Experimental Investigation of the Spall Propagation Mechanism in Bearing Raceways

Abstract

This article investigates the spall propagation mechanism for ball bearing raceways by focusing on an experimental investigation of cracks that evolve in the vicinity of the spall edge. Understanding the spall propagation mechanism is an important step towards developing a physics-based prognostic tool for ball bearings. This research reflects an investigation of different spall sizes that propagate naturally both in laboratory experiments and in the field. By using a combined model of a rigid body dynamic model and a finite element model that simulates the rolling element–spall edge interaction, our results shed light on the material behavior (displacements, strains, and stresses) that creates an environment for crack formation and propagation. With the support of the experimental results and the rolling element–spall edge interaction model results, three stages of the mechanism that control fragment release from the raceway were identified. In Stage one, sub-surface cracks appear underneath the spall trailing edge. In Stage two, cracks appear in front of the trailing edge of the spall and, in Stage three, the cracks propagate until a fragment is released from the raceway. These stages were observed in all the tested bearings. In addition, other phenomena that affect the propagation of the cracks and the geometry of the fragment were observed, such as blistering and plastic deformation. We include an explanation of what determines the shape of the fragments.

New Damage Accumulation Model for Spall Propagation Mechanism in Bearing Raceways

“…In the first and third types of fragment release, the cracks may initiate simultaneously; however, sub-surface and surface cracks are more dominant, respectively. It is noteworthy to mention that all the experimental analyses of the spalls showed similar results, and also are supported by [ 14 , 18 , 29 , 30 ].…”

“…To examine this process, the impact location, , was varied, keeping the same normal contact load, , as calculated in the dynamic model. These impacts produce plastic compressive deformation that turn into residual tension ( Figure 6 and see [ 18 ]). For every different impact location, the residual maximum principal stress direction was extracted, and their direction and amplitude are shown in Figure 9 .…”

“…Several damage models (described in Section 2.1.3 ) and fracture mechanics tools (described in Section 2.1.4 ) were integrated into the FE model to examine the path of the cracks in the vicinity of the spall and compared with the experimental observations (presented in Section 3.1 ). For more details, see [ 18 ].…”

“…The pneumatic cylinder applied vertical load of 2200 N on the tested bearing, and the rotational speed of the shaft was 35 Hz. Additional details on the experimental setup and results are presented in [ 18 ]. Here, we present only relevant observations to the current research.…”

Wear Behaviors of the Surface of Duplex Cast Steel after the Burnishing Process

“…For this reason, many studies aim to analyze this phenomenon in order to help industries to minimize their maintenance costs. The topicality of the issue is confirmed by numerous publications on contact fatigue [24][25][26][27][28]. The results presented in this article are a continuation and extension of this research.…”