The Cross Notched Roller Test - A novel strength test for ceramic rollers. Part II: Experimental procedure and results

In order to adequately characterize the surface strength of ceramic rollers, a novel method is presented. For the “Cross Notched Roller Test”, a 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, which was not possible with any other strength testing method so far. In this work, the practical aspects of this method are discussed. This includes a comparison of three testing fixtures (symmetric and asymmetric in terms of load/support conditions), statistical analysis of strength results and fractographic analysis. Both experimental as well as numerical results have shown that asymmetric setups introduce ill-defined shear stresses and lead to an overestimation of roller strength in the range of 10%.