Propagation of Contact Fatigue From Surface and Subsurface Origins

1966 ◽  
Vol 88 (3) ◽  
pp. 624-635 ◽  
Author(s):  
W. E. Littmann ◽  
R. L. Widner
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Fatigue Failure ◽  
Contact Stress ◽  
Environmental Conditions ◽  
Failure Modes ◽  
Contact Fatigue ◽  
Initiation And Propagation ◽  
Tapered Roller ◽  
Tapered Roller Bearings

Fatigue life of tapered roller bearings and other elements subject to cyclic contact stress reflects the fatigue strength of the selected material under given environmental conditions. The various modes of contact-fatigue failure have been classified according to their appearance and the factors which promote their initiation and propagation. Illustrations of the various failure modes include rig test specimens and bearings representing normal catalog-rated life under laboratory and application environments. Evidence is presented for the propagation of contact fatigue from surface and subsurface origins.

Prediction of Equivalent Radial Loads for Tapered Roller Bearings

1996 ◽  
Vol 118 (3) ◽  
pp. 651-656
Author(s):  
Ted E. Bailey ◽  
Robert W. Frayer
Keyword(s):  
Fatigue Life ◽  
Rolling Contact Fatigue ◽  
Roller Bearing ◽  
Contact Fatigue ◽  
Subsequent Development ◽  
Rolling Contact ◽  
Tapered Roller Bearing ◽  
Applied Loading ◽  
Tapered Roller ◽  
Tapered Roller Bearings

Calculating the fatigue life of a tapered roller bearing has become a rather straightforward exercise thanks to the accumulation of rolling contact fatigue data and the subsequent development of formulation relating applied loading to bearing fatigue life. An integral part of the prediction process is to define an equivalent radial load (EQRL) by combining a bearing’s applied radial and thrust loading into a single entity. This paper reviews currently accepted formulation and offers a potentially more accurate alternative method for estimating the EQRL of a tapered roller bearing than does the current AFBMA standard.

An Initial Appraisal of the Contact Fatigue Strength of Electron Beam Melted Bearing Steel

1972 ◽  
Vol 94 (2) ◽  
pp. 174-178 ◽  
Author(s):  
R. L. Widner
Keyword(s):  
Electron Beam ◽  
Fatigue Strength ◽  
Contact Fatigue ◽  
Bearing Steel ◽  
Mineral Oils ◽  
Contact Fatigue Strength ◽  
Bearing Life ◽  
Life Tests ◽  
Tapered Roller ◽  
Tapered Roller Bearings

Three test groups of 2.75 in. bore tapered roller bearings were manufactured from pilot heats of cold hearth electron beam remelted modified 4620 steel, a heat of standard consumable electrode vacuum remelted (CV) 4620 steel and from conventionally melted modified 4620 bearing steel. Bearing life tests were performed in a synthetic fluid and two mineral oils of different viscosity to determine the contact fatigue strength of the electron beam melted steel as compared to the CV steel and conventional steel. The electron beam and the consumable vacuum melted steel had equivalent contact fatigue strength in this initial appraisal. The CV steel had contact fatigue strength 4.5 to 9.8 times better than the conventional bearing steel.

scholarly journals Rolling Wear of Silicon Nitride Bearing Materials

1990 ◽  
Author(s):  
John W. Lucek
Keyword(s):  
Fatigue Life ◽  
Silicon Nitride ◽  
Failure Modes ◽  
Fatigue Testing ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Wear Performance ◽  
Wear Rates ◽  
Bearing Materials

Rolling-contact fatigue test methods were used to measure the wear performance of several silicon nitride materials. Sintered, hot pressed and hot isostatically pressed materials exhibited wear rates ranging over three orders of magnitude. Hot isostatically pressed materials had the lowest wear rates. Despite the disparity in wear performance, all materials tested had useful rolling-contact fatigue lives compared to steel. Fatigue life estimates, failure modes, and rolling wear performance for theses ceramics are compared to M-50 steel. This work highlights the rapid contact stress reductions that occur due to conformal wear in rolling-contact fatigue testing. Candidate bearing materials with unacceptably high wear rates may exhibit useful fatigue lives. Rolling contact bearing materials must possess useful wear and fatigue resistance. Proper performance screening of candidate bearing materials must describe the failure mode, wear rate, and the fatigue life. Guidelines for fatigue testing methods are proposed.

scholarly journals Comparison of planetary bearing load-sharing characteristics in wind turbine gearboxes

