The Effects of Geometric Irregularities of Journals on the Performance of Porous Bearings

1994 ◽  
Vol 208 (2) ◽  
pp. 141-145 ◽  
Author(s):  
T S Chennabasavan ◽  
R Raman
Keyword(s):  
Theoretical Analysis ◽  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Eccentricity Ratio ◽  
Attitude Angle ◽  
Load Carrying ◽  
Permeability Variation ◽  
Very High

In the theoretical analysis of porous bearings the journal has so far been assumed to be ideal, that is perfectly cylindrical. In the present analysis the geometric irregularities of the journal, such as circumferential undulations and barrel/bellmouth shapes, are taken into account. The permeability variation along the length of the bearing as found in commercial bearings has also been taken into account. The present analysis reveals that, at the critical Sommerfeld number, the friction is very low compared to the very high value for an ideal journal. The present analysis also reveals that the friction and the attitude angle are lower for any Sommerfeld number and that the load-carrying capacity is lower for any eccentricity ratio than that for an ideal journal.

STABILITY PROBLEMS OF STEEL‐CONCRETE MEMBERS COMPOSED OF HIGH‐STRENGTH MATERIALS

2010 ◽  
Vol 16 (3) ◽  
pp. 352-362 ◽  
Author(s):  
Zdeněk Kala ◽  
Libor Puklický ◽  
Abayomi Omishore ◽  
Marcela Karmazínová ◽  
Jindřich Melcher
Keyword(s):  
Theoretical Analysis ◽  
Experimental Research ◽  
Carrying Capacity ◽  
High Strength ◽  
Statistical Characteristics ◽  
Load Carrying Capacity ◽  
Limit States ◽  
Load Carrying ◽  
Geometrical Imperfections

The presented paper deals with the stochastic analysis of the ultimate limit states of steel‐concrete building members. The load carrying capacity of steel‐concrete columns, comprising of steel profiles encased in high strength concrete, in compression is analyzed. The first part of the paper lists assumptions for the determination of the theoretical load carrying capacity of the column. Principles of elasticity and plasticity are used to determine stresses in the concrete and steel sections. Statistical characteristics of input material and geometrical imperfections are listed. Results of the theoretical analysis are then compared with results of experimental research. Statistical characteristics of obtained results of the theoretical analysis were verified using statistical characteristics obtained from experimental research. Numerical simulation LHS and Monte Carlo methods, which take into account the influences of variability of input imperfections, were employed. The influence of the utilization of the plastic reserve in the determination of the load carrying capacity of the analysed strut is shown. The influence of the initial geometric imperfections of initial strut curvature on the load carrying capacity is also presented. Santrauka Straipsnyje pateikta plienbetonio pastatu elementu didžiausiu ribiniu būkliu stochastine analize, analizuojama plienbetonio kolonu, sudarytu iš plieniniu profiliuočiu, padengtu didelio stiprio betonu, laikomoji galia gniuždant. Pirmoje straipsnio dalyje išvardytos kolonos teorines laikomosios galios nustatymo prielaidos. Tamprumo ir plastiškumo principai taikyti itempiams betono ir plieno skerspjūviuose nustatyti. Nustatytos medžiagu ir geometriniu defektu statistines charakteristikos, teorines analizes rezultatai palyginti su eksperimentiniu tyrimu rezultatais. Teorines analizes metu gautu rezultatu statistines charakteristikos patikrintos taikant iš eksperimentiniu tyrimu gautus statistinius rodiklius. Pritaikytas skaitinis modeliavimas LHS ir Monte Karlo metodais, kurie ivertina pradiniu defektu kintamumo itaka. Parodyta plastiškumo atsargos naudojimo itaka, nustatant analizuojamojo statramsčio laikomaja galia, pateikta pradinio statramsčio išlinkio pirminiu geometriniu defektu itaka laikomajai galiai.

On Failure Problem of Gears Made From Very High Strength Steel

2011 ◽  
Author(s):  
Aizoh Kubo
Keyword(s):  
Carrying Capacity ◽  
High Strength Steel ◽  
High Surface ◽  
Surface Hardness ◽  
High Strength ◽  
Load Carrying Capacity ◽  
Edge Contact ◽  
Load Carrying ◽  
Tooth Form ◽  
Very High

Some typical examples of failure of gears made from very high strength steel are shown and its trigger and whose causes are discussed: Many of such failure are triggered by tooth side edge contact or tooth tip edge contact and meshing-in of the wear debris. The limit of validity of the traditional methods for load carrying capacity of gears exists in the fact that they are based on the theory of contact of tooth flanks that realize conjugate or almost conjugate action of gears. To be able to design reliable gears made from very high strength steel, a principle is shown that suggests a new method for tooth form modification and of longitudinal crowing modification to avoid such failure. Metallurgical problem of gear material and special heat treatment aiming high surface hardness is also discussed.

