Recent Developments in the Design, Testing and Impact-Damage Tolerance of Stiffened Composite Panels

Abstract

Structural technology of laminated filamentary-composite stiffened-panel structures under combined in-plane and lateral loadings is discussed. Attention is focused on (1) methods for analyzing the behavior of these structures under load and for determining appropriate structural proportions for weight efficient configurations, and (2) effects of impact damage and geometric imperfections on structural performance. Recent improvements in buckling analysis involving combined in-plane compression and shear loadings and transverse shear deformations are presented. A computer code is described for proportioning or sizing laminate layers and cross-sectional dimensions, and the code is used to develop structural efficiency data for a variety of configurations, loading conditions, and constraint conditions. Experimental data on buckling of panels under in-plane compression is presented to validate the analysis and sizing methods and to illustrate structural performance and efficiency obtained from representative structures. Experimental results show that strength of panels under in-plane compression can be degraded by low-velocity impact damage. Mechanisms of impact-damage initiation and propagation are described. Finally, data are presented that indicates the matrix is a significant factor influencing tolerance to impact damage.