Answer
The groove must be deeper than the ring thickness $t$ and have sharp corners to minimize the moment arm of the applied thrust load. The standard allowable groove corner radius is typically $0.1$ mm to $0.2$ mm. If the groove is too shallow or has an excessive radius, the ring may 'dish' or undergo elastic deformation, leading to premature failure through a 'rolling' mechanism rather than pure shear. The shear strength of the ring is calculated as $P_s = D \cdot t \cdot \pi \cdot \tau_{ult}$, whereas the groove yield strength is $P_g = D \cdot d \cdot \pi \cdot \sigma_y / S$, where $d$ is the groove depth and $S$ is a safety factor. Ideally, the groove material (often softer than the ring) should be the limiting factor, designed to yield slightly to distribute the load.
