A small-load-omitting criterion based on probability fatigue

• Existing SLOCs are based on deterministic fatigue-damage evaluation.
• KL divergence is used to measure the difference between fatigue life distributions.
• Omission level is calculated by setting KL divergence equal to a tolerance value.
• Five different load spectra were tested to verify the SLOC in the present study.

A small-load-omitting criterion (SLOC) which is evaluated by whether the truncated spectrum has the same fatigue life probability distribution as the original spectrum is developed. Primary focus is placed on the uncertainties of fatigue properties and fatigue life. Probabilistic distance is used to measure the difference between two fatigue life probability distributions. The omission level can be obtained when the probabilistic distance is equal to a tolerance value predefined. Fatigue tests with smooth sheet specimens made of LC4CS Aluminum alloy are conducted to verify this criterion. It is found that experimental results agree well with theoretical solutions.