Official Answer
Answer
Dishing occurs when the axial load $P$ creates a moment $M = P \cdot (b/2)$ that twists the ring's cross-section. This is exacerbated if the groove walls are not perpendicular or if the groove has a large radius at the bottom. The resistance to dishing is proportional to the material's modulus $E$ and the thickness $t$ cubed. If the ring dishes, it reduces the contact area with the groove, leading to premature failure of the groove edge. To mitigate this, engineers specify a maximum groove radius of 0.1 times the thickness and ensure the groove depth $d$ is sufficient to support at least 70 percent of the ring's radial wall $b$.