2018 ◽  
Vol 3 (2) ◽  
pp. 947-960 ◽  
Author(s):  
Jonathan Keller ◽  
Yi Guo ◽  
Zhiwei Zhang ◽  
Doug Lucas
Keyword(s):  
Fatigue Life ◽  
Wind Turbine ◽  
Load Sharing ◽  
Position Error ◽  
Bearing Clearance ◽  
Roller Bearings ◽  
Bearing Load ◽  
Tapered Roller ◽  
Tapered Roller Bearings ◽  
Cylindrical Roller

Abstract. In this paper, the planetary load-sharing behavior and fatigue life of different wind turbine gearboxes when subjected to rotor moments are examined. Two planetary bearing designs are compared – one design using cylindrical roller bearings with clearance and the other design using preloaded tapered roller bearings to support both the carrier and planet gears. Each design was developed and integrated into a 750 kW dynamometer tests, the loads on each planet bearing row were measured and compared to finite-element models. Bearing loads were not equally shared between the set of cylindrical roller bearings supporting the planets even in pure torque conditions, with one bearing supporting up to 46 % more load than expected. A significant improvement in planetary bearing load sharing was demonstrated in the gearbox with preloaded tapered roller bearings with maximum loads 20 % lower than the gearbox with cylindrical roller bearings. Bearing life was calculated with a representative duty cycle measured from field tests. The predicted fatigue life of the eight combined planet and carrier bearings for the gearbox with preloaded tapered roller bearings is 3.5 times greater than for the gearbox with cylindrical roller bearings. The influence of other factors, such as carrier and planet bearing clearance, gravity, and tangential pin position error, is also investigated. The combined effect of gravity and carrier bearing clearance was primarily responsible for unequal load sharing. Reducing carrier bearing clearance significantly improved load sharing, while reducing planet clearance did not. Normal tangential pin position error did not impact load sharing due to the floating sun design of this three-planet gearbox.

A unified and simplified treatment of the non-linear equilibrium problem of double-row rolling bearings. Part 2: Application to taper rolling bearings supporting a flexible shaft

2003 ◽  
Vol 217 (3) ◽  
pp. 213-221 ◽  
Author(s):  
D Nélias ◽  
I Bercea
Keyword(s):  
Fatigue Life ◽  
Theoretical Model ◽  
Rolling Bearing ◽  
Rolling Bearings ◽  
Double Row ◽  
Face To Face ◽  
Flexible Shaft ◽  
Shaft System ◽  
Tapered Roller ◽  
Tapered Roller Bearings

A general theoretical model to analyse the internal interactions within various types of double-row rolling bearing was presented in Part 1 of this two-part paper. The performance of the rolling bearing model is shown here for a bearings-flexible-shaft system. Double-row tapered roller bearings (in a back-to-back or face-to-face arrangement) were chosen as support bearings. Investigations of the effect of shaft mounting on support bearings (cantilever or straddle arrangement) and on the effect of preload are presented and discussed. It is shown that, when an optimum value of preload or fatigue life of the bearing arrangement is expected, shaft bending cannot be ignored.

Fatigue life of tapered roller bearing subject to angular misalignment

2015 ◽  
Vol 230 (2) ◽  
pp. 147-158 ◽  
Author(s):  
Van-Canh Tong ◽  
Seong-Wook Hong
Keyword(s):  
Fatigue Life ◽  
Substantial Reduction ◽  
Roller Bearing ◽  
Loading Conditions ◽  
Angular Misalignment ◽  
Tapered Roller Bearing ◽  
Tapered Roller ◽  
Life Analysis ◽  
Tapered Roller Bearings ◽  
Fatigue Life Analysis

Angular misalignment, defined as the tilted angle between the outer ring and inner ring, is unavoidable in most applications of tapered roller bearings (TBRs) due to many potential causes such as shaft deflection, initial mounting error, bearing geometry inaccuracy, etc. The occurrence of TRB misalignment introduces considerable changes into the contact load and the pressure between rolling elements and the raceways and, thus, greatly influences the bearing life. However, few research results are available on the effects of angular misalignment in TRBs. This paper presents the fatigue life analysis for TRBs with consideration for angular misalignment effects. To this end, a mathematical TRB model is developed to provide a comprehensive fatigue life analysis for TRBs subjected to angular misalignment. The presented model is verified by comparing the estimated fatigue lives under several loading conditions with those from a reference program. Then, the effects of angular misalignment on the fatigue life of TRBs are evaluated systematically. The simulation results show the importance of TRB alignment for the investigated TRB by demonstrating that small amount of angular misalignment leads to a substantial reduction in the fatigue life of the TRB regardless of loading conditions. The results address the necessity of misalignment effects analysis for TRBs.

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