow Conditions ◽  
Content Type ◽  
Turbulent Flow Regime ◽  
Squeeze Film Dampers

Purpose The purpose of this paper is to study the influence of different flow regimes on the dynamic characteristics of four-pad hydrostatic squeeze film dampers (SFDs) loaded between pads. Design/methodology/approach A numerical model based on Constantinescu’s turbulent lubrication theory using the finite difference method has been developed and presented to study the effect of eccentricity ratio on the performance characteristics of four-pad hydrostatic SFDs under different flow regimes. Findings It was found that the influence of turbulent flow on the dimensionless damping of four-pad hydrostatic SFDs appears to be essentially controlled by the eccentricity ratio. It was also found that the laminar flow presents higher values of load capacity compared to bearings operating under turbulent flow conditions. Originality/value In fact, the results obtained show that the journal bearing performances are significantly influenced by the turbulent flow regime. The study is expected to be useful to bearing designers.

An Alternative Hydrodynamic Force Model for Finite Bearings

2009 ◽  
Author(s):  
Yaser Bastani ◽  
Marcio de Queiroz
Keyword(s):  
Reynolds Equation ◽  
Hydrodynamic Force ◽  
Journal Bearings ◽  
Closed Form Expression ◽  
Force Model ◽  
Eccentricity Ratio ◽  
Form Expression ◽  
Order Polynomial ◽  
Polynomial Models ◽  
Bearing System

A method for determining a closed-form expression for the hydrodynamic forces in finite plain journal bearings is introduced. The method is based on applying correction functions to the force models of the infinitely-long (IL) or infinitely-short (IS) bearing approximation. The correction functions are derived by modeling the ratio between the forces from the numerical integration of the two-dimensional Reynolds equation and the forces from either the IL or IS bearing approximation. Low-order polynomial models, dependent on the eccentricity ratio and aspect ratio, are used for the correction functions. The models are shown to outperform the standard limiting approximations in the steady-state analysis of the bearing system under static loading.

Numerical Investigation on the Mixed Lubrication Performance of Water-Lubricated Coupled Journal and Thrust Bearings

2019 ◽  
Author(s):  
Yanfeng Han ◽  
Guo Xiang ◽  
Jiaxu Wang
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Thrust Bearing ◽  
Journal Bearing ◽  
Load Capacity ◽  
Hydrodynamic Pressure ◽  
Mixed Lubrication ◽  
Eccentricity Ratio ◽  
Thrust Bearings ◽  
Lubrication Performance

Abstract The mixed lubrication performance of water-lubricated coupled journal and thrust bearing (simplified as coupled bearing) is investigated by a developed numerical model. To ensure the continuity of hydrodynamic pressure and flow at the common boundary between the journal and thrust bearing, the conformal transformation is introduced to unify the solution domain of the Reynolds equation. In the presented study, the coupled effects between the journal and thrust bearing are discussed. The effects of the thrust bearing geometric film thickness on the mixed lubrication performance, including the load capacity, contact load and friction coefficient, of the journal bearing are investigated. And the effects of the journal bearing eccentricity ratio on the mixed lubrication performance of the thrust bearing are also investigated. The simulated results indicate the mutual effects between the journal and thrust bearing cannot be ignored in the coupled bearing system. The increasing thrust bearing geometric film thickness generates a decrease in load capacity of journal bearing. There exists an optimal eccentricity ratio of journal bearing that yields the minimum friction coefficient of the thrust bearing.

