Analysis of a Rolling-Element Idler Gear Bearing Having a Deformable Outer-Race Structure

1963 ◽  
Vol 85 (2) ◽  
pp. 273-278 ◽  
Author(s):  
A. B. Jones ◽  
T. A. Harris
Keyword(s):  
Fatigue Life ◽  
High Speed ◽  
Roller Bearing ◽  
Rolling Element Bearing ◽  
Outer Ring ◽  
Outer Race ◽  
Rolling Element ◽  
Rolling Elements ◽  
Planet Gear ◽  
Bearing Rings

Conventional calculations of ball and roller bearing carrying capacity and fatigue life assume that the raceway bodies are rigid structures and that all elastic deformation occurs at the rolling elements’ contact with the raceways. In many instances, and particularly with aircraft applications, the bearing rings and their supports cannot be considered rigid. One such application is the planet gear in a transmission. This report develops a theory whereby the effects of the elastic distortions of the outer race of a rolling-element bearing on the internal load distribution and fatigue life of the bearing can be considered. The theory has been programmed for a high-speed, digital computer. An example of calculation for a planet gear roller bearing whose outer race is integral with the gear and of relatively thin section is given. The distortions of the flexible outer ring cause a significantly lower bearing fatigue life (L10) than would occur if the outer ring were rigid and considering a practical range of bearing diametral clearances. Mr. Jones developed the theoretical analysis for this paper and Mr. Harris provided the programming and the experimental data.

scholarly journals Fatigue Life of High-Speed Ball Bearings With Silicon Nitride Balls

1975 ◽  
Vol 97 (3) ◽  
pp. 350-355 ◽  
Author(s):  
R. J. Parker ◽  
E. V. Zaretsky
Keyword(s):  
Fatigue Life ◽  
Silicon Nitride ◽  
High Speed ◽  
Bearing Steel ◽  
Rolling Element Bearing ◽  
Ball Bearings ◽  
Rolling Element ◽  
Low Mass ◽  
Element Bearing ◽  
Steel Balls

Hot-pressed silicon nitride was evaluated as a rolling-element bearing material. This material has a low specific gravity (41 percent that of bearing steel) and has a potential application as low mass balls for very high-speed ball bearings. The five-ball fatigue tester was used to test 12.7-mm- (0.500-in-) dia silicon nitride balls at maximum Hertz stresses ranging from 4.27 × 109 N/m2 (620,000 psi) to 6.21 × 109 N/m2 (900,000 psi) at a race temperature of 328K (130 deg F). The fatigue life of NC-132 hot-pressed silicon nitride was found to be equal to typical bearing steels and much greater than other ceramic or cermet materials at the same stress levels. A digital computer program was used to predict the fatigue life of 120-mm- bore angular-contact ball bearings containing either steel or silicon nitride balls. The analysis indicates that there is no improvement in the lives of bearings of the same geometry operating at DN values from 2 to 4 million where silicon nitride balls are used in place of steel balls.

Analysis of an Improved Planetary Gear-Transmission Bearing

1964 ◽  
Vol 86 (3) ◽  
pp. 457-461 ◽  
Author(s):  
T. A. Harris ◽  
J. L. Broschard
Keyword(s):  
Fatigue Life ◽  
Gear Tooth ◽  
Roller Bearing ◽  
Planetary Gear ◽  
Major Axis ◽  
Rolling Bearing ◽  
Load Application ◽  
Outer Ring ◽  
Rolling Element ◽  
Oriented Parallel

In planetary-gear transmissions, especially for aircraft applications, the planet gears are frequently made integral with the outer rings of rolling bearings. Thus the outer ring of the rolling bearing is subjected to the tangential, radial, and moment loading attendant to spur gears. If the outer ring of the bearing is relatively thin, the distortion induced therein by the gear forces alters the distribution of load from that of a roller bearing with a rigid outer ring, causing a significant reduction in the bearing fatigue life. Since the maximum rolling-element loads in the bearing occur in close angular proximity of the points of load application, it would appear that the magnitude of these rolling-element loads may be diminished and fatigue life subsequently increased by selectively applying clearance between rolling elements and raceway at the points of load application. In fact, theoretical analysis of a planetary-gear bearing having an out-of-round inner ring, wherein the major axis is oriented parallel to the tangential gear-tooth load, indicates that a condition of optimum clearance and out-of-round exists with respect to bearing fatigue life. An increase in fatigue life of approximately 40 percent is indicated with only a nominal amount of out-of-round.

