Motions of an Unstable Retainer in an Instrument Ball Bearing

1994 ◽  
Vol 116 (2) ◽  
pp. 202-208 ◽  
Author(s):  
E. Kingsbury ◽  
R. Walker
Keyword(s):  
Experimental Investigation ◽  
Rigid Body ◽  
Rotation Rate ◽  
High Frequency ◽  
Ball Bearing ◽  
Stable Operation ◽  
Frequency Content ◽  
Outer Race ◽  
Group Rotation ◽  
Inner Race

We made an experimental investigation of the motions of the retainer in an instrument ball bearing during stable operation and during squeal. Radial motions of the retainer were measured with two fiber-light probes mounted 90 physical degrees apart. A signal analyzer was used to determine the phasing and frequency content of the probe signals. During squeal, a high-frequency retainer motion was found to be superimposed on the normal retainer ball group rotation rate. This high-frequency motion, which we call whirl, is a rigid-body translation in a circle. Whirl direction is opposite to the race for outer-race rotation, but in the same direction for inner-race rotation. Whirl frequency is approximately proportional to ball spin rate. The observations agree with predictions made from a squeal model based on retainer-to-ball frictional coupling that was originally presented in 1965.

scholarly journals A Computational Fluid Dynamics Simulation of Oil–Air Flow Between the Cage and Inner Race of an Aero-engine Bearing

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Akinola A. Adeniyi ◽  
Hervé Morvan ◽  
Kathy Simmons
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Ball Bearing ◽  
Flow Behavior ◽  
Dynamics Simulation ◽  
Shaft Speed ◽  
Outer Race ◽  
Fine Mesh ◽  
Entry Points ◽  
Inner Race

In aero-engines, the shafts are supported on bearings that carry the radial and axial loads. A ball bearing is made up of an inner race, an outer race, and a cage, which contains the balls, these together comprise the bearing elements. The bearings require oil for lubrication and cooling. The design of the bearing studied in this work is such that the oil is fed to the bearing through holes/slots in the inner race. At each axial feed location, the oil is fed through a number of equispaced feedholes/slots but there are a different number of holes at each location. Once the oil has passed through the bearing, it sheds outward from both sides into compartments known as the bearing chambers. A number of studies have been carried out on the dynamics of bearings. Most of the analyses consider the contributions of fluid forces as small relative to the interaction of the bearing elements. One of the most sophisticated models for a cage–raceway analysis is based on the work of Ashmore et al. (2003, “Hydrodynamic Support and Dynamic Response for an Inner-Piloted Bearing Cage,” Proc. Inst. Mech. Eng. Part G, 217, pp. 19–28], where the cage–raceway is considered to be a short journal bearing divided into sectors by the oil feeds. It is further assumed that the oil exits from the holes and forms a continuous block of oil that exits outward on both sides of the cage–raceway. In the model, the Reynolds equation is used to estimate the oil dynamics. Of interest in this current work is the behavior of the oil and air within the space bounded by the cage and inner race. The aim is to determine whether oil feed to the bearing can be modeled as coming from a continuous slot or if the discrete entry points must be modeled. A volume of fluid (VOF) computational fluid dynamics (CFD) approach is applied. A sector of a ball bearing is modeled with a fine mesh, and the detailed simulations show the flow behavior for different oil splits to the three feed locations of the bearing, thus providing information useful to understanding oil shedding into the bearing chambers. This work shows that different flow behaviors are predicted by models where the oil inlets through a continuous slot are compared to discrete entry holes. The form and speed of oil shedding from the bearing are found to depend strongly on shaft speed with the shedding speed being slightly higher than the cage linear speed. The break-up pattern of oil on the cage inner surface suggests that smaller droplets will be shed at higher shaft speed.

Investigation of Dynamic Processes in Ball Bearings with Defects

2013 ◽  
Vol 198 ◽  
pp. 651-656 ◽  
Author(s):  
Marijonas Bogdevičius ◽  
Viktor Skrickij
Keyword(s):  
Mathematical Model ◽  
Ball Bearing ◽  
Dynamic Processes ◽  
Experimental Investigations ◽  
Ball Bearings ◽  
Outer Race ◽  
Rolling Element ◽  
Inner Race

The paper considers the dynamics of ball bearings with defects. A mathematical model of a ball bearing with defects is offered. The performed theoretical and experimental investigations of ball bearings with defects are described. Five cases of various defects are investigated, including the defective outer race, the defective inner race, the defective rolling element, the defective inner and outer races, the rolling element and a separator, the worn-out ball bearing.

