Stability of Rough Journal Bearings Using Nonlinear Transient Method

The stability of rigid rotors supported on finite oil rough journal bearings has been investigated using nonlinear transient method. The effect of various surface roughness parameters, viz., composite surface roughness, roughness orientation pattern, variance ratio on the stability is presented in the form of journal center trajectories. Although the stability is affected marginally with the increase in composite roughness, the variation is quite significant when the shear flow factor comes into the picture.

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Stability of a Rigid Rotor Supported on Rough Oil Journal Bearings

Journal of Tribology ◽

10.1115/1.2920233 ◽

1990 ◽

Vol 112 (1) ◽

pp. 73-77 ◽

Cited By ~ 12

Author(s):

B. C. Majumdar ◽

M. K. Ghosh

Keyword(s):

Surface Roughness ◽

Journal Bearings ◽

Variance Ratio ◽

Rigid Rotor ◽

Roughness Parameters ◽

Roughness Effect ◽

Composite Surface ◽

The Stability ◽

Orientation Pattern ◽

Rigid Rotors

This investigation deals with the stability of rigid rotors supported on finite rough oil journal bearings using perturbation method. The effect of various surface roughness parameters, viz., composite surface roughness, roughness orientation pattern and variance ratio on the stability has been studied. In general, surface roughness effect when incorporated into the analysis does not show a significant change in the stability for surfaces having same roughness structure. However, the effect of variance ratio (i.e., surfaces having different roughness structure) on stability is quite marked.

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Stability Analysis of Two-Layered Finite Hydrodynamic Porous Journal Bearing Using Linear and Nonlinear Transient Method

Volume 1: 21st Biennial Conference on Mechanical Vibration and Noise, Parts A, B, and C ◽

10.1115/detc2007-34416 ◽

2007 ◽

Author(s):

S. K. Kakoty ◽

S. K. Laha ◽

P. Mallik

Keyword(s):

Journal Bearing ◽

Journal Bearings ◽

Operating Conditions ◽

System Stability ◽

Rigid Rotor ◽

Transient Method ◽

Porous Bearing ◽

Nonlinear Transient ◽

Linear And Nonlinear ◽

The Stability

A theoretical analysis has been carried out to determine the stability of rigid rotor supported on two symmetrical finite two-layered porous oil journal bearings. The stability curves have been drawn for different eccentricity ratios and Sommerfeld numbers. The effect of bearing feeding parameter, L/D ratio on the stability is also investigated. This paper also deals with a theoretical investigation of stability using a non-linear transient method. This analysis gives the journal centre locus and from this the system stability can be determined. With the help of graphics, several trajectories of the journal centre have been obtained for different operating conditions. Finally a comparison between single-layered porous bearing and the two-layered porous bearing is presented here.

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Non-linear Transient Analysis of Submerged Oil Journal Bearings Considering Surface Roughness and Thermal Effects

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1243/pime_proc_1995_209_405_02 ◽

1995 ◽

Vol 209 (1) ◽

pp. 53-61 ◽

Cited By ~ 13

Author(s):

J Ramesh ◽

B C Majumdar ◽

N S Rao

Keyword(s):

Surface Roughness ◽

Transient Analysis ◽

Constant Load ◽

Journal Bearings ◽

Roughness Effects ◽

Periodic Load ◽

Composite Surface ◽

Non Linear ◽

The Stability ◽

Rotating Load

A time-transient non-linear analysis has been carried out to study the influence of surface roughness and viscosity-temperature dependency on stability of a submerged oil journal bearing. The average Reynolds equation has been solved simultaneously along with the energy equation and heat-transfer equation in bush and shaft. The cavitation model, proposed by Kicinski along the lines of Jacobsson-Floberg theory, has been modified to account for the surface roughness effects. The effect of various surface roughness parameters, such as the composite surface roughness, roughness orientation pattern and variance ratio, on the stability has been studied. The non-linear transient analysis of submerged oil journal bearings under (a) a unidirectional constant load, (b) a unidirectional periodic load and (c) a variable rotating load is performed.

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Comparison Between Linear and Nonlinear Transient Analysis Techniques to Find the Stability of a Rigid Rotor

Journal of Tribology ◽

10.1115/1.2833802 ◽

1999 ◽

Vol 121 (1) ◽

pp. 198-201 ◽

Cited By ~ 4

Author(s):

Ram Turaga ◽

A. S. Sekhar ◽

B. C. Majumdar

Keyword(s):

Transient Analysis ◽

Stability Limit ◽

Journal Bearings ◽

Quantitative Comparison ◽

Rigid Rotor ◽

Analysis Techniques ◽

Analysis Technique ◽

Nonlinear Transient ◽

Nonlinear Transient Analysis ◽

The Stability

The subsynchronous whirl stability limit of a rigid rotor supported on two symmetrical finite journal bearings has been studied using the linearised perturbation method and the nonlinear transient analysis technique. A quantitative comparison for journal bearings with different l/d ratios has been provided.

