Official Answer
Answer
Fatigue failure in wave springs usually manifests as a clean, brittle-looking fracture starting from the ID of a wave peak or valley. Microscopic examination (SEM) will typically reveal 'striations' indicating the cyclic nature of the crack growth. The initiation point is usually a surface defect or a region of high tensile stress. To diagnose, one must calculate the stress range $Δσ = σ_{max} - σ_{min}$. If this range exceeds the endurance limit on a Goodman or S-N diagram, fatigue is inevitable. Troubleshooting involves reducing the deflection stroke, increasing the number of waves $n$ (to reduce the stress per wave), or switching to a material with a higher fatigue limit like 17-7PH instead of carbon steel.
