Structural response and failure of a full-scale stitched graphite-epoxy wing

Analytical and experimental results of the test for an all-composite full-scale wing box are presented. The wing box is representative of a section of a 220-passenger commercial transport aircraft wing box and was designed and constructed by The Boeing Company as part of the NASA Advanced Subsonics Technology program. The semispan wing was fabricated from a graphite-epoxy material system with cover panels and spars held together using Kevlar stitches through the thickness. No mechanical fasteners were used to hold the stiffeners to the skin of the cover panels. Tests were conducted with and without low-speed impact damage, discrete source damage, and repairs. upbending, downbending, and brake roll loading conditions were applied. The structure with non-visible impact damage carried 97 percent of design ultimate load before failure through a lower cover panel access hole. Finite element and experimental results agree for the global response of the structure.