Two-Scale Lightweight Optimization by Infilling Optimized Organic Truss-Based Lattice Material Based on the Principal Stress Trajectories

The use of minimal material to generate high-stiffness structures is a key goal for reducing material waste and mitigating environmental corrosion in the context of additive manufacturing (AM). This paper proposes a two-scale lightweight optimization approach that infills organic truss-based lattice material within the topology optimization framework to improve structure stiffness. The proposed method utilizes the Subdivision Surface (Sub-D) modeling method to efficiently model organic lattice morphology on the mesoscale level, reducing stress concentration and improving material performance. On the macroscale, topology optimization is used to refine a structurally effective design frame. Guided by the principal stress field of the refined shape, the part of the design domain is tessellated into conformal subdomains where optimized material is smoothly connected and infilled for high stiffness. The proposed method maximizes material efficiency by populating anisotropic lattice materials in a quality morphology from topology optimization. Challenges such as the shortfall of uniform lattice material mapping, the limitation of only porous lattice material, and geometric constraints and stress concentration on lattice units are addressed, with a solid-lattice hybrid structure as an effective solution. The proposed method presents a viable solution for lightweight optimization in AM-based design.