Influence of Unit Cell Size on Mechanical Properties of Lattice Structure

To understand the mechanical properties ol advanced lightweight multifunctional materials with a lattice structure, the body-centered cubic unit cell lattice structure prepared by selective laser melting was taken as an example to reveal the influence of the unit cell size on the mechanical properties of the lattice structure. Firstly, the mass of the lattice structure was measured by the dry weight method, the porosity was calculated, and the influence law of unit cell size on porosity was studied. Then, the evolution law of mechanical properties of lattice structure was studied through compression testing, compression-compression fatigue testing and scanning electron microscope fracture topography. The results showed that the actual porosity of all samples was lower than the design value. When the unit cell size was 2. 5 mm, the actual porosity showed a maximum deviation of 8. 2% from the design value. However, when the unit cell size was 7. 5 mm, the deviation was the smallest (1. 6%). As the unit cell size increased from 2. 5 mm to 7. 5 mm, the compressive strength of the lattice structure decreased by 41. 96%, indicating that the ability of the lattice structure to resist compression deformation became smaller, and the plasticity became worse. In addition, the fracture mechanism changed from plastic fracture to brittle fracture, and the number of fatigue cycles decreased. The transient zone was mainly composed of dimples when the unit cell size was small while it displayed a smooth plane and a small amount of dimples when the unit cell size was large, indicating that the lattice structure was more brittle. The research results can provide a reference for the design and selection of the unit cell size of the lattice structure. © 2023 Xi'an Jiaotong University. All rights reserved.