Cumulative fatigue damage D = Σ n_i / N_i. Failure predicted at D = 1.
Formula
$$ D = \sum_i \frac{n_i}{N_i} $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $n_i$ | Actual cycles at stress level i | - | spectrum analysis |
| $N_i$ | Allowable cycles from S-N curve | - | DNV-RP-C203 |
| $D$ | Cumulative damage | - | result |
Sources
- Miner (1945) - Cumulative damage in fatigue.
- DNV-RP-C203 - Fatigue design.