The Hybrid Isothermal Air Lubricated Journal Bearing

1979 ◽  
Vol 101 (4) ◽  
pp. 444-450 ◽  
Author(s):  
V. Kamala
Keyword(s):  
Comparative Study ◽  
Carrying Capacity ◽  
Journal Bearing ◽  
Order Perturbation ◽  
Load Carrying Capacity ◽  
Eccentricity Ratio ◽  
Small Eccentricity ◽  
First Order ◽  
Load Carrying ◽  
First Order Perturbation

This paper analyzes the load-carrying capacity of the hybrid air lubricated journal bearing. Assuming a small eccentricity ratio, a first order perturbation solution is obtained. The air is fed to the bearing through inherent restrictor with feeding holes distributed around the circumference in one, two, and three feeding planes (Fig. 1). The number of feeding holes in each plane is sufficiently large to permit the feeding planes being treated as the line sources. The results are given for the load-carrying capacity and the attitude angle. A comparative study is made of the three types of gas feeding arrangements.

Influence of Texture Portion and Dimple Area Density on the Tribological Characteristics of Dimple Textured Hydrodynamic Journal Bearing

2021 ◽  
Author(s):  
Nayab Rasool Syed ◽  
Sashindra Kumar Kakoty
Keyword(s):  
Tribological Properties ◽  
Carrying Capacity ◽  
Journal Bearing ◽  
Maximum Flow ◽  
Flow Coefficient ◽  
Load Carrying Capacity ◽  
Normal Surface ◽  
Area Density ◽  
Attitude Angle ◽  
Load Carrying

Abstract There is a growing interest towards the textured bearings. The normal surface texture has the shape of micro-dimples with preselected diameter, area density and depth. The use of different amount of texturing and dimple area density, can be an effective way to improve tribological properties of textured bearing. In the present study, the tribological properties, of the dimple textured journal bearing of L/D = 2, such as attitude angle, load carrying capacity, friction variable and flow coefficient are estimated for different texture portion and dimple area density. The computationally efficient Progressive mesh densification method is implemented for the numerical solution. The governing Reynolds equation is discretized with the finite difference scheme and then solved using Gauss Seidel method coupled with Successive over relaxation scheme. The numerical results show that the flow coefficient and attitude angle has been improved significantly with texture portion variation. Similarly, when the dimple area density is varied, there is significant improvement in flow coefficient and attitude angle resulting in the maximum flow coefficient at the dimple area density of 0.25 and minimum attitude angle, at the eccentricity ratios from 0.5 to 0.7, for the dimple area density of 0.20. However, the texture portion and dimple area density have no positive influence on the load carrying capacity and friction variable.

Dynamic stability analysis of noncircular two-lobe journal bearings with couple stress lubricant regime

2020 ◽  
pp. 135065012094551
Author(s):  
Mahdi Zare Mehrjardi
Keyword(s):  
Steady State ◽  
Carrying Capacity ◽  
Couple Stress ◽  
Journal Bearings ◽  
Lubricating Oil ◽  
Couple Stress Fluid ◽  
Load Carrying Capacity ◽  
Stress Parameter ◽  
Attitude Angle ◽  
Load Carrying

In this research, the steady state and dynamic performances of two-lobe noncircular journal bearings with couple stress lubricant are presented. The lubricating oil, containing additives and contaminants, is modeled as the couple stress fluid. The modified Reynolds equation is obtained using the couple stress lubrication theory and is then solved by finite element method as an efficient numerical technique. The steady-state characteristics of bearings, including the load carrying capacity and attitude angle, are determined for various values of the couple stress parameter. The results show that applying the couple stress fluid improves the efficiency of two-lobe bearings in terms of an increased load carrying capacity and reduced attitude angle. Also, the stability performance of the investigated bearings is studied using rotor motion equations based on linear and nonlinear dynamic methods. The results indicate that any increase in the lubricant couple stress parameter enhances the bearing ability to damp the rotor perturbations. In other words, by varying the lubricant from Newtonian oil to the couple stress type and upgrading its properties, the curves of the critical mass parameter and whirl frequency ratio have an increasing and decreasing trend, respectively. Based on the fourth-order Runge–Kutta method results, the dynamic trajectory of the rotor center in the bearing space changes with increasing the couple stress parameter from diverging disturbances and limits the cycle perturbations around the bearing center to converging oscillations to the static equilibrium point. Moreover, the effect of changing lubricant properties on the two-lobe bearing’s performance is more pronounced at higher values of the couple stress parameter, especially with an increase in the noncircularity of bearings’ geometry.

