Official Answer
Answer
Shear failure of the ring itself is rare and characterized by a clean, $45°$ or vertical 'shear lip' across the entire radial wall of the ring, with the ring remaining in the groove but 'sliced' into two or more layers. 'Groove Yield' is more common and is characterized by the ring being ejected from the groove, while the groove itself appears 'mushroomed' or flared out. Shear failure only happens when the groove and the retained part are both extremely hard (e.g., HRC $50+$), allowing the full axial force to act as a 'guillotine' on the ring. This is solved by increasing the ring's thickness $T$ or the number of turns.
