Skin-Stiffener Stresses in Composite Plates and Shallow Shells

The development of an approximate analysis for predicting stresses in the skin-stiffener interface region of composite plates and shallow shells is presented. The analysis determines interlaminar normal stress and transverse shear stresses in the direction of the stiffener axial coordinate and the direction of the in-plane coordinate perpendicular to the stiffener axis. The analysis accounts for skin-stiffener interfaces with nonzero thickness and for curvature in the skin and stiffener. The interlaminar normal stress and transverse shear stresses at the interface are applied to the lower face of the skin and the upper face of the stiffener flange as unknown functions, and the displacements in the skin and flange are related through the deformation of the interface bond layer. The Rayleigh-Ritz method is used to determine the unknown functions that yield the interlaminar stresses at the skin-stiffener interface. Distributions of the interface stresses are presented, and these results show that the stresses are greatest at the edge of the stiffener flange. In addition, results from the skinstiffener analysis have been compared with results from other analyses, and all of these results were found to be in close agreement.