On the use of Double - Double advanced materiai processing for the design of a composite fuselage barrel.

Nowadays, the problem of pollution is strongly considered in the transportation industry, which is one of the major contributors to fuel emission and, therefore, to global pollution. In the aeronauti­ca! field, the legislation on exhaust emissions is becoming increasingly severe, hence, the reduction of airplane structural weight is seen as one of the possible solutions to decrease the fuel consumption and emissions for future vehicles. To improve lightweight aerospace design, metallic components are expected to be replaced by composite parts (mainly Carbon Fibre Reinforced Polymers), resulting in structures with superior performances and considerably lower weight. Despite the real potential, in terms of weight/stiffness and weight/strength characteristics, of composite materials, the classica! de­sign approach, which assumes symmetric and balanced laminates, stili have major limitations. Hence, in this paper, the new family of Double-Double (DD) laminates [1-2], characterized by an homoge­nized mechanical behaviour, arbitrary choice of lamination angles and easy of production, are used to redesign a composite fuselage barrel starting from a traditional [0,90,+45-45]ns quad composite stack­ing sequence. The Lam search optimization tool [2-4] in combination with A Finite Element platform has been used to find the best DD angles configuration and the best thickness distribution fulfilling the strength requirements and considerably reducing the structural weight if compared to the standard composite quad design approach.