Explicit local buckling analysis of stiffened composite plates accounting for periodic boundary conditions and stiffener–plate interaction

The present contribution is devoted to the closed-form analysis of orthotropic plates under uniaxial uniform compressive load. The plates under consideration are stiffened by open-profile stiffeners in the longitudinal direction which represents a structural situation that is typical, e.g. for many aircraft parts such as tailplanes, wing covers or, at least in an approximate sense, fuselage sections. The analysis method explicitly accounts for periodicity properties of the given structural situation as well as for stiffener–plate interaction and is based on adequate displacement shapes for both the plate as well as the stiffeners in the form of simple polynomials and trigonometric functions. While the plates and the stiffener webs are treated as shear-rigid Kirchhoff-type plates, the stiffener flanges are modeled as Bernoulli-type beam elements in order to allow for a feasible solution of the problem. Using a Ritz-type approach, explicit expressions for the buckling loads are achieved which allow for a straightforward, efficient and yet reliable buckling analysis of stiffened composite panels. The excellent accuracy of the derived analysis method is established through comparison with the results by other authors and with results generated from the exact transcendental elasticity solution that is derived from the governing partial differential equations and the underlying boundary conditions. The characteristic buckling behaviour of stiffened composite plates is discussed for several representative plate-stiffener configurations.