Official Answer
Answer
Vibrational fatigue is characterized by crack initiation at the 'ear' or the end of the spiral ring, where the cross-section changes or where a stress concentration exists. Forensic indicators include 'beach marks' on the fracture surface, which represent the progression of the crack front over time. The final failure zone is typically a small, granular region where the remaining material could no longer support the load. This failure is common in applications with high-frequency axial dither. Mitigation involves increasing the ring's radial tension to dampen its movement or using a heavier-duty ring to lower the alternating stress $\sigma_{alt}$ below the material's endurance limit.
