What causes 'Ring Flutter' in spiral retaining rings and how does it lead to premature groove wear?

Ring flutter is a high-frequency axial oscillation of the ring within its groove, typically caused by reciprocating loads or fluid pressure pulses (e.g., in hydraulic valves). If the groove width $w$ is significantly larger than the ring thickness $t$, the ring can bounce between the groove walls. This constant impact causes 'peening' of the groove and can lead to work-hardening and subsequent cracking of the ring itself. To solve this, engineers should specify a 'light-series' wave spring to be installed behind the retaining ring, which provides a constant axial preload, effectively 'clamping' the ring against one side of the groove to eliminate flutter.