Mechanical Properties and Failure Modes of Additively Manufactured Ti6Al4V Lattice Structures under Quasi-Static Compressive Loading

Additive manufacturing (AM) has many advantages over traditional manufacturing technologies as it allows the fabrication of lattice structures with complex designs and inherent features within a single part without any separation. Currently, lattice structures have wide application prospects due to their excellent mechanical performance and design freedom. This paper provides both experimental and numerical investigations for the failure behaviors of selective laser melting (SLM) Ti6Al4V lattice structures under uniaxial compressive loading. Lattice structures with different cell topologies and strut radii were chosen to conduct quasi-static compression simulations to examine their mechanical properties and failure modes. It is found that adding Z-direction struts in the loading direction could significantly improve the load-carrying capacity and the most superior mechanical properties were presented by FCCZ. The slopes of the double logarithmic relationship between the equivalent stiffness and the relative density of lattice structures can be distinguished as close to 1.0 and 3.0, implying bending-dominated or stretch-dominated behavior of lattice structures, respectively. For stretch-dominated lattice structures under uniaxial compression, FCCZ, BCCZ and FBCCZ, the failure modes would experience a transformation from strut buckling to fracture with the increase of strut radii, which is different from FCC and BCC demonstrated as the bending-dominated lattice structures.