On the Load Capacity of the MHD Journal Bearing

1968 ◽  
Vol 90 (1) ◽  
pp. 139-144 ◽  
Author(s):  
S. J. Dudzinsky ◽  
F. J. Young ◽  
W. F. Hughes
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Journal Bearing ◽  
Hartmann Number ◽  
Load Capacity ◽  
External Source ◽  
Diameter Ratio ◽  
Experimental Results ◽  
Eccentricity Ratio ◽  
Applied Current

An analysis and experimental results are presented for a magnetohydrodynamic partial journal bearing using a liquid metal lubricant. An external magnetic field is applied axially along the journal, and current is permitted to flow between the journal and bearing. The analysis shows that increased load capacity can be achieved by supplying current from an external source. In addition, the analysis reveals the existence of an optimum Hartmann number at which the load capacity peaks for a given applied current. This optimum value is about 5 for a dimensionless current I¯ = −5 applied to a bearing with a width/diameter ratio of 1 and an eccentricity ratio of 0.6. Experimental results which demonstrate the increase in load capacity resulting from an externally applied current are presented graphically and compared with the theory.

The Load Capacity of Short Journal Bearings With Oscillating Effective Speed

1964 ◽  
Vol 86 (2) ◽  
pp. 348-353 ◽  
Author(s):  
B. K. Gupta ◽  
R. M. Phelan
Keyword(s):  
Significant Contribution ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Numerical Solutions ◽  
Load Capacity ◽  
Journal Bearings ◽  
Squeeze Film ◽  
Major Conclusion ◽  
Angular Velocities ◽  
Effective Speed

The development of the Reynolds equation for the general case of dynamically loaded journal bearings is extended to include the concept of an effective speed that combines in one term the angular velocities of the journal, bearing, and load. Numerical solutions for the short-bearing approximation are presented for the case of an oscillating effective speed and a load that is constant or varying sinusoidally. Results are compared with available experimental data. The major conclusion is that for those cases involving an oscillating effective speed and a reversing load, the only significant contribution to load capacity comes from the squeeze film and the wedge film can safely be ignored when designing such bearings.

Study on Load Capacity and Dynamic Characteristics of the Wave Bearing at Infinite Compressibility Number

2014 ◽  
Author(s):  
Baisong Yang ◽  
Haipeng Geng ◽  
Jian Zhou ◽  
Lie Yu ◽  
Shemiao Qi ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Journal Bearing ◽  
Load Capacity ◽  
Dynamic Stiffness ◽  
Computational Method ◽  
Wave Number ◽  
Algebraic Equations ◽  
Eccentricity Ratio ◽  
Operation Speed ◽  
Stiffness And Damping

The wave bearing developed by Dimofte in the 1990’s features a continuous wave profile and presents numerous advantages compared to plain journal bearings. One of the main advantages of the wave bearing is that it has a higher degree of stability than the plain journal bearing and this load capacity is close to the load capacity of the plain journal bearing. Predicting these coefficients for the wave bearing with high bearing numbers is difficult, although there are many studies on the aerodynamic bearing. This paper presents an analytical method for calculating the limiting values of load capacity, dynamic stiffness and damping coefficients of the wave bearing for compressible fluids by simplifying the compressible Reynolds equation at high journal operation speed. A computational method is submitted which is derived from simple algebraic equations combined with infinitesimal perturbation method. The limiting characters of the wave bearing are compared with the plain journal bearing for all eccentricity ratios. Special emphasis is placed on investigating the effects of wave number, wave eccentricity ratio and wave starting angle on the limiting characteristics. Numerical results obtained indicate that the load capacity and stiffness of the wave bearing is better than the plain journal bearing at the same eccentricity ratio.

scholarly journals Comparison of Safety Factor Values for Soderberg and DIN 743 Fatigue Analyses

2021 ◽  
Vol 7 (2) ◽  
pp. 11-21
Author(s):  
Beatriz Henriques ◽  
Mariana Carvalho ◽  
Sérgio Tavares ◽  
Paulo De Castro
Keyword(s):  
Safety Factor ◽  
Cyclic Load ◽  
High Cycle Fatigue ◽  
Load Capacity ◽  
Cyclic Loads ◽  
Correction Factors ◽  
Fatigue Design ◽  
Different Types ◽  
Machine Elements ◽  
Critical Aspects

