Design and mechanical characterization of lightweight lattice structures based on topology optimization

To overcome the limitation that conventional lattice structures rely on predefined unit-cell configurations and cannot achieve reasonable material distribution under specific loading conditions, this paper proposes a design and mechanical characterization method for lightweight lattice structures based on topology optimization. Unlike existing studies that mainly focus on specific unit-cell configurations or single boundary conditions, this work employs the Solid Isotropic Material with Penalization (SIMP) topology optimization method under various single and combined loading boundary conditions to design six lattice configurations. Ti-6Al-4V lattice specimens are then fabricated via Selective Laser Melting (SLM) additive manufacturing technology. By combining quasi-static compression experiments with finite element simulations, the compressive deformation behavior, failure mechanisms, stress-strain responses, and energy absorption performance of different configurations are systematically investigated. The results show that the boundary conditions used in topology optimization significantly affect the load transfer paths and failure modes of the lattice structures. Among them, the force on six faces (SFF) configuration exhibits early localized instability due to stress concentration at the pore edges, whereas the force on twelve edges (TEF), SFF + TEF, and Force on eight nodes (ENF) + SFF configurations show more stable cooperative deformation capability because of their multi-path load-bearing struts. The SFF + TEF configuration achieves the best overall energy absorption performance, with the energy absorption and specific energy absorption reaching 7.688 MJ/m³ and 0.2688 MJ/(g·m³), respectively. Further analysis of array density shows that, under unchanged overall dimensions, increasing the number of arrays can enhance the load redistribution capability and improve compressive stability. This study provides a reference for the design of lattice structures for aerospace, automotive lightweighting, and other applications.