Microstructural characteristics and mechanical properties of intelligently designed multiple-parameter Ti-6Al-4V lattice structure fabricated by selective laser melting

Lightweight lattice structures are widely desired in various engineering fields for their high stiffness-to-weight ratio and superior energy absorption capabilities. Compared with conventional body-centered cubic (BCC) single-parameter lattice structures (SPLS), the BCC multiple-parameter lattice structures (MPLS) enable better mechanical performance, since they provide more choices for geometric design. This study presents a novel BCC lattice structure with multiple-parameter intelligently designed by the surrogate-assisted particle swarm optimization (ESPSO) algorithm. Using Ti-6Al-4V alloy powder as the material, the as-designed MPLS are successfully fabricated by selective laser melting (SLM) in different build orientations, and the SPLS with the same material usage are also fabricated for a fair comparison. Their surface forming quality of both BCC SPLS and MPLS is excellent observed by ultra-depth of field microscopy. Subsequently, their mechanical properties are studied via quasi-static uniaxial compression testing. The results show that compared with the SPLS, the elastic modulus, yield strength, compressive strength, and energy absorption capacity of MPLS all exhibit a clear improving trend. Among three different building orientations of the MPLS, the 0° orientation exhibits the optimal mechanical properties, while the 45° orientation presents the best energy absorption capacity. The numerical simulation results accurately predict the fracture-deformation mechanism and mechanical properties of the lattice structure, with a prediction error of less than 15%. The mechanical properties of the optimized MPLS are significantly improved, endowing it with promising application prospects for the lightweight design of equipment structures in key fields such as aerospace,- vehicles, and biomechanical engineering.