Optimisation of variable material orientations through design subregions for additive manufacturing of fibre composites

Abstract

Abstract Additive manufacturing enables the production of structures conceived with optimal design freedom, realising the potential of conceptual gains. The design of composites with variable orientations, or variable stiffness design, holds unexplored potential for benefiting from optimisation techniques and additive manufacturing. This work presents an innovative two-level methodology for optimal design of variable stiffness composites. The methodology determines the shapes of design subregions on plate structures and sets of curves for optimal variable orientations, while allowing manufacturing by 3D printing. Structural compliance is minimised (i.e. structural stiffness maximised). In the first level, a material orientation design is determined point-wise over structural finite element meshes, using principal stress information. In the second level, optimal curve fittings are performed on the point-wise design obtained in the first level, and in subregions whose shapes are designed by the optimisation method. Parallel curves are employed as material paths, to enhance manufacturability. All cases yielded increased overall stiffness, which benefits from variable stiffness design. A particular example also shows potential for failure load increase. Manufacturing is possible for the outcomes of the introduced methodology, as successfully demonstrated by material extrusion 3D printing. The integrated design of subregions’ topology and variable material orientations, while delivering manufacturing feasibility, is the main contribution of the proposed method.