Fretting Corrosion Caused by Vibration With Rolling Bearings Stationary

1965 ◽  
Vol 87 (3) ◽  
pp. 713-723 ◽  
Author(s):  
Hans Pittroff
Keyword(s):  
Elastic Deformation ◽  
Contact Area ◽  
Static Load ◽  
Bearing Failure ◽  
Fretting Corrosion ◽  
Rolling Bearings ◽  
Rolling Elements ◽  
Shearing Strength ◽  
Extent Of Damage ◽  
Short Time

If nonrotating rolling bearings are exposed to vibration then the raceways especially in roller bearings can be damaged in a short time. False brinelling in bearings is caused by fretting corrosion. All research in this area therefore belongs to the field of fretting corrosion. Owing to the alternating elastic deformation in the contact area between the rolling elements and the raceway as well as to the shearing strength being exceeded in the microcontact area, surface particles are abraded, which become immediately oxidized. The kind and the extent of damage primarily depend on the static load of the bearings. The resistance to false brinelling can be increased by means of lubricants and surface treatments. It is possible to give limits for the admissible flute characteristics. In cases of already known vibration characteristics the time of the bearing failure can be mathematically predetermined.

Electric impedance of rolling bearings - Consideration of unloaded rolling elements

2021 ◽  
Vol 158 ◽  
pp. 106927
Author(s):  
T. Schirra ◽  
G. Martin ◽  
S. Puchtler ◽  
E. Kirchner
Keyword(s):  
Electric Impedance ◽  
Rolling Bearings ◽  
Rolling Elements

scholarly journals STUDY OF EFFECT OF SOLID CONTAMINANTS IN THE LUBRICANT ON BALL BEARINGS VIBRATION

2012 ◽  
pp. 28-31
Author(s):  
ONKAR L. MAHAJAN ◽  
ABHAY A. UTPAT
Keyword(s):  
Experimental Tests ◽  
Solid Particles ◽  
Particle Sizes ◽  
Ball Bearings ◽  
Bearing Failure ◽  
Mean Square ◽  
Rolling Bearings ◽  
Vibration Signals ◽  
Deep Groove ◽  
Concentration Levels

In deep groove ball bearings contamination of lubricant grease by solid particles is one of the main reason for early bearing failure. To deal with such problem, it is fundamental not only the use of reliable techniques concerning detection of solid contamination but also the investigation of the effects of certain contaminant characteristics on bearing performance. Nowadays the techniques such as vibration measurements are being increasingly used for on-time monitoring of machinery performance. The present work investigates the effect of lubricant contamination by solid particles on the dynamic behavior of rolling bearings, in order to determine the trends in the amounts of vibration affected by contamination in the Grease and by the bearing wear itself. Experimental tests are performed with Deep-groove ball bearings. The Dolomite powder in three concentration levels and different particle sizes was used to contaminate the grease. Vibration signals were analyzed in terms of Root Mean Square (RMS) values and also in terms of defect frequencies.

A Coupled Approach for Modelling Rolling Contact Fatigue Cracks Under Elastohydrodynamic Lubrication

2009 ◽  
Author(s):  
R. Balcombe ◽  
M. T. Fowell ◽  
A. V. Olver ◽  
D. Dini
Keyword(s):  
Fluid Flow ◽  
Elastic Deformation ◽  
Contact Area ◽  
Fatigue Cracks ◽  
Moving Load ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Elastohydrodynamic Lubrication ◽  
Rolling Contact ◽  
Fluid Solid Interaction

In this paper we present a coupled method for modelling fluid-solid interaction within a crack generated in rolling contact fatigue (RCF) in the presence of lubrication. The technique describes the fluid flow in the contact area and within the crack and explores how this affects the elastic deformation of the solid while the moving load traverses the cracked region. It is argued that this approach sheds light on the instantaneous response of the system, therefore providing a more physically-accurate description of the phenomenon under investigation.

