Additive manufacturing enables innovative structural design for industrial applications, which allows the fabrication of lattice structures with enhanced mechanical properties, including a high strength-to-relative-density ratio. However, to commercialize lattice structures, it is necessary to define the designability of lattice geometries and characterize the associated mechanical responses, including the compressive strength. The objective of this study was to provide an optimized design process for lattice structures and develop a lattice structure characterization database that can be used to differentiate unit cell topologies and guide the unit cell selection for compression-dominated structures. Linear static finite element analysis (FEA), nonlinear FEA, and experimental tests were performed on 11 types of unit cell-based lattice structures with dimensions of 20 mm × 20 mm × 20 mm. Consequently, under the same relative density conditions, simple cubic, octahedron, truncated cube, and truncated octahedron-based lattice structures with a 3 × 3 × 3 array pattern showed the best axial compressive strength properties. Correlations among the unit cell types, lattice structure topologies, relative densities, unit cell array patterns, and mechanical properties were identified, indicating their influence in describing and predicting the behaviors of lattice structures.

This study proposed an optimization framework and methodologies to design edgeless lattice structures featuring fillet and multipipe functions. Conventional lattice structures typically experience stress concentration at the sharp edges of strut joints, resulting in reduced mechanical performance and premature failure. The proposed approach aimed to improve the compression behavior of lattice structures by introducing edgeless features. Through finite element analysis, the optimized fillet edgeless simple cubic unit cell with a fillet radius to strut radius ratio of 0.753 showed a 12.1% improvement in yield stress and a 144% reduction in stress concentration. To validate the finite element analysis, experimental compressive tests were conducted, confirming that the introduction of edgeless functions improved the compressive strength of lattice structures manufactured through additive manufacturing. The optimized fillet edgeless simple cubic lattice structure exhibited the most effective improvement. This approach has promising potential for lattice structure applications.

Behaviors associated with the mechanical responses of a Kelvin unit cell can be improved by optimizing the parameter sets. Herein, we present a shape control method for a Kelvin unit cell by functionalizing the coordinates of 24 vertices. Further, we verified the physical properties of Kelvin lattice structures using relative density and lattice patterning through finite element analysis (FEA). Consequently, we devised a design method for the Kelvin unit cell that can control the cell aspect ratio. Furthermore, we estimated the relative density using the strut section and interior angles of a hexagon as variables, and achieved an accuracy of 96.3–99.7%. The FEA results revealed that with an increase in the relative density of the 1 × 1 × 1 lattice structure of titanium alloy to 0.00800, 0.03065, 0.11194, 0.22789 and 0.36246, the yield strength sharply increased to 0.67, 2.79, 10.23, 27.27 and 51.82 MPa, respectively. When the 1 × 1 × 1, 2 × 2 × 2, 3 × 3 × 3 and 4 × 4 × 4 lattice structures were configured with $H,W=20\sqrt{2}$ mm, the yield strength of the lattice structure converged in the 3 × 3 × 3 pattern.

Binder jetting 3D printing (BJ3DP) is used to create geometrical and topology-optimized building structures via architectural geometric design owing to its high degree of freedom in geometry implementation. However, building structures require high mechanical and durability performance. Because of the recent trend of using 3D printing concrete as a structural component in reinforcing bars, its durability with respect to chloride penetration needs to be reviewed. Therefore, in this study, the compressive strength and durability of the chloride diffusion of cement-based 3D-printed output were evaluated. In addition, to confirm the performance difference based on the build orientation, the compressive strength and chloride diffusion were evaluated with respect to the build direction and transverse direction. The experimental results show that the compressive strength was approximately 22.1–26.5% lower in the transverse direction than in the build direction and that the chloride diffusion coefficient was approximately 186.1–407.1% higher in the transverse direction. Consequently, when a structure that requires long-term durability is produced using BJ3DP, it is necessary to examine the design and manufacturing methods in relation to the build orientation in advance.

Seong-Ryong Kim, Song Cheol Kim, Ki Byung Song, Kwang-Min Park, Dae Wook Hwang, Jae Hoon Lee, Sang Hyun Shin, Bong Jun Kwak, Young-Joo Lee. Ann Hepatobiliary Pancreat Surg 2021;25:342-8. https://doi.org/10.14701/ahbps.2021.25.3.342