A Study of the Oil-Lubricated Herringbone-Grooved Journal Bearing—Part 1: Numerical Analysis

1996 ◽  
Vol 118 (4) ◽  
pp. 906-911 ◽  
Author(s):  
Kyungphil Kang ◽  
Yoonchul Rhim ◽  
Kiro Sung
Keyword(s):  
Journal Bearing ◽  
Numerical Study ◽  
Radial Force ◽  
Rectangular Profile ◽  
Governing Differential Equation ◽  
Optimal Values ◽  
The Stability ◽  
Stiffness And Damping ◽  
Optimal Configurations ◽  
Bearing Part

A numerical study of the oil-lubricated herringbone-grooved journal bearing is presented for the case of eight circular-profile grooves on the sleeve surface. The governing differential equation derived from the mass balance is solved by using the finite difference method. Some of the groove geometries are constrained because of the groove forming processes. Optimal values for various bearing parameters are obtained to maximize the radial force and to improve the stability characteristics. Results are compared with the plain and rectangular-profile grooved journal bearings. Radial force, attitude angle, stiffness and damping coefficients, and stability map are given for optimal configurations.

A Variable Viscosity Approach for the Analysis of Steady State and Dynamic Characteristics of Two-Lobe Journal Bearing With TiO2 Based Nanolubricant

2017 ◽  
Author(s):  
Ashutosh Kumar ◽  
Sashindra Kumar Kakoty
Keyword(s):  
Steady State ◽  
Dynamic Characteristics ◽  
Journal Bearing ◽  
Volume Fraction ◽  
Variable Viscosity ◽  
Flow Coefficient ◽  
Viscosity Model ◽  
Nano Lubricant ◽  
The Stability ◽  
Stiffness And Damping

Steady-state and dynamic characteristics of two-lobe journal bearing, operating on TiO2 based Nano-lubricant has been obtained. The effective viscosity is obtained by using Krieger-Dougherty viscosity model for a given volume fraction of nanoparticle in the base fluid. Various bearing performance characteristics are then obtained by solving modified Reynolds equation for variable viscosity model and couple stress model. The stiffness and damping coefficients are also determined for various values of the volume fraction of the nanoparticle in the nanofluid. Results reveal that load carrying capacity and flow coefficient increase whereas friction variable decreases without affecting the stability condition of two-lobe journal bearing operating on TiO2 based nanolubricant. On the other hand attitude angle and dynamic coefficients remains constant for all the values of volume fraction of nanoparticle.

Development of Herringbon-Grooved Aerodynamic Journal Bearing Systems for Ultra-High-Speed Rotations

2015 ◽  
Vol 656-657 ◽  
pp. 652-657 ◽  
Author(s):  
Norifumi Miyanaga ◽  
Jun Tomioka
Keyword(s):  
Rotational Speed ◽  
High Speed ◽  
Journal Bearing ◽  
Damping Properties ◽  
Shaft Rotation ◽  
Ultra High Speed ◽  
The Difference ◽  
The Stability ◽  
Stiffness And Damping ◽  
Bearing System

It is absolutely important for ultra-compact rotational machineries to achieve sable shaft rotation at ultra-high-speed. This paper discussed herringbone-grooved aerodynamic journal bearing systems developed for the purpose. In this system, the bearings are supported by rubber-O-rings for accurate and stable operations. To grasp the possibility for stabilization, two types of O-rings with different stiffness and damping properties under bearing supporting were tested in the experiment. As the results, the bearing system demonstrated the maximum rotational speed over 460,000 rpm without unstable phenomenon called whirl. However, the difference in rubber O-rings definitely affected the stability of the bearing system.

