Fabrication and mechanical evaluation of lattice structures for developing a lumbar support brace

This study aims to explore and select a sample of three-dimensional (3D) printed lattice structures suitable for fabrication of a lumbar brace. In particular, the study compared honeycomb, gyroid, and X-shape lattice structures. Thirty-six samples with two thicknesses, two pattern repeats, three lattice structures, and three 3D printing manufacturing methods and material variables were fabricated to evaluate tensile strength, flexural strength, weight, and density. Mechanical evaluation revealed that the tensile and flexural strengths of the honeycomb structure were higher than those of other structures. In addition, the fused deposition modeling (FDM) method using thermoplastic polyurethane (TPU) material had higher tensile and flexural strengths compared with the other two printing methods and materials. The honeycomb structure weighed the most, followed by the X-shape and gyroid structures. The sample made of PolyJet method with Agilus material showed higher values of weight and density than the other samples. Based on the experimental results, it is considered that TPU material, FDM, and selective laser sintering printing methods are suitable for production of the lumbar support brace because it is flexible and allows body movement but has moderate strength and density. By adjusting the pattern repeat and thickness of the lattice structure variable, we can determine the structure that is most suitable for lumbar support. Considering the lightweight requirements of lumbar support, future studies should devise ways to improve the lightweight properties of samples.