Effective elastic properties and initial yield surfaces of two 3D lattice structures

The effective elastic properties of two bending-dominated lattice structures subjected to uniaxial loading are investigated with using the classical beam theory. In particular, considering the coupling effect of axial force and bending moment, a theoretical approach for predicting the yield surface of lattice structures under complex stress state is proposed. The analytical solutions are verified by comparing the predictions with finite element method (FEM) simulations. It is shown that the deformation mode of the struts is strongly dependent on the loading directions, and the lattice can be either bending-dominated or stretching-dominated in different stress states, resulting in narrow yield surfaces. The comparisons reveal that both the theoretical analysis and numerical simulations present a considerably good description of the initial yield surfaces, which provides new insight into understanding the mechanical behaviors of the lattice structures and applications in lightweight structures.