The Cross Notched Roller Test - a novel strength test for ceramic rollers. Part I: Stress field and error analysis

Cylindrical ceramic rolling elements used in hybrid bearings often experience stresses on their surface in service, while strength limiting defects are generated on the surface during the manufacturing process. In order to adequately characterize the surface strength, a method based on the standardized “Notched Ball Test” was adapted. For the “Cross Notched Roller Test”, a narrow notch is cut in the center of the roller, parallel to the end faces. By applying compressive forces perpendicular to the notch, axial tensile stresses in the outer surface region of the roller are generated. Thus, this test is sensible to crack-like defects that are oriented perpendicular to the roller axis. In this work, the stress field, effective surface and volume of such specimens were analyzed through Finite Element Analysis for a practical relevant range of geometry- and material parameters. The influence of possible deviations from the ideal setup are quantified and discussed.