Urso E., Giunta G., Montemurro M.
Composite Structures, vol. 375, art. no. 119762, 2026
This work presents a novel method for the concurrent optimisation of both the topology and anisotropy field descriptors of variable-stiffness composite structures. The proposed approach employs a multi-level optimisation strategy based on Non-Uniform Rational Basis Spline (NURBS) entities, a density-based topology optimisation method, and the polar formalism to describe the anisotropy of the continuum. The use of NURBS entities allows representing the spatial distribution of density and polar parameters fields across the design domain. Furthermore, the properties of NURBS entities are efficiently exploited to automatically satisfy some technological constraints, like the continuity of the polar parameters across the domain and minimum length scale requirements. The proposed method is applied to the problem of maximising the structural stiffness, while fulfilling design requirements on the lightness and on the feasibility of the polar parameters. In this context, the problem is formulated in the most general scenario considering inhomogeneous Neumann–Dirichlet boundary conditions and design-dependent loads, such as gravity or centrifugal forces. The effectiveness of the methodology is evaluated using benchmark problems taken from the literature, by considering the most general case of simultaneous optimisation of topology and anisotropy of the continuum. Particularly, a large campaign of sensitivity analyses has been carried out to investigate the impact of integer parameters of the NURBS entity, the penalty schemes used for the element stiffness matrix and the vector of design-dependent loads, as well as inhomogeneous Neumann–Dirichlet boundary conditions and initial guess on the optimised solution.
