If you'd like to dive deeper into the topic, here are some PDF resources:
[ D_WL = \rho(k, \gamma) \cdot D_NB ]
While spectral methods are powerful, standard literature notes several limitations: vibration fatigue by spectral methods pdf
Situation : A suspension control arm subjected to random road excitation (PSD of vertical acceleration). Spectral result : Dirlik’s method predicts 2.3×10⁶ cycles to failure at 99% reliability. Comparison : Time‑domain rainflow on a 5‑minute signal gives 2.1×10⁶ cycles – a 9% difference, but spectral analysis took 0.2 seconds vs. 180 seconds for time simulation. If you'd like to dive deeper into the