Simultaneous Monitoring of Rolling-Element and Journal Bearings Using Analysis of Structure-Born Ultrasound Acoustic Emissions

2010 ◽  
Author(s):  
A. Albers ◽  
M. Dickerhof
Keyword(s):  
Acoustic Emission ◽  
Acoustic Emissions ◽  
Piezoelectric Sensor ◽  
Journal Bearings ◽  
Rolling Element Bearings ◽  
Acoustic Emission Sensor ◽  
Outer Race ◽  
Rolling Element ◽  
Characteristic Values ◽  
Acoustic Emission Technology

The application of Acoustic Emission technology for monitoring rolling element or hydrodynamic plain bearings has been addressed by several authors in former times. Most of these investigations took place under idealized conditions, to allow the concentration on one single source of emission, typically recorded by means of a piezoelectric sensor. This can be achieved by either eliminating other sources in advance or taking measures to shield them out (e. g. by placing the acoustic emission sensor very close to the source of interest), so that in consequence only one source of structure-born sound is present in the signal. With a practical orientation this is often not possible. In point of fact, a multitude of potential sources of emission can be worth considering, unfortunately superimposing one another. The investigations reported in this paper are therefore focused on the simultaneous monitoring of both bearing types mentioned above. Only one piezoelectric acoustic emission sensor is utilized, which is placed rather far away from the monitored bearings. By derivation of characteristic values from the sensor signal, different simulated defects can be detected reliably: seeded defects in the inner and outer race of rolling element bearings as well as the occurrence of mixed friction in the sliding surface bearing due to interrupted lubricant inflow.

Experimental investigation on time-domain features in the diagnosis of rolling element bearings by acoustic emission

2021 ◽  
pp. 107754632110161
Author(s):  
Aref Aasi ◽  
Ramtin Tabatabaei ◽  
Erfan Aasi ◽  
Seyed Mohammad Jafari
Keyword(s):  
Acoustic Emission ◽  
Condition Monitoring ◽  
Time Domain ◽  
Central Moment ◽  
Rolling Element Bearings ◽  
Test Rig ◽  
Acoustic Emission Sensor ◽  
Outer Race ◽  
Common Time ◽  
Rolling Element

Inspired by previous achievements, different time-domain features for diagnosis of rolling element bearings are investigated in this study. An experimental test rig is prepared for condition monitoring of angular contact bearing by using an acoustic emission sensor for this purpose. The acoustic emission signals are acquired from defective bearing, and the sensor takes signals from defects on the inner or outer race of the bearing. By studying the literature works, different domains of features are classified, and the most common time-domain features are selected for condition monitoring. The considered features are calculated for obtained signals with different loadings, speeds, and sizes of defects on the inner and outer race of the bearing. Our results indicate that the clearance, sixth central moment, impulse, kurtosis, and crest factors are appropriate features for diagnosis purposes. Moreover, our results show that the clearance factor for small defects and sixth central moment for large defects are promising for defect diagnosis on rolling element bearings.

Spalling Size Evaluation of Rolling Element Bearing Using Acoustic Emission

2013 ◽  
Vol 569-570 ◽  
pp. 497-504 ◽  
Author(s):  
An Bo Ming ◽  
Zhao Ye Qin ◽  
Wei Zhang ◽  
Fu Lei Chu
Keyword(s):  
Acoustic Emission ◽  
Rolling Element Bearing ◽  
Rolling Element Bearings ◽  
Outer Race ◽  
Cepstrum Analysis ◽  
Rolling Element ◽  
Rolling Elements ◽  
Element Bearing ◽  
Envelope Spectrum ◽  
Size Evaluation

Spalling of the races or rolling elements is one of the most common faults in rolling element bearings. Exact estimation of the spall size is helpful to the life prediction for rolling element bearings. In this paper, the dual-impulsive phenomenon in the response of a spalled rolling element bearing is investigated experimentally, where the acoustic emission signals are utilized. A new method is proposed to estimate the spall size by extracting the envelope of harmonics of the ball passing frequency on the outer race from the squared envelope spectrum. Compared with the cepstrum analysis, the proposed procedure shows more powerful anti-noise ability in the fault size evaluation.

Some Effects of Lubricant Composition and Tappet Rotation on Cam/Tappet Friction

1989 ◽  
Vol 111 (4) ◽  
pp. 683-691 ◽  
Author(s):  
P. A. Willermet ◽  
J. Pieprzak
Keyword(s):  
Experimental Data ◽  
Frictional Contact ◽  
Angular Resolution ◽  
Friction Model ◽  
Journal Bearings ◽  
Valve Train ◽  
Wave Form ◽  
Rolling Element Bearings ◽  
Lubricant Composition ◽  
Rolling Element

A cam/tappet friction rig was constructed from a 1.6 L Ford valve train. The head casting and the camshaft were shortened so that only two journal bearings remained. Only one of the two remaining cam/tappet contacts was used as a frictional contact. All other contacts were equipped with rolling element bearings so that essentially all the turning torque came from cam/tappet friction and valve spring forces. The rig, together with a data acquisition/wave form analyzer system and a computer, was capable of measuring instantaneous torque with an angular resolution of less than one degree, and reducing the data to provide calculated values for parameters such as the friction coefficient. The experimental data were compared with results from a cam/tappet friction model to assist in interpretation. The data and model illustrated that lubricant composition and tappet rotation have important effects not only on overall friction, but also on the shape of friction versus cam angle curves.

