ON AN INNOVATIVE OPTIMIZATION APPROACH FOR THE DESIGN OF CROSS-SECTION PROFILES OF INTEGRALLY STIFFENED PANELS SUBJECTED TO ELASTO-PLASTIC BUCKLING DEFORMATION MODES

Abstract

Aircraft fuselage panels are conventionally differential reinforced structures, with aluminum skin and stringers being conventionally joined by riveting operations. As a consequence, these structures can present a number of distinct components, making assembly operations time consuming and expensive. Recently, developments in aluminum extrusion have opened up possibilities for new design procedures for aircraft applications. Particularly, complex-section panels known as Integrally Stiffened Panels (ISP), which are reinforced structures integrally obtained from extrusion, are a good example. In structural terms, ISP may be considered as thin-walled structures in which the stability for compressive loads is strongly dependent on the buckling strength of the cross section itself. Besides the difficulties in the project for buckling deformation modes within the elasto-plastic range, in aeronautical design it is mandatory to find the best compromise between weight and structural performance.

In this sense, the present work presents an optimization algorithm based on a Hybrid Differential Evolution and Particle Swarm Optimization (HDEPSO) formulations, applied in finding the optimal cross section shape and dimensions for general ISP structures, under compressive buckling loads and accounting for elasto-plastic behaviors. The results and design guidelines are obtained by a set of parameterized nonlinear finite element simulations in ABAQUS, accounting for buckling carrying load levels as the principal design criteria.