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.

scholarly journals The Series Hybrid Bearing—A New High Speed Bearing Concept

1972 ◽  
Vol 94 (2) ◽  
pp. 117-122 ◽  
Author(s):  
W. J. Anderson ◽  
D. P. Fleming ◽  
R. J. Parker
Keyword(s):  
Fatigue Life ◽  
High Speed ◽  
Ball Bearing ◽  
Rolling Element Bearing ◽  
Speed Ratio ◽  
Shaft Speed ◽  
Rolling Element ◽  
Element Bearing ◽  
Hybrid Bearing ◽  
Inner Race

The series-hybrid bearing couples a fluid-film bearing with a rolling-element bearing such that the rolling-element bearing inner race runs at a fraction of shaft speed. A series-hybrid bearing was analyzed and experiments were run at thrust loads from 100 to 300 lb and speeds from 4000 to 30,000 rpm. Agreement between theoretical and experimental speed sharing was good. The lowest speed ratio (ratio of ball bearing inner-race speed to shaft speed) obtained was 0.67. This corresponds to an approximate reduction in DN value of 1/3. For a ball bearing in a 3 million DN application, fatigue life would theoretically be improved by a factor as great as 8.

scholarly journals Transient Vibration Prediction for Rotors on Ball Bearings Using Load-Dependent Nonlinear Bearing Stiffness

2004 ◽  
Vol 10 (6) ◽  
pp. 489-494 ◽  
Author(s):  
David P. Fleming ◽  
J. V. Poplawski
Keyword(s):  
High Speed ◽  
Roller Bearing ◽  
Transient Behavior ◽  
Rolling Element Bearing ◽  
Ball Bearings ◽  
Transient Vibration ◽  
Vibration Prediction ◽  
Rolling Element ◽  
Bearing Stiffness ◽  
Element Bearing

Rolling-element bearing forces vary nonlinearly with bearing deflection. Thus an accurate rotordynamic transient analysis requires bearing forces to be determined at each step of the transient solution. Analyses have been carried out to show the effect of accurate bearing transient forces (accounting for nonlinear speed and load-dependent bearing stiffness) as compared to conventional use of average rolling-element bearing stiffness. Bearing forces were calculated by COBRA-AHS (Computer Optimized Ball and Roller Bearing Analysis—Advanced High Speed) and supplied to the rotordynamics code ARDS (Analysis of Rotor Dynamic Systems) for accurate simulation of rotor transient behavior. COBRA-AHS is a fast-running five degree-of-freedom computer code able to calculate high speed rolling-element bearing load-displacement data for radial and angular contact ball bearings and also for cylindrical and tapered roller bearings. Results show that use of nonlinear bearing characteristics is essential for accurate prediction of rotordynamic behavior.

scholarly journals CYLINDRICAL ROLLER BEARING LUBRICATION REGIMES ANALYSIS AT LOW SPEED AND PURE RADIAL LOAD

2019 ◽  
Vol 59 (3) ◽  
pp. 272-282
Author(s):  
Jakub Chmelař ◽  
Karel Petr ◽  
Petr Mikeš ◽  
Vojtěch Dynybyl
Keyword(s):  
Roller Bearing ◽  
Radial Load ◽  
Lubrication Regimes ◽  
Lubrication Film ◽  
Press Fit ◽  
Lubrication Regime ◽  
Rolling Element ◽  
Rolling Elements ◽  
Cylindrical Roller Bearing ◽  
Bearing Rings

In this article, we describe a method of the roller bearing lubrication regime prediction. It uses a mathematical model of the bearing based on the standard ISO/TS 16281 to obtain the external load distribution over the rolling elements. We consider the effects of press fit and thermal gradient etween bearing rings on the internal clearance. The model is limited to an input of an uni-axial radial load and it neglects the centrifugal forces and gyroscopic moments due to its application for the region of low speeds. The lubrication film thickness is evaluated for the most loaded rolling element by a numerical solution of Reynolds’ equation for the line contact. The assessment of the lubrication regime takes into the account the surface roughness by employing the lubrication coefficient as an output parameter. Presented outcomes of the study, based on the measured geometry of the bearing, show the importance of an appropriate lubricant selection for the application.

Rolling Element Bearing Monitoring Using High Gain Eddy Current Transducers

1985 ◽  
Vol 107 (1) ◽  
pp. 160-164 ◽  
Author(s):  
R. G. Harker ◽  
J. S. Hansen
Keyword(s):  
Eddy Current ◽  
High Speed ◽  
High Gain ◽  
Activity Monitor ◽  
Rolling Element Bearing ◽  
Bearing Failure ◽  
Outer Race ◽  
Rolling Element ◽  
Element Bearing ◽  
Bearing Monitoring

A technique is described which provides early detection of rolling element bearing failure through direct observation of the bearing outer race with a high-gain eddy current probe. Data is presented that compares REBAM™—Rolling Element Bearing Activity Monitor—to traditional monitoring approaches that employ case mounted velocity and acceleration transducers. Generally, the REBAM approach simplifies the analysis of bearing condition because of its proximity to the bearing and its insensitivity to extraneous vibration sources due to the relative mounting approach employed. A summary of field results is presented and its suitability to high speed gas turbine monitoring is discussed.

