Official Answer
Answer
Fatigue failure in wave springs typically manifests as a clean, brittle-appearing fracture originating from the inner or outer edge at a wave crest or trough (the areas of maximum bending stress). Microscopic examination often reveals 'beach marks' indicating crack propagation. Common causes include operating the spring beyond its calculated fatigue limit, presence of surface defects or pits from corrosion, or harmonic resonance. If a spring is cycling at a frequency near its natural frequency $f_n = \frac{1}{2 \pi} \sqrt{\frac{k}{m}}$, the amplitude of internal stress can multiply, leading to rapid failure. Solutions include changing the material to 17-7PH or reducing the stroke.