Feature Selection for Fault Detection in Rolling Element Bearings Using Mutual Information

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Karthik Kappaganthu ◽  
C. Nataraj
Keyword(s):  
Fault Detection ◽  
Mutual Information ◽  
Quantitative Measure ◽  
Rolling Element Bearings ◽  
Outer Race ◽  
Time Frequency ◽  
Rolling Element ◽  
Degree Of Confidence ◽  
Hidden Layer ◽  
Optimal Feature

Rolling element bearings are among the key components in many rotating machineries. It is hence necessary to determine the condition of the bearing with a reasonable degree of confidence. Many techniques have been developed for bearing fault detection. Each of these techniques has its own strengths and weaknesses. In this paper, various features are compared for detecting inner and outer race defects in rolling element bearings. Mutual information between the feature and the defect is used as a quantitative measure of quality. Various time, frequency, and time-frequency domain features are compared and ranked according to their cumulative mutual information content, and an optimal feature set is determined for bearing classification. The performance of this optimal feature set is evaluated using an artificial neural network with one hidden layer. An overall classification accuracy of 97% was obtained over a range of rotating speeds.

Simulations and Measurements of the Vibroacoustic Effects of Replacing Rolling Element Bearings With Journal Bearings in a Simple Gearbox

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Stephen A. Hambric ◽  
Micah R. Shepherd ◽  
Robert L. Campbell ◽  
Amanda D. Hanford
Keyword(s):  
Finite Element Analysis ◽  
Journal Bearings ◽  
Component Mode Synthesis ◽  
Rolling Element Bearings ◽  
Element Analysis ◽  
Free Boundary Conditions ◽  
Damping Coefficients ◽  
Rolling Element ◽  
Gearbox Vibration ◽  
Solution Methods

The effects of replacing rolling element bearings with journal bearings on the noise and vibration of a simple gearbox are computationally and experimentally evaluated. A modified component mode synthesis (CMS) approach is used, where the component modes of the shafting and gearbox housing are modeled using finite element analysis (FEA). Instead of using component modes with free boundary conditions, which is typical of CMS, the shafting and gearbox are coupled using nominal impedances computed for the different bearing types, improving convergence of the solution. Methods for computing the actual bearing impedances, including the high damping coefficients in journal bearings, are summarized. The sound radiated by the gearbox is computed using a boundary element (BE) model. The modeling results are validated against measurements made at the NASA Glenn Research Center. Both simulations and measurements reveal that the journal bearings, although highly damped, do not necessarily lead to strong reductions in gearbox vibration and noise.

Detection of Incipient Damage in Large Rolling Element Bearings

2006 ◽  
Vol 13-14 ◽  
pp. 37-44 ◽  
Author(s):  
Leonard M. Rogers
Keyword(s):  
Acoustic Emission ◽  
The Body ◽  
Metal Loss ◽  
Rolling Element Bearings ◽  
Variable Speed ◽  
Fluid Turbulence ◽  
Rolling Element ◽  
Acoustic Emission Source ◽  
Reliable Detection ◽  
True Condition

The paper describes a methodology for the reliable detection of incipient damage due to fatigue, fretting and false brinelling in large, heavily loaded rolling element bearings such as found in pedestal slewing cranes and ship azi-pod propulsors. It has been found that combining acoustic emission source location and spectrum analysis of the associated time-domain signatures has produced a powerful diagnostic tool for the detection of micro-damage to the various working faces of the bearing under variable speed and loading conditions, before any metal loss is evident in the bearing lubricant. Other sources of acoustic emission such as fretting at contact faces elsewhere in the body of the bearing and fluid turbulence can be resolved and quantified so as not to interfere with the diagnosis of bearing condition. Results are presented for new and damaged bearings, where the true condition has been verified when the bearings were subsequently replaced.

Detecting Shaft-to-Seal Rubbing in Power Generation Turbines With the Acoustic Emission Technology

2006 ◽  
Vol 128 (6) ◽  
pp. 798-800 ◽  
Author(s):  
M. Leahy ◽  
D. Mba ◽  
P. Cooper ◽  
A. Montgomery ◽  
D. Owen
Keyword(s):  
Power Generation ◽  
Acoustic Emission ◽  
Journal Bearings ◽  
Experimental Program ◽  
Acoustic Emission Technology

This paper presents results of an investigation to assess the potential of the acoustic emission (AE) technology for detecting seal-to-rotor rubbing in power generation turbines. The experimental program involved inducing rubs at various axial locations along a 412ton test rotor, rotating at 3000rpm and supported by 7in.(178mm) journal bearings. Whilst there was no change in vibration levels throughout the tests, bearing mounted AE transducers successfully detected all rubbing induced on the rotor.

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