Fatigue phenomena are critical aspects of the life cycle of many components or structures. The variety of cyclic load situations led to the emergence, throughout the years, of different types of studies as high-cycle, low-cycle, and fatigue crack growth, among others. Particularly for machine elements, high-cycle fatigue situations are the more frequent, and simplified approaches taking into account the Soderberg criterion have been commonly used. Meanwhile, the German Institute for Standardization put forward a procedure for fatigue design of shafts, DIN 743, based on the use of Smith diagrams and considering separately the safety factor (SF) for static and for cyclic loads. The present paper compares Soderberg and DIN 743 approaches, focusing on SF obtained when load capacity is calculated considering equal correction factors in both methods. A set of representative situations was defined, and the comparison was carried out parametrically using Matlab software. The SF values of the Soderberg method were always found to be lower than those of DIN 743, indicating that the Soderberg method is more conservative than DIN 743.

Theory and Experiments of Squeeze-Film Gas Bearings: Part 1—Cylindrical Journal Bearing

1966 ◽  
Vol 88 (1) ◽  
pp. 191-198 ◽  
Author(s):  
C. H. T. Pan ◽  
S. B. Malanoski ◽  
P. H. Broussard ◽  
J. L. Burch
Keyword(s):  
Experimental Data ◽  
Journal Bearing ◽  
Approximate Analytical Solution ◽  
Load Capacity ◽  
Squeeze Film ◽  
Radial Load ◽  
Radial Stiffness ◽  
Theoretical Predictions ◽  
Gas Journal Bearing ◽  
Theory And Experiments

An asymptotic analysis for the cylindrical squeeze-film gas journal bearing has been formulated. An approximate analytical solution is presented. Load-deflection experiments have been performed on a double-film, squeeze-film gas journal bearing. The experimental data confirm the theoretical predictions. Design curves are given for the steady-state radial load capacity and radial stiffness of the cylindrical gas journal bearing.

On the Analytical Evaluation of the Lubricant Pressure in the Finite Journal Bearing

2012 ◽  
Author(s):  
Athanasios Chasalevris ◽  
Dimitris Sfyris
Keyword(s):  
Analytical Solution ◽  
Pressure Distribution ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Numerical Solutions ◽  
Load Capacity ◽  
Separation Of Variables ◽  
Closed Form Expression ◽  
Linear Ordinary Differential Equations ◽  
Definition Of

The Reynolds equation for the pressure distribution of the lubricant in a journal bearing with finite length is solved analytically. Using the method of the separation of variables in an additive and in a multiplicative form, a set of particular solutions of the Reynolds equation is added in the general solution of the homogenous Reynolds equation and a closed form expression for the definition of the lubricant pressure is presented. The Reynolds equation is split in four linear ordinary differential equations of second order with non constant coefficients and together with the boundary conditions they form four Sturm-Liouville problems with the three of them to have direct forms of solution and one of them to be confronted using the method of power series. The mathematical procedure is presented up to the point that the application of the boundaries for the pressure distribution yields the final definition of the solution with the calculation of the constants. The current work gives in detail the mathematical path with which the analytical solution is derived, and it ends with the pressure evaluation and a comparison with past numerical solutions and an approximate analytical solution for a finite bearing. Also the parameters of primary interest to the bearing designer, such as load capacity, attitude angle, and stiffness and damping coefficients are evaluated and compared with numerical results.

Determination of the Integration Constant for Squeeze Films in Infinitely Long Journal Bearings

1970 ◽  
Vol 92 (1) ◽  
pp. 179-180
Author(s):  
D. C. Kuzma
Keyword(s):  
Arbitrary Constant ◽  
Journal Bearing ◽  
Load Capacity ◽  
Journal Bearings ◽  
Integration Constant ◽  
Squeeze Film ◽  
Positive Pressure ◽  
Limiting Case

The complete film solution for the squeeze film in an infinitely long journal bearing contains an arbitrary constant. When only positive pressure regions are retained, this constant influences the load capacity. Several different values have been used for this constant. Its value is determined here so that the infinitely long journal bearing is the limiting case of the finite journal bearing.

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