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Relation Between Residual and Hoop Stresses and Rolling Bearing Fatigue LifeRolling-element bearings operated at high speed or high vibration may require a tight interference fit between the bore of the bearing and shaft to prevent rotation of the bearing bore around the shaft and fretting damage at the interfaces. Previous work showed that the hoop stresses resulting from tight interference fits can reduce bearing lives by as much as 65 percent. Where tight interference fits are required, case-carburized steel such as AISI 9310 or M50 NiL is often used because the compressive residual stresses inhibit subsurface crack formation and the ductile core inhibits inner-ring fracture. The presence of compressive residual stress and its combination with hoop stress also modifies the Hertz stress-life relation. This paper analyzes the beneficial effect of residual stresses on rolling-element bearing fatigue life in the presence of high hoop stresses for three bearing steels. These additional stresses were superimposed on Hertzian principal stresses to calculate the inner-race maximum shearing stress and the resulting fatigue life of the bearing. The load-life exponent p and Hertz stress-life exponent n increase in the presence of compressive residual stress, which yields increased life, particularly at lower stress levels. The Zaretsky life equation is described and is shown to predict longer bearing lives and greater load- and stress-life exponents, which better predicts observed life of bearings made from vacuum-processed steel.
Document ID
20160000345
Acquisition Source
Glenn Research Center
Document Type
Technical Memorandum (TM)
Authors
Oswald, Fred B. (NASA Glenn Research Center Cleveland, OH, United States)
Zaretsky, Erwin V. (NASA Glenn Research Center Cleveland, OH, United States)
Poplawski, Joseph V. (Poplawski (J. V.) and Associates Bethlehem, PA, United States)
Date Acquired
January 6, 2016
Publication Date
December 1, 2015
Subject Category
Mechanical Engineering
Report/Patent Number
E-17726-1
GRC-E-DAA-TN18741
NASA/TM-2015-218893
Funding Number(s)
WBS: WBS 432938.11.01.03.06.02.06
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
Fatigue
Hoop stress
Rolling bearing

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