Failure analysis of rotating disks

Abstract Based on the plane elasticity solution, the size and the number of pie-sector shaped fragments produced at the failure of a rotating flat disk have been determined. In the analysis, it is assumed that a radial through-thickness crack has propagated from the bore to some extent, which could be due to the progressive growth of a pre-existing flaw under low-cycle fatigue loading. Taking the crack plane as the plane of symmetry and assuming that the crack length is critical, one-half of the disk has been analysed. At the onset of the unstable propagation of the assumed radial crack, a possible second failure location away from the original crack at the inside boundary of the disk has been determined. The size of the pie-sector shaped fragments as obtained in the analysis has been compared with the available experimental results [Sato and Nagai (1963), National Aerospace Laboratory, Tokyo, NAL TR-38 and NAL TR-47 (in Japanese)]. The results are in close agreement with the experiment. It is noted that, as the ratio of the inner radius to the outer radius of the disk increases, the number of fragments also increases, as it has been observed experimentally. The present analysis technique is suitable for disks having a smaller ratio of inside to outside radii.