Rolling Contact Fatigue Life and Spall Propagation Characteristics of AISI M50, M50 NiL, and AISI 52100. Part 2. Stress Modeling (Preprint)
AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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This is the second part of three-part series that investigates the rolling contact fatigue initiation and spall propagation characteristics of three bearing materials, namely AISI 52100, VIM-VAR M50, and VIM-VAR M50NiL steels. A systematic investigation of effects of rolling contact fatigue RCF on evolution of material properties and micro-structural changes resulting in spall propagation rate has not been conducted. As a first step toward understanding spall propagation, we present stress distribution in the neighborhood of a spall initiated by RCF by an indent on a hybrid 40mm ball bearing. Elastic and elastic-plastic subsurface stress fields are computed using finite element models that incorporate the full three-dimensional 3D ball-raceway geometry. The stress fields predicted indicate extensive yielding around the spall edges. The spall is shown to widen first axially across the width of the raceway, causing the ball to unload as it enters the spall. Effect of potential impact on the spall trailing edge is also considered. The proposed scenario involves repeated application of contact stress resulting from a combination of ball static and impact loads.
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