Abstract: Spheriform graded body-centered cubic(S-GBCC) is a lattice structure with better mechanical properties, and it can effectively improve the defects of conventional body-centered cubic(BCC) lattice structure, such as large joint stress and uneven beam force. However, its mechanical properties are affected by the cell size, the cross-sectional characteristics of the beam and the joint connection mode. Considering the geometric configuration of the variable cross-section beam and the connected sphere, the geometric topology analysis of S-GBCC lattice structure is completed. Based on the Timoshenko beam theory, the mechanical and mathematical models are established, and the functional relationships between the lattice size parameters and the relative density, equivalent elastic modulus, and equivalent yield strength are obtained. The S-GBCC lattice structure with different radius of curvature at the same relative density was prepared by selective laser melting(SLM) process. Based on the analysis of the morphologies of the printed samples with different specifications, the equivalent mechanical model of S-GBCC lattice structure considering the influence of forming accuracy is formed. The static compression test of lattice structure is completed to analyze its deformation characteristics and mechanical properties. Compared with the traditional BCC lattice structure, the mechanical properties of S-GBCC are significantly improved. The theoretical and experimental results are in good agreement, which verifies the accuracy of the model.

Key words: lattice structure, body-centered cubic, selective laser melting, equivalent mechanical model