Wide Panel Fracture Toughness Testing of Aluminum Lithium and Conventional Aluminum Alloys

Fracture toughness properties are a key factor in fuselage skin and lower wing skin design. For materials with a high toughness, wide panels are required to fully characterize the plane stress fracture toughness behavior. However, most industry data are based on testing performed using 16-inch or 30-inch wide panels.

A number of aluminum lithium options have been released in the last 10 to 15 years that appear to show good promise for low density options with high toughness. Similarly, advances have been made in conventional alloys with improved toughness.

In an attempt to optimize properties for use in new designs, plane stress fracture toughness testing was performed with middle tension panels up to 60 inches wide. This testing characterized the K values, R-curves and fracture mode for 6 different aluminum alloys: 2024, 2524, 2624, 2029, 2198 and 2199. The effect of panel width and thickness was also investigated. This presentation will show the results of this testing and discuss the hypotheses and conclusions reached thus far.