Maintenance-Free, Low Stick-Slip ELGOGLIDE® Plain Bearings for Industrial Applications

2005 ◽  
Author(s):  
Sergej Schwarz ◽  
Heinrich Nollek ◽  
Falk Breutinger ◽  
Max Schlar
Keyword(s):  
Carrying Capacity ◽  
Industrial Applications ◽  
High Load ◽  
Load Carrying Capacity ◽  
Brand Name ◽  
Stick Slip ◽  
New Development ◽  
Load Carrying ◽  
Long Life ◽  
Very High

In the following article, a new development from the Schaeffler Group Industrial will be presented in the ELGES maintenance-free plain bearing sector (brand name: ELGOGLIDE®). The bearings feature very smooth operation (low stick-slip) even in very unfavorable conditions. The friction coefficient is low and is only marginally dependent on the running velocity and the temperature. At the same time, the bearings feature a very high load carrying capacity and a long life. Application examples will be discussed and explained.

The Hydrostatic Gas Journal Bearing With Journal Rotation and Vibration

1964 ◽  
Vol 86 (2) ◽  
pp. 328-336 ◽  
Author(s):  
J. W. Lund
Keyword(s):  
Carrying Capacity ◽  
Journal Bearing ◽  
Load Carrying Capacity ◽  
Restricted Feeding ◽  
Eccentricity Ratio ◽  
Small Vibration ◽  
Small Eccentricity ◽  
First Order ◽  
Load Carrying ◽  
Gas Journal Bearing

This paper analyzes the load-carrying capacity of the externally pressurized gas journal bearing, including the effect of journal rotation and vibration. The analysis assumes small eccentricity ratio and small vibration amplitude such that a first-order perturbation solution is obtained. The gas is fed to the bearing through orifice-restricted feeding holes around the circumference in one or two feeding planes. The number of feeding holes is sufficiently large to permit treating the feeding planes as line sources. Results are given for the load-carrying capacity and the attitude angle.

scholarly journals Influence of viscosity variation on ferrofluid based long bearing

2022 ◽  
Vol 3 (1) ◽  
pp. 37-45
Author(s):  
Jimit Patel ◽  
◽  
G. M. Deheri ◽  
Keyword(s):  
Fluid Flow ◽  
Theoretical Analysis ◽  
Pressure Distribution ◽  
Magnetic Fluid ◽  
Carrying Capacity ◽  
Type Equation ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Viscosity Variation

This paper deals with a theoretical analysis on the effect of viscosity variation on a ferrofluid based long bearing. The model of Tipei considering viscosity variation is deployed here. The magnetic fluid flow is governed by Neuringer-Rosensweig model. The pressure distribution is obtained after solving the associated Reynolds type equation, which gives the load carrying capacity. The computed results indicate that the increased load carrying capacity owing to magnetization gets negligible help from the effect of viscosity variation.

Performance Analysis of the Flotation Cushion with Elastic Pressure Equalizing Groove for Aerostatic Slideway

2012 ◽  
Vol 152-154 ◽  
pp. 743-748 ◽  
Author(s):  
Jun An Zhang ◽  
Hao Dong ◽  
Fang Jie Ma ◽  
Bo Liu
Keyword(s):  
Performance Analysis ◽  
Theoretical Analysis ◽  
Governing Equation ◽  
Elastic Plate ◽  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Variable Section ◽  
New Type ◽  
Coupling Calculation

In order to improve stiffness of the flotation cushion, a new type of flotation cushion with variable-section pressure equalizing groove of elastic plate for aerostatic slideway was designed. Gas film pressure distribution and load carrying capacity of this flotation cushion was studied through theoretical analysis. The grid was generated by taking advantage of overlapping stitching technique. By using the coupling calculation of the gas lubrication governing equation and elastic deformation of thin plate governing equation, the load carrying capacity and stiffness of the new flotation cushion were obtained. Some experiments were made to verify the result of theoretical calculation. The experimental results show that the stiffness of new flotation cushion is much higher than conventional flotation cushion.This new flotation cushion has a wider application space.

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