Compression and Deformation Behaviors of Hierarchical Circular-Cell Lattice Structure with Enhanced Mechanical Properties and Energy Absorption Capacity

The design of lightweight lattice structures with excellent specific mechanical properties has received great attention in recent years. In this paper, inspired by the hierarchical structure of biological materials, a novel hierarchical circular-cell configuration of a lattice structure was proposed. The advantage of the new lattice configuration is that the use of a smooth circular cell is able to alleviate the stress concentration induced by the intersection of straight struts. Additionally, the consideration of structural hierarchy can bring improved mechanical properties of lattice structures. The hierarchical circular lattice structures with 5 × 5 × 5 unit cells were fabricated through a digital light processing (DLP) 3D printer, using the hard-tough resin. The mechanical properties of the lattice structures were investigated by a compression experiment and a numerical simulation. Results show that the interaction effect of structural hierarchy was the potential mechanism for the enhancement of mechanical properties. The designed hierarchical circular-cell lattice structure exhibits improved stress distribution uniformity, enhanced mechanical performance, and energy absorption capacity. The maximum improvement values are ~342.4% for specific stiffness, ~13% for specific strength, ~126.6% for specific energy absorption (SEA), and ~18% for crash load efficiency (CLE). The developed hierarchical circular-cell lattice configuration will enrich the present lattice systems and be useful for future multifunctional applications.