Official Answer
Answer
In applications like automotive valvetrains or high-frequency vibration isolators, if the excitation frequency matches the natural frequency ($f_n$) of the wave spring, resonance occurs. The natural frequency is $f_n = \frac{1}{2 \pi} \sqrt{\frac{k}{m}}$, where $m$ is the effective mass. Resonance causes the waves to oscillate with amplitudes much higher than the design deflection, leading to rapid fatigue failure. Symptoms include 'dancing' of the spring or localized wear on the ID/OD. To fix this, the spring rate $k$ or mass $m$ must be changed to shift $f_n$ out of the operating range, or damping must be introduced, often by using a nested wave spring where inter-turn friction dissipates the vibrational energy.
