Answer
Groove deformation occurs when the axial load $P$ exceeds the compressive yield strength of the groove material, even if the retaining ring itself remains intact. This is common when high-strength steel rings are used in soft aluminum or plastic housings. The ring 'sinks' into the groove wall, creating a 'ramped' surface. As the load increases, this ramped surface creates a radial outward force that eventually pushes the ring out of the groove. The failure is analyzed using the formula for bearing pressure: $\sigma_b = P / (\pi \cdot D \cdot d)$. If $\sigma_b$ exceeds the housing yield strength, failure is imminent. The fix is to increase the groove depth $d$, use a harder housing material, or use a wider radial wall $b$ on the ring to spread the load.
