INHERENT MATERIAL BEHAVIOR AND WIDESPREAD FATIGUE

摘要

In aging aircraft, large flaws and defects have most likely already been discovered. However, fatigue cracks can form at inherent material defects and contribute to widespread fatigue damage, particularly for structures having accumulated a large number of cycles. We have developed a probabilistic life prediction model based on fatigue cracks forming at the inclusion particles inherent to rolled aluminum sheet. Using the particle size distribution as the flaw size distribution and a deterministic crack growth model, good agreement between experimental and predicted fatigue lives was observed for notched test specimens of 2024-T3 and 7075-T6 aluminum alloys. The model predicts the distribution of the fatigue lives. It can also be directly incorporated into risk analysis programs.