Strength of 2024-T3 aluminum panels with multiple site damage

An aging aircraft ac cumulates fatigue cracks commonly referred to as multiple site damage (MSD). For ductile materials such as 2024-T3 aluminum,MSD cracks may lower the strength significantly below that which is predicted by conventional fracture mechanics or net section yield failure methods. An analytical model generally referred to as the linkup model (or the plastic-zone-touch model) has previously been used to describe the MSD phenomenon, However, the linkup model is only accurate for limited geometric configurations. Two modifications to the linkup model were developed through regression analysis of test data obtained from the literature and from experimental results conducted in this investigation. The modified models show significantly improved correlation with the test data over a wide range of configurations for flat 2024-T3 aluminum panels with MSD at open holes.