Strength of 7075-T6 and 2024-T3 aluminum panels with multiple-site damage

Much attention has been given to the development of technology for the purpose of determining the strength of aluminum panels that have multiple-site damage. The linkup model has been investigated because of its simplicity, and a number of modified linkup models have been presented. However, most of the attention has been given to 2024-T3 aluminum. Little attention has been given to 7075-T6 because it is a more brittle material with lower fracture toughness, making it more suitable to be analyzed by conventional linear elastic brittle; fracture mechanics technology. The work presented here involves the study of 7075-T6 panels with multiple-site damage. Both the classical linear elastic fracture model and the linkup model are shown to be highly inaccurate. A modified linkup model and a modified brittle fracture model have both been developed by empirical analysis. Both of these models appear to have a high degree of accuracy over a wide range of crack geometry. The modified linkup model for 7075-T6 is then compared with a previously developed modified linkup model for 2024-T3. This comparison shows that 2024-T3 panels with multiple-site damage have greater strength than 7075-T6 panels, especially for panels with small ligament lengths.