Experimental investigation of build orientation effects on mechanical and fracture behaviors of additively manufactured lattice materials

Build orientations affect the fracture behavior of lattice materials fabricated by material extrusion additive manufacturing under three fracture mode loading conditions. This study aims to evaluate the mechanical and fracture behavior of lattice structures made of environmentally-friendly, biodegradable Polylactic acid (PLA) using tensile dogbone, single-edge notched bending (SENB), and transverse shear cracked plate (TSCP) specimens. Two lattice types, body-centered cubic (BCC) and face- and simple-centered cubic (FSCC), were modeled and fabricated in three build orientations (horizontal, lateral, and vertical) for tensile and mode I, II, and III tests. The experimental data, including load-displacement responses, failure types, and fracture surface morphologies, were extracted in accordance with relevant standards. Then, the results of different build orientations were compared to each other in order to find a selected build orientation for each mode of fracture, by which we can experience the expected fracture behavior under the relevant loading type. The expected fracture modes were achieved in specific build orientations: vertical for dogbone, vertical for mode I SENB, horizontal for mode II SENB, and vertical for mode III TSCP specimens. Owing to FSCC’s symmetric architecture and strategic strut placement, the FSCC lattice demonstrates promising potential for use in high-performance lattice applications requiring fracture resistance.