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On the stability of vertical axis rigid rotors running in pivoted pad journal bearings

Wear ◽

10.1016/0043-1648(76)90114-9 ◽

1976 ◽

Vol 36 (3) ◽

pp. 379-386

Author(s):

C. Ettles

Keyword(s):

Vertical Axis ◽

Journal Bearings ◽

The Stability ◽

Rigid Rotors

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Stability and Transient Characteristics of Four Multilobe Journal Bearing Configurations

Journal of Lubrication Technology ◽

10.1115/1.3251514 ◽

1980 ◽

Vol 102 (3) ◽

pp. 291-298 ◽

Cited By ~ 56

Author(s):

D. F. Li ◽

K. C. Choy ◽

P. E. Allaire

Keyword(s):

Transient Analysis ◽

Journal Bearing ◽

Journal Bearings ◽

Rigid Rotor ◽

Frequency Content ◽

Stability Threshold ◽

Fast Fourier Transform Analysis ◽

Linearized Stability ◽

Nonlinear Transient ◽

The Stability

Multilobe journal bearings are often used to improve the stability response of rotating machinery. Such machines operate near the stability threshold of the bearing-rotor system. This work determines the linearized stability threshold of four multilobe journal bearings: elliptical, offset elliptical, three lobe, and four lobe. A nonlinear transient analysis of a rigid rotor in each of these bearings is carried out above and below the threshold speed. Shaft orbits and bearing forces are calculated. A numerical fast Fourier transform analysis is used to obtain the frequency content of the nonlinear orbit.

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Nonlinear transient response of rough symmetric two lobe hole entry hybrid journal bearing system

Journal of Vibration and Control ◽

10.1177/1077546315575831 ◽

2016 ◽

Vol 23 (2) ◽

pp. 190-219 ◽

Cited By ~ 1

Author(s):

Satish C Sharma ◽

Prashant B Kushare

Keyword(s):

Surface Roughness ◽

Transient Response ◽

Journal Bearing ◽

Equations Of Motion ◽

Point Of View ◽

Stability Point ◽

Nonlinear Transient ◽

The Stability ◽

Bearing System ◽

Nonlinear Transient Response

The present paper describes the effect of surface roughness orientation pattern on the nonlinear transient response of symmetric two lobe capillary compensated hole entry hybrid journal bearing. Nonlinear equations of motion have been solved with the Runge-Kutta method. The stability of the journal bearing system has been studied by obtaining the journal center motion trajectories. The results of the study reveal that the surface roughness pattern significantly changes the stability of capillary compensated two lobe hole entry hybrid journal bearing. Hence, from the bearing stability point of view, a proper selection of the surface roughness pattern and bearing geometry is essential.

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Evaluating Surface Roughness From Contact Vibrations

Journal of Tribology ◽

10.1115/1.2830607 ◽

1995 ◽

Vol 117 (1) ◽

pp. 60-64 ◽

Cited By ~ 10

Author(s):

Daniel P. Hess ◽

Nitish J. Wagh

Keyword(s):

Surface Roughness ◽

Contact Dynamics ◽

Roughness Parameters ◽

Average Roughness ◽

Composite Surface ◽

Normal Contact ◽

Roughness Model ◽

Contact Frequency ◽

The Relationship ◽

Theory And Experiments

This paper examines the relationship between the contact dynamics and the composite surface roughness of two bodies in planar contact. Measurements of the natural contact frequency are obtained for a range of surface roughness levels and normal loads from an apparatus which isolates the contact dynamics of two steel blocks from all other system dynamics. The normal contact dynamics of the contacting components are modeled with a single-degree-of-freedom system which incorporates the Greenwood and Williamson surface roughness model. Analytical and empirical expressions relating the normal natural contact frequency and roughness parameters, such as the standard deviation of asperity heights and the average roughness value, are developed. Both theory and experiments show that the contact frequency increases with a decrease in the composite roughness and vice versa; a power law relation between the contact frequency and the roughness parameters is found in most cases. The results of this work indicate that it may be possible to use contact vibration as a means for assessing or monitoring composite roughness parameters of surfaces in contact.

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Assessing the Functional Properties of TiZr Nanotubular Structures for Biomedical Applications, through Nano-Scratch Tests and Adhesion Force Maps

Molecules ◽

10.3390/molecules26040900 ◽

2021 ◽

Vol 26 (4) ◽

pp. 900

Author(s):

Maria Vardaki ◽

Aida Pantazi ◽

Ioana Demetrescu ◽

Marius Enachescu

Keyword(s):

Surface Roughness ◽

Functional Properties ◽

Bacterial Adhesion ◽

Biomedical Applications ◽

Adhesion Force ◽

Roughness Parameters ◽

Force Microscopy ◽

Atomic Force ◽

The Mean ◽

Scratch Tests

In this work we present the results of a functional properties assessment via Atomic Force Microscopy (AFM)-based surface morphology, surface roughness, nano-scratch tests and adhesion force maps of TiZr-based nanotubular structures. The nanostructures have been electrochemically prepared in a glycerin + 15 vol.% H2O + 0.2 M NH4F electrolyte. The AFM topography images confirmed the successful preparation of the nanotubular coatings. The Root Mean Square (RMS) and average (Ra) roughness parameters increased after anodizing, while the mean adhesion force value decreased. The prepared nanocoatings exhibited a smaller mean scratch hardness value compared to the un-coated TiZr. However, the mean hardness (H) values of the coatings highlight their potential in having reliable mechanical resistances, which along with the significant increase of the surface roughness parameters, which could help in improving the osseointegration, and also with the important decrease of the mean adhesion force, which could lead to a reduction in bacterial adhesion, are providing the nanostructures with a great potential to be used as a better alternative for Ti implants in dentistry.

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