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.