Stability, Load Capacity, Stiffness, and Damping Advantages of the Double Pocket Journal Bearing

1985 ◽  
Vol 107 (1) ◽  
pp. 53-58
Author(s):  
J. C. Nicholas
Keyword(s):  
Journal Bearing ◽  
Load Capacity ◽  
Load Carrying Capacity ◽  
Rigid Rotor ◽  
Instability Problem ◽  
Oil Whirl ◽  
Load Carrying ◽  
Bearing Design ◽  
The Stability ◽  
Stiffness And Damping

The double pocket bearing design is discussed and compared to the plain three axial groove bearing. Rigid rotor stability, load capacity, and stiffness and damping curves are shown for the two bearing designs illustrating the stability and load capacity advantages of the double pocket bearing. Results show that placing double opposing stepped pockets in the top pads of a three axial groove bearing is a simple, inexpensive, expedient modification that is effective in suppressing oil whirl instability. Furthermore, the bottom plain pad retains the load carrying capacity of the original three axial groove design. Frequency spectrums substantiating the stabilizing ability of the double pocket design are shown for a test stand instability problem.

scholarly journals Dynamic behaviour and stability analysis of a compensated aerostatic pad

2021 ◽  
Vol 312 ◽  
pp. 05003
Author(s):  
Federico Colombo ◽  
Luigi Lentini ◽  
Terenziano Raparelli ◽  
Andrea Trivella ◽  
Vladimir Viktorov
Keyword(s):  
Dynamic Behaviour ◽  
Numerical Study ◽  
Dynamic Performance ◽  
Low Friction ◽  
Lumped Model ◽  
Positioning Systems ◽  
Diaphragm Valve ◽  
Bearing Stiffness ◽  
The Stability ◽  
Stiffness And Damping

Thanks to their low friction, aerostatic pads have important applications in precision positioning systems and linear guides. A simple and cheap solution to increase the static stiffness of aerostatic pads is to add a proper designed pneumatic valve to regulate the air flow supplied to the bearing. However, integrating aerostatic pads with additional devices can reduce its dynamic performance. This paper presents a numerical study on the dynamic behaviour and stability a commercial aerostatic pad controlled by a custom-built diaphragm valve. The bearing performance is studied by means of a lumped parameters model. Air bearing stiffness and damping are analysed in the frequency domain. Subsequently, the lumped model is linearized to investigate the stability of the system by means of Routh-Hurwitz method. The performance of the controlled air pad is compared to that of a simple commercial air pad.

Evaluation of Dynamic Coefficients of a Two-Lobe Journal Bearing Using an Electrical Analogy Approach

1996 ◽  
Vol 118 (3) ◽  
pp. 657-662 ◽  
Author(s):  
Har Prashad
Keyword(s):  
Journal Bearing ◽  
Operating Conditions ◽  
Dynamic Coefficients ◽  
Electrical Analogy ◽  
Dimensional Parameters ◽  
Capacitive Reactance ◽  
Hydrodynamic Journal Bearing ◽  
The Stability ◽  
Stability Regime ◽  
Stiffness And Damping

A theoretical approach to evaluating capacitance, resistance, capacitive reactance, and impedance of the lower and upper lobes of a two-lobe elliptical hydrodynamic journal bearing under various operating conditions is developed. It is established that the change in capacitance and resistance with the change in eccentricity ratios is nonlinear. The capacitance and resistance, thus determined, are correlated with the dynamic coefficients of bearings using an electrical analogy. It is found that the stiffness and damping coefficients are higher for two-lobe bearings as compared to those of cylindrical bearings having identical dimensional parameters and operating under similar conditions. The analysis may have the potential to diagnose the stability regime of a bearing through the bearing’s electrical parameters. The electrical analogy may be a useful alternative to conventional techniques.

Finite Journal Bearing With Nonlinear Stiffness and Damping. Part 2: Stability Analysis

1982 ◽  
Vol 104 (2) ◽  
pp. 406-411 ◽  
Author(s):  
E. Hashish ◽  
T. S. Sankar ◽  
M. O. M. Osman
Keyword(s):  
Stability Analysis ◽  
Journal Bearing ◽  
Linear Equations ◽  
Orbital Stability ◽  
Nonlinear Stiffness ◽  
Stability Behavior ◽  
Supply Pressure ◽  
The Stability ◽  
Stiffness And Damping ◽  
High Possibility

Stability analysis is performed on the linearized as well as the actual nonlinear finite bearing equations using the improved mathematical models for the hydrodynamic forces that are presented in Part I of this investigation. The results of the analysis using the linear equations show a significant trend, different from previous investigation, with respect to different L/d ratios and therefore can be considered as modified stability curves for the finite bearing. The nonlinear analysis, based on numerical integration of the equation of motion, is carried out for the commonly used L/d = 1. Details on the stability behavior of the finite bearing are established, including the orbital stability regions. It is also found that under certain light loading conditions, the supply pressure can introduce a high possibility of orbital stability to the system.

