Structural Response of a Stitched Composite Hybrid Wing Body Center Section

Abstract

Hybrid wing body is a fuel-efficient aircraft configuration where the pressurized center section is confined by almost-flat panels jointed at right angles. The combination of internal pressure and in-plane loads imparts cyclic large out-of-plane deformations to the noncircular fuselage. These repeated pressure loads would lead to separation between the skin and flanges and delaminations in traditional layered composite structure. To address this challenge, researchers at NASA and The Boeing Company selected the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept, an integrally stiffened panel design that is stitched together and designed to maintain residual-load-carrying capabilities under a variety of damage scenarios. Analytical and experimental results of the structural response of an all-composite 80%-scale hybrid wing body center section are presented herein. Internal pressure and mechanical loads representative of flight loads and certification requirements were imparted to the pristine and damaged structure. The pristine structure, the structure with barely visible impact damage, and the structure with discrete source damage all supported design ultimate load and displayed significant nonlinear response. Based on comparison with the test data, the finite element analysis performed before testing accurately predicted deformations, strains, and onset of localized buckling for the load cases considered.