Fracture behavior of octet-truss lattice structures under offset loading

The octet-truss lattice structure is characterized by its lightweight, high strength, and high specific stiffness, making it one of the preferred materials in engineering fields such as aerospace and automotive industries. Three-point bending experiments were conducted to examine the failure modes of specimens under offset loading to investigate the fracture behavior of the beam type octet-truss lattice structure under offset and central loading conditions. The influence of relative density on the fracture resistance of the structure under offset loading was analyzed. Using finite element simulation, the deformation modes of different planar members were studied, and the impact of rod length changes on the structure's fracture behavior was predicted. The study results indicate that, compared to central loading conditions, the ultimate load-bearing capacity under offset loading conditions increases by approximately 44.3%, while also exhibiting a longer plastic phase. Cracks propagate layer by layer within the structural units, and there are significant differences in the stress states of members in different planes. Notably, members in the Y-Z plane do not exhibit fracture. Additionally, under offset loading conditions, increasing the relative density significantly enhances the fracture toughness of the structure, while increasing the rod length extends the deformation phase of the structure.