Analysis of Ball Bearing Vibrations Caused by Outer Race Waviness

1998 ◽  
Vol 120 (4) ◽  
pp. 901-908 ◽  
Author(s):  
K. Ono ◽  
Y. Okada
Keyword(s):  
Experimental Investigation ◽  
Analytical Study ◽  
Ball Bearing ◽  
Analytical Investigation ◽  
Outer Race ◽  
Number Of Factors ◽  
Rolling Elements ◽  
Race Track ◽  
Bearing Vibration ◽  
Radial Gap

An analytical investigation of the shaft vibration caused by a ball bearing is presented in this paper. Bearing vibration could be caused by a number of factors, such as defects occurring on the race track or the rolling elements. A common problem with defective bearings is the generation of waviness on the outer race track during the manufacturing process. The vibration of an automobile drive shaft caused by rolling elements rolling over the waviness surface is transmitted to the passenger cabin, and produces undesirable noise. In this paper an analytical study is undertaken to evaluate the effect of waviness number, radial gap and shaft imbalance on the bearing vibration. An experimental investigation was carried out to confirm the analytical study. The results show that the analytical study and experimental investigation agree very well.

Numerical investigation of the oil–air distribution inside ball bearings with under-race lubrication

2021 ◽  
pp. 135065012110105
Author(s):  
Le Jiang ◽  
Yaguo Lyu ◽  
Wenjun Gao ◽  
Pengfei Zhu ◽  
Zhenxia Liu
Keyword(s):  
High Speed ◽  
Ball Bearing ◽  
Volume Fraction ◽  
Volume Flow Rate ◽  
Ball Bearings ◽  
Outer Race ◽  
Rotating Speed ◽  
Oil Distribution ◽  
Hole Configuration ◽  
Inner Race

Oil distribution inside the under-race lubricated bearing is crucial for lubrication and cooling of high-speed ball bearings. An under-race lubricated ball bearing is modeled to numerically investigate the effects of operating parameters and feed hole configuration on the distribution behavior of lubricant oil. The results of the numerical simulation indicate that the average oil volume fraction changes with a convex trend as the outer race rotating speed increases, while it changes monotonically with the inner race rotating speed, oil volume flow rate, and oil temperature. The extent of oil spreading on the outer race, cage, ball, and inner race decreases successively. Optimizing the feed hole configuration according to the average oil volume fraction is helpful to achieve precise lubrication of the under-race lubricated ball bearing.

Oil-Air Flow Between the Cage and Inner Race of an Aeroengine Bearing

2016 ◽  
Author(s):  
Akinola A. Adeniyi ◽  
Hervé Morvan ◽  
Kathy Simmons
Keyword(s):  
Ball Bearing ◽  
Flow Behaviour ◽  
Shaft Speed ◽  
Axial Loads ◽  
Outer Race ◽  
Fluid Forces ◽  
Fine Mesh ◽  
Entry Points ◽  
Continuous Block ◽  
Inner Race

In aeroengines the shafts are supported on bearings that carry the radial and axial loads. A ball bearing is made up of an inner-race, an outer-race and a cage which contains the balls, these together comprise the bearing elements. The bearings require oil for lubrication and cooling. The design of the bearing studied in this work is such that the oil is fed to the bearing through holes/slots in the inner race. At each axial feed location the oil is fed through a number of equispaced feedholes/slots but there is a different number of holes at each location. Once the oil has passed through the bearing it sheds outwards from both sides into compartments known as the bearing chambers. A number of studies have been carried out on the dynamics of bearings. Most of the analyses consider the contributions of fluid forces as small relative to the interaction of the bearing elements. One of the most sophisticated models for a cage-raceway analysis is based on the work of Ashmore et al. [1], where the cage-raceway is considered to be a short journal bearing divided into sectors by the oil feeds. It is further assumed that the oil exits from the holes and forms a continuous block of oil that exits outwards on both sides of the cage-raceway. In the model, the Reynolds equation is used to estimate the oil dynamics. Of interest in this current work is the behaviour of the oil and air within the space bounded by the cage and inner race. The aim is to determine whether oil feed to the bearing can be modelled as coming from a continuous slot or if the discrete entry points must be modelled. A Volume of Fluid Computational Fluid Dynamics approach is applied. A sector of a ball bearing is modelled with a fine mesh and the detailed simulations show the flow behaviour for different oil splits to the three feed locations of the bearing thus providing information useful to understanding oil shedding into the bearing chambers. The work shows that different flow behaviour is predicted by models where the oil inlets through a continuous slot compared to discrete entry holes. The form and speed of oil shedding from the bearing is found to depend strongly on shaft speed with the shedding speed being slightly higher than the cage linear speed. The break-up pattern of oil on the cage inner surface suggests smaller droplets will be shed at higher shaft speed.