Diagnosis of Rolling-Element Bearings Failure by Localized Electrical Current Between Track Surfaces of Races and Rolling-Elements

2002 ◽  
Vol 124 (3) ◽  
pp. 468-473 ◽  
Author(s):  
Har Prashad
Keyword(s):  
Theoretical Model ◽  
Electrical Current ◽  
Rolling Element Bearing ◽  
Rolling Element Bearings ◽  
Bearing Failure ◽  
Cause Analysis ◽  
Rolling Element ◽  
Rolling Elements ◽  
Dimensional Parameters ◽  
Element Bearing

The diagnosis and cause analysis of rolling-element bearing failure have been well studied and established in literature. Failure of bearings due to unforeseen causes were reported as: puncturing of bearings insulation; grease deterioration; grease pipe contacting the motor base frame; unshielded instrumentation cable; the bearing operating under the influence of magnetic flux, etc. These causes lead to the passage of electric current through the bearings of motors and alternators and deteriorate them in due course. But, bearing failure due to localized electrical current between track surfaces of races and rolling-elements has not been hitherto diagnosed and analyzed. This paper reports the cause of generation of localized current in presence of shaft voltage. Also, it brings out the developed theoretical model to determine the value of localized current density depending on dimensional parameters, shaft voltage, contact resistance, frequency of rotation of shaft and rolling-elements of a bearing. Furthermore, failure caused by flow of localized current has been experimentally investigated.

Material Considerations for High Temperature Tilting Pad Gas Bearings

1968 ◽  
Vol 90 (4) ◽  
pp. 818-828 ◽  
Author(s):  
S. F. Murray ◽  
M. B. Peterson
Keyword(s):  
High Temperature ◽  
Contact Area ◽  
High Speed ◽  
Contact Problems ◽  
Sliding Contact ◽  
Gas Bearings ◽  
Hydrodynamic Bearing ◽  
Tilting Pad ◽  
Short Time

This paper is concerned with the sliding contact problems encountered in tilting pad gas bearings operating at temperatures up to 1400 deg F. Both the pivots and the bearing surfaces are considered. Short time experimental evaluations of pivot damage are summarized. The results of start-stop and high-speed rub tests on a single tilting pad hydrodynamic bearing are also described. Based on the results obtained to date, damage-resistant coatings are available for use on the bearing surfaces at high temperature. There are also suitable pivot materials, but the pivot must be properly designed to minimize slip in the contact area.

A Method to Determine the Static Load Distribution in a Chain Drive

1999 ◽  
Vol 121 (3) ◽  
pp. 402-408 ◽  
Author(s):  
I. Troedsson ◽  
L. Vedmar
Keyword(s):  
Elastic Deformation ◽  
Load Distribution ◽  
Gravitational Force ◽  
Static Load ◽  
Chain Drive ◽  
Standard Geometry ◽  
A Chain ◽  
Force Equilibrium

A model of how to calculate the load distribution for a chain drive is presented. In the model the complete standard geometry is used without any assumptions. The rollers which are in contact with the sprockets can move freely along the tooth flanks and their positions are given by force equilibrium. Since the positions of the rollers and thereby also the load distribution are dependent on the two connecting spans, these necessary tight and slack spans have been included in the model. The elastic deformation in the chain is included as well as the gravitational force.

Standard Uncertainty of Rolling Bearing Vibration as Time Series

2011 ◽  
Vol 382 ◽  
pp. 133-136
Author(s):  
Xin Tao Xia ◽  
Lei Lei Gao ◽  
Xiao Chao Sun
Keyword(s):  
Time Series ◽  
Measurement Theory ◽  
Failure Process ◽  
Rolling Bearing ◽  
Standard Uncertainty ◽  
Bearing Failure ◽  
Vibration Acceleration ◽  
Rolling Bearings ◽  
Vibrational Acceleration ◽  
Bearing Vibration

The standard uncertainty in the measurement theory is applied to evaluate the change of the rolling bearing vibration acceleration generated by the failure on the surface of the ring raceway. The time series are obtained via the experimental investigation on the vibrational acceleration of the rolling bearings with different failure diameters. And the result shows that the standard uncertainty of the vibrational acceleration increases nonlinearly with the failure diameter, revealing a new characteristic of the variation of the rolling bearing failure process. It follows that for a rolling bearing in running, the failure process can be described by the standard uncertainty of its vibration acceleration, laying a foundation for failure warning of a rolling bearing.

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