Quasi-static and dynamic compression of additively manufactured functionally graded lattices: Experiments and simulations

In this paper, quasi-static and dynamic compressive behaviors of functionally graded (FG) lattices made of stainless steel (SS 316L) by electron beam melting (EBM) were experimentally investigated. The FG lattice structures were body-centered cubic (BCC) lattices with uni-directional density grading and bi-directional density grading. Their performance was compared with that of uniform lattices of the same relative density. The experimental results showed that, as compared with the uniform and uni-directional density graded lattices, the novel bi-directional density graded lattices witnessed the highest plateau stress and energy absorption capacity at the considered loading conditions. The deformation pattern and the stress distribution of the structures during the crush were further studied using finite element modelling (FEM). The finite element modelling showed that the enhanced strength and energy absorption were related to the periodic collapse of graded structures corresponding to the density gradient strategy. Two parametric studies were conducted using the experimentally validated FEM models to examine the influence of density gradient on the dynamic response of FG lattices.