Numerical simulation of crack propagation in lattice materials

Lattice material is an innovative structure providing a good range of strength and fracture in relative density with light weight. It allows many engineering fields such as manufacturing and construction to have more material structure options. One of the main advantages of using lattices is their high strength and fracture toughness at low densities. These unique characteristics have been studied for a long time, and it was found that the lattice topologies and relative density have a significant role in these characteristics. For further details on the correlation between lattice topology and relative density to fracture toughness, a PhD student, Omidi and Assistant Professor St-Pierre from Aalto University, conducted an experimental test on Compact Tension (CT) specimens of three lattice topologies. In this report, based on the result obtained from the experiment by Omidi, a finite element simulation was run to compare the failure behavior of cell-walls and the deformation behavior of lattices under tensile stress. Three lattice topologies were selected as Snub-Trihexagonal, Snub-Square, and Elongated-Triangular. Each topology had three relative densities of 0.2, 0.25, and 0.3. The results obtained from the simulation showed a very similar trend to the result from the experiment in the force-displacement graph. Their de-formation mode showed the same failure of cell-wall along the initial crack and deformation on the models in most cases. A few more simulations were run with different values in elastic modulus or failure strain for a few models with varying modes of deformation or a slight difference in the force-displacement graph. A slight change in the value obtained dramatic changes in results