On an Innovative Optimization Approach for the Design of Cross-section Profiles of Integrally Stiffened Panels Subjected to Elasto-plastic Buckling Deformation Modes

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.