Optimization of composite aeronautical components by Re-designing with double-double laminates

This paper introduces a novel approach to optimize aircraft structural design for enhanced performance and environmental sustainability. Traditional constraints on composite laminate stacking sequences, such as the symmetrical and balanced nature of classical quasi-isotropic laminates, often lead to over-dimensioning of aeronautical components. To overcome these limitations, the adoption of a new class of laminates known as Double-Double laminates, originally introduced by Prof. S.W. Tsai, is proposed. Unlike traditional laminates, Double-Double laminates offer flexibility in layer orientations, small building blocks, easy homogenization, and tapering capability. This study presents various case studies of increasing complexity to assess the effectiveness of the proposed methodology. First, a multicopter frame is redesigned to reveal the methodology's ability to reduce component weight while ensuring strength requirements under typical service loads. Then, the "DD Automated Design Tool", a newly developed Finite Element Method tool interfacing with the Lamsearch engine, is introduced. This tool facilitates the rapid identification of optimal composite double-double laminate layups based on material properties, applied loads, and boundary conditions. By iteratively interacting between the Finite Element Method software and the Lamsearch engine, the tool efficiently identifies the best laminate angles to meet specific strength requirements. To validate the weight-saving capability of the proposed methodology, the optimizations on a composite fuselage section and a real composite wing-box under realistic loading conditions have been carried out. Both cases resulted in significant weight reductions compared to initial configurations, demonstrating the effectiveness of Double-Double laminates in achieving structural efficiency and meeting performance demands.