Characterization of mechanical equivalent properties for node enhanced graded lattice structure

Considering the stress concentration at the rod connection of traditional body-centered cubic (BCC) lattice structure, a node enhanced BCC (NBCC) lattice structure was proposed. In recent years, graded lattice structure has gradually attracted attention due to their unique mechanical properties. In this paper, two different graded NBCC lattice structures were designed and their static mechanical properties were evaluated through quasi-static compression experiments and simulations. Moreover, homogenization theory was applied to calculate the equivalent modulus of lattice structure. This method was extended from uniform lattice structure to graded lattice structure by improving the application of periodic boundary conditions. The obtained results were in good agreement with the experimental and simulation data. The quasi-static compression tests demonstrated that NBCC can effectively reduce the stress concentration and improve the load-bearing capacity about 25% compared to BCC. The graded lattice structures exhibit varying mechanical properties depending on their design and present better mechanical performance in the anisotropic direction. Finally, the relative relationship between the equivalent elastic modulus and the equivalent shear modulus in the lattice structure was studied. The prediction formula for equivalent shear modulus was extended based on the Gibson-Ashby formula.