14.3.7. Cumulative Damage

Once the number of cycles to failure is determined using the selected life criteria (S-N curve), the damage of cycle can then be calculated by:

\({{D}_{i}}=\cfrac{1}{{{\left( {{N}_{f}} \right)}_{i}}}\)

The total damage of “event” of time history can be calculated by summing up the damage caused by each cycle according to the Palmgren-Miner’s rule

\(\text{Damage}=\sum{{D}_{i}}\)

The total number “event” to failure is

\(N=\cfrac{1}{\text{Damage}}\)