STIFFENER SKIN INTERACTIONS IN PRESSURE-LOADED COMPOSITE PANELS

The deflection and strain responses of pressure-loaded graphite-epoxy panels clamped on all four edges and stiffened by “T”-type stiffeners are presented and discussed. Attention is focused on the strains and strain gradients in the stiffener and skin in the region of stiffener attachment. The effects of overall stiffener stiffness, flange thickness, and overall skin stiffness on the responses are discussed. Pressure levels up to 1 atm are considered. Results indicate that geometric nonlinearities are important at these pressure levels. Furthermore, overall stiffener stiffness has a significant effect on panel response, particularly the out-of-plane deformation, or pillowing, of the skin. Flange thickness, while not influencing overall panel response, has a strong influence on the strains in the attachment region. To a lesser extent, skin stiffness influences the strains in the attachment region. Results also indicate that the interface between the skin and the stiffener experiences two components of shear stress, in addition to a normal (peel) stress. This indicates that the skin/stiffener interface problem is threedimensional in nature. © 1990 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.