On the use of double-double design philosophy in the redesign of composite fuselage barrel components

Mass minimization and mechanical performance maximization constitute the basic aspects of the structural optimization processes. In particular, the laminate redesign in terms of thickness and lay-up grants the main approach for the optimization of composite components. The innovative Double-Double laminate concept provides an effective approach to design composite components for weight and strength requirements, overcoming the use of the conventional 0°, 90° and ±45° ply orientations. In Double-Double designed components, 4-plies building blocks are stacked one upon the other to constitute a laminate. Each building block is made up of four [±Φ, ±Ψ] oriented plies. In the present work, the Double-Double approach has been adopted in the redesign of the composite lay-up and thickness profile of frames in a composite fuselage barrel. The DD optimized frames achieved a total mass reduction by up to 35% while ensuring mechanical performances comparable to the starting configuration.