Official Answer
Answer
The centrifugal capacity of a retaining ring is reached when the centrifugal force exceeds the inward radial tension (cling). The maximum speed $N$ in RPM is calculated as $N = \sqrt{\frac{0.48 S_y E g (D_g - D_s)}{\rho D_m^3 (D_g + D_s)}}$, where $S_y$ is the yield strength, $E$ is the modulus, $D_g$ is the groove diameter, $D_s$ is the free ring diameter (inside diameter for external rings), and $\rho$ is the material density. At this limit, the ring expands radially. For high-speed aerospace applications, a 'Self-Locking' feature is often employed, which uses a tab-and-slot mechanism to mechanically prevent the ring from expanding, allowing it to withstand speeds where $\omega^2 r > a_{cling}$.