scholarly journals Experimental Stability Study on Herringbone-Microgrooved Journal Bearing in an Impeller-Spindle

2012 ◽  
Vol 28 (1) ◽  
pp. 123-133 ◽  
Author(s):  
B.-H. Chang ◽  
P.-H. Chen ◽  
D.-S. Lee
Keyword(s):  
Static Load ◽  
Journal Bearing ◽  
Stability Study ◽  
Experimental Device ◽  
Eccentricity Ratio ◽  
Tablet Pcs ◽  
Damping Coefficients ◽  
The Stability ◽  
Stiffness And Damping ◽  
Stability Results

ABSTRACTThe reliability of the impeller-spindle with respect to the effects of abnormal vibrations and noises is relative to the whirl rotation in notebook (NB) computers, all-in-one (AIO) desktop systems, and tablet PCs. This study experimentally investigates the stability of a herringbone-microgrooved journal bearing in an impeller-spindle under static radial forces.The experimental device operated at 2700, 3600, 4200, and 4900rpm, with a static load ranging from 0.4, 0.8, and 1.6N. The experiment obtained the stiffness and damping coefficients, and the study involved analyzing the stability. Results show that the dimensionless threshold speed of rotation decreased as the Sommerfeld number increased. The proposed impeller-spindle is stable when the Sommerfeld number is less than 59, indicating that the impeller-spindle should not operate at an eccentricity ratio below 0.18.

Buckling of Circular Cylindrical Shells Using a Displacement Function

1974 ◽  
Vol 96 (4) ◽  
pp. 1322-1327
Author(s):  
Shun Cheng ◽  
C. K. Chang
Keyword(s):  
Boundary Conditions ◽  
Axial Compression ◽  
Cylindrical Shells ◽  
External Pressure ◽  
Displacement Function ◽  
Combined Loading ◽  
Trial Solution ◽  
Governing Differential Equation ◽  
Circular Cylindrical Shells ◽  
The Stability

The buckling problem of circular cylindrical shells under axial compression, external pressure, and torsion is investigated using a displacement function φ. A governing differential equation for the stability of thin cylindrical shells under combined loading of axial compression, external pressure, and torsion is derived. A method for the solutions of this equation is also presented. The advantage in using the present equation over the customary three differential equations for displacements is that only one trial solution is needed in solving the buckling problems as shown in the paper. Four possible combinations of boundary conditions for a simply supported edge are treated. The case of a cylinder under axial compression is carried out in detail. For two types of simple supported boundary conditions, SS1 and SS2, the minimum critical axial buckling stress is found to be 43.5 percent of the well-known classical value Eh/R3(1−ν2) against the 50 percent of the classical value presently known.

scholarly journals Thermoelastic analysis of FGM hollow cylinder for variable parameters and temperature distributions using FEM

2020 ◽  
Vol 9 (1) ◽  
pp. 256-264
Author(s):  
Dinkar Sharma ◽  
Ramandeep Kaur
Keyword(s):  
Stress Field ◽  
Hollow Cylinder ◽  
Numerical Study ◽  
Axial Stress ◽  
Circumferential Stress ◽  
Functionally Graded ◽  
Gradient Index ◽  
Variable Parameters ◽  
Graded Material ◽  
Governing Differential Equation

AbstractThis paper presents, numerical study of stress field in functionally graded material (FGM) hollow cylinder by using finite element method (FEM). The FGM cylinder is subjected to internal pressure and uniform heat generation. Thermoelastic material properties of FGM cylinder are assumed to vary along radius of cylinder as an exponential function of radius. The governing differential equation is solved numerically by FEM for isotropic and anistropic hollow cylinder. Additionally, the effect of material gradient index (β) on normalized radial stresses, normalized circumferential stress and normalized axial stress are evaluated and shown graphically. The behaviour of stress versus normalized radius of cylinder is plotted for different values of Poisson’s ratio and temperature. The graphical results shown that stress field in FGM cylinder is influenced by some of above mentioned parameters.

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