Analysis of Ball Bearing Vibrations Caused by Outer Race Waviness

1997 ◽  
Author(s):  
Koichiro Ono ◽  
Yohji Okada
Keyword(s):  
Experimental Investigation ◽  
Analytical Study ◽  
Ball Bearing ◽  
Vibration Spectrum ◽  
Outer Race ◽  
Rolling Elements ◽  
Race Track ◽  
Efficient Machine ◽  
Radial Gap ◽  
Passenger Cabin

Abstract Even with the use of highly efficient machine, the manufacturing of rolling elements bearings still results in defective bearings. The defects could be on the race track or the rolling elements. A common problem with defective bearing is the generating waviness on the outer race track during the manufacturing process. The vibrations caused by rolling elements rolling over the waviness surface is transmitted to the passenger cabin and produced unwanted noise. In this paper an analytical study was first undertaken to evaluate the effect of waviness number, radial gap and shaft unbalance on the vibration spectrum. Experimental investigation was carried out to confirm the analytical study. The experimental results agreed very well with the numerical analysis.

scholarly journals Effect of Various Defects in Roller Bearings and Ball Bearings on Vibration

2019 ◽  
Vol 8 (12) ◽  
pp. 5137-5141
Keyword(s):  
Ball Bearing ◽  
Surface Defects ◽  
Roller Bearing ◽  
Vibration Response ◽  
Maintenance Cost ◽  
Artificial Defect ◽  
Outer Race ◽  
Vibration Signature ◽  
Inner Race ◽  
Load Conditions

The bearing is very important segment in any rotating machinery. It is continually running under changing speed and load conditions. Failure of bearing frequently results in extensive mechanical downtime that has monetary outcomes. Timely diagnosis of bearing breakdown is to avoid machines failure, as well as to decrease the maintenance cost of machine. To analyze failure of the bearing artificial defect were created on various elements of the bearing and using vibration signature for monitoring its condition analysis is carried.In this paper the effect of various surface defects on the vibration response of outer race and inner race of the ball bearing and Roller bearing is discussed. Vibration spectrum produced by bearing with defect on inner or outer race under different load conditions is taken and effect of defect size and load on the vibration response has been investigated. Results are presented in time and frequency domain. The results obtained by experimentations are compared with MATLAB results

Experimental Investigation of very High Frequency Slot Antenna on M-60A-1 Tank

1977 ◽  
Author(s):  
D. V. Campbell ◽  
William Kennebeck ◽  
A. Zanella ◽  
Paul Sexton
Keyword(s):  
Experimental Investigation ◽  
High Frequency ◽  
Slot Antenna ◽  
Very High Frequency ◽  
Very High

Comparison of wavelet continuous transform and signal averaged ECG for high frequency content and late potential detection in healthy individuals

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
D Garcia Iglesias ◽  
J.M Rubin Lopez ◽  
D Perez Diez ◽  
C Moris De La Tassa ◽  
F.J De Cos Juez ◽  
...  
Keyword(s):  
High Frequency ◽  
Classical Method ◽  
Total Power ◽  
Frequency Content ◽  
Healthy Individuals ◽  
Time Frequency ◽  
Qt Intervals ◽  
Long Time ◽  
Power Content ◽  
High Frequency Content

Abstract Introduction The Signal Averaged ECG (SAECG) is a classical method forSudden Cardiac Death (SCD) risk assessment, by means of Late Potentials (LP) in the filtered QRS (fQRS)[1]. But it is highly dependent on noise and require long time records, which make it tedious to use. Wavelet Continuous Transform (WCT) meanwhile is easier to use, and may let us to measure the High Frequency Content (HFC) of the QRS and QT intervals, which also correlates with the risk of SCD [2,3]. Whether the HFC of the QRS and QT measured with the WCT is a possible subrogate of LP, has never been demonstrated. Objective To demonstrate if there is any relationship between the HFC measured with the WCT and the LP analyzed with the SAECG. Methods Data from 50 consecutive healthy individuals. The standard ECG was digitally collected for 3 consecutive minutes. For the WCT Analysis 8 consecutive QT complexes were used and for the SAECG Analysis all available QRS were used. The time-frequency data of each QT complex were collected using the WCT as previously described [3] and the Total, QRS and QT power were obtained from each patient. For the SAECG, bipolar X, Y and Z leads were used with a bidirectional filter at 40 to 250 Hz [1]. LP were defined as less than 0.05 z in the terminal part of the filtered QRS and the duration (SAECG LP duration) and root mean square (SAECG LP Content) of this LP were calculated. Pearson's test was used to correlate the Power content with WCT analysis and the LP in the SAECG. Results There is a strong correlation between Total Power and the SAECG LP content (r=0.621, p<0.001). Both ST Power (r=0.567, p<0.001) and QRS Power (r=0.404, p=0.004) are related with the SAECG LP content. No correlation were found between the Power content (Total, QRS or ST Power) and the SAECG LP duration. Also no correlation was found between de SAECG LP content and duration. Conclusions Total, QRS and ST Power measured with the WCT are good surrogates of SAECG LP content. No correlation were found between WCT analysis and the SAECG LP duration. Also no correlation was found between the SAECG LP content and duration. This can be of high interest, since WCT is an easier technique, not needing long recordings and being less affected by noise. Funding Acknowledgement Type of funding source: None

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