Strength of Stiffened 2024-T3 Aluminum Panels with Multiple Site Damage

Two modie edlinkup modelsweredevelopedfordetermining thecritical stressbased on linkup (ligamentfailure ) of2024-T3aluminumpanelswithmultiplesitedamage.ThesemodelsweredevelopedforusewithstandardMilitary Handbook for Metallic Materials and Elements for Aerospace Vehicle Structures (MIL-HDBK-5G )yield strength values. For this investigation, ligament failure stresses predicted by these models are compared with test stresses determined from a variety of stiffened panels including single-bay panels with the lead crack centered between stiffeners and two-bay panels with the lead crack centered beneath a severed stiffener. The stresses predicted by the modie ed linkup models correlate well with the test data. The results of this investigation should add to the understanding of the extent to which nonlinear behavior can be modeled with simplie ed engineering models. Nomenclature a = lead crack half-length an = nominal lead crack half-length c = multiple site damage (MSD) crack length D = hole diameter Fcol = collapse stress ` = half-length for MSD crack and hole, cC D/2 L = ligament length t = panel thickness tS = stiffener thickness W = panel width WS = stiffener width