Failure and energy absorption characteristics of four lattice structures under dynamic loading

Two novel diamond lattice structures (Dfcc and Dhex) and the typical face-centered cubic (FCC) and body-centered cubic (BCC) lattice structures are manufactured by selective laser melting (SLM), and the effects of cell topology and relative density on the dynamic behavior of these structures are studied through a combination of experimental tests and numerical simulation. It is observed that in Dfcc and Dhex, failure initiates at the connection points between rods in the middle of the structure, causing a sudden drop of the measured stress value. However in FCC and BCC, failure initiates in the face-truss junction. Generally, the FCC and BCC are dominated by stretching and bending of the rods respectively, whereas the Dfcc and Dhex are a mixture of the two deformation modes. The results show that the mechanical properties of the lattice structures with different relative density can be described by a power law function. Moreover, for the lattice structures with the same rod diameter of 0.8 mm, FCC out-performs other structures in terms of specific strength, specific modulus and energy absorption. This gives evidence that lattice structures with the stretching-dominated deformation mode are more likely to exhibit better mechanical properties under dynamic loading. Keywords: Lattice structures, Mechanical properties, Failure analysis, Energy absorption