A New Vibration of Rolling Element Bearing With Localized Defect Considering the Impact Force

2015 ◽  
Author(s):  
Wentao Huang ◽  
Zhenzhen Dong ◽  
Fanchao Kong ◽  
Qiang Fu
Keyword(s):  
Impact Force ◽  
Structural Parameters ◽  
Rolling Element Bearing ◽  
Mechanism Analysis ◽  
Outer Race ◽  
Contact Areas ◽  
Deep Groove ◽  
Rolling Element ◽  
Rolling Elements ◽  
The Impact

In this paper, a vibration model considering the impact force is developed based on Hertz contact theory. The model considered both structural parameters and kinematic parameters. In this model, the contact areas between balls and races are simulated as linear springs, and the contact areas between the inner race and shaft and the contact areas between the outer race and housing are considered as spring-damper systems. Unlike previous studies, in which the stiffness was simply calculated in one direction, the stiffness parameters were calculated separately in the horizontal and vertical directions in the present study. In this model, the impact process between rolling elements and defective races, which is affected by velocity, was studied in detail. The solution of the vibration equation was obtained using the Runge-Kutta method. The numerical results for 6204 deep groove type ball bearings with outer race defects have been obtained and compared with the experimental results, which validated the effectiveness of this model in both the fault mechanism analysis of rolling element bearings and fault diagnosis.

An Enhanced Study of the Load–Displacement Relationships for Rolling Element Bearings

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
L. Houpert
Keyword(s):  
Contact Angle ◽  
Roller Bearing ◽  
Rolling Element Bearing ◽  
Smooth Transition ◽  
Ball Bearings ◽  
Element Analysis ◽  
Outer Race ◽  
Deep Groove ◽  
Rolling Element ◽  
Element Bearing

An enhanced analytical approach is suggested for calculating three rolling element bearing loads Fx, Fy, and Fz as well as the two tilting moments My and Mz as a function of five relative race displacements: three translations dx, dy, and dz, and two tilting angles dθy and dθz. A full coupling between all these displacements and forces is considered. This approach is particularly recommended for programming the rolling element bearing behavior in any finite element analysis or multibody system dynamic tool, since only two nodes are considered: one for the inner race center, usually connected to a shaft, and another node for the outer race center, connected to the housing. Also, roller and raceway crown radii are considered, meaning that Hertzian point contacts stiffness can be used at low load with a smooth transition toward Hertzian line contact as the load increases. This approach can be used for describing any rolling element bearing type when neglecting centrifugal and gyroscopic effects and applying the approximation of a constant ball–race contact angle. Deep groove ball bearings (whose contact angle sign follows the sign of the applied bearing axial force) or other ball bearings or spherical roller bearing operating under large misalignment may not support such approximations.

Application of Degree of Cyclostationarity in Rolling Element Bearing Diagnosis

2005 ◽  
Vol 293-294 ◽  
pp. 347-354 ◽  
Author(s):  
Guo Bi ◽  
Jin Chen ◽  
Jun He ◽  
Fuchang Zhou ◽  
Gui Cai Zhang
Keyword(s):  
Frequency Domain ◽  
Rolling Element Bearing ◽  
Rolling Element Bearings ◽  
Spectral Correlation ◽  
Outer Race ◽  
Cyclic Frequency ◽  
Bearing Condition Monitoring ◽  
Rolling Element ◽  
Rolling Elements ◽  
Element Bearing

Minor and random slip between rolling elements and races in rolling element bearings makes vibration signals have periodically time-varying ensemble statistics, which is known as cyclostationarity. Two second-order cyclostationary methods, the spectral correlation density (SCD) and the degree of cyclostationarity (DCS), are talked about in this paper based on a statistical model of rolling element bearings. The SCD provides redundant information in bi-frequency plane and cyclic frequency domain embodies the majority of it, which is a series of non-zero discrete cyclic frequencies completely reflecting the fault characters of rolling element bearings. The DCS has virtues of less computation and clearer representation, at the same time keeps the same characters with SCD in cyclic frequency domain. And the DCS is also proved to be resistant to the additive and multiplicative stationary noise. Simulation and experiential results from three rolling element bearing faults: outer race defect, inner race defect and rolling element defect, indicate practicability of the DCS analysis in rolling element bearing condition monitoring and fault diagnosis.

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