Experimental and Numerical Investigation of PLA Based Different Lattice Topologies and Unit Cell Configurations for Additive Manufacturing

Lattice structures are bio-inspired designs made up of repeated unit cells consisting of beams, surfaces, or plates that fit together in an ordered or stochastic fashion. These unit cells are configured according to their size and shape in three dimensions. Simple lattices can be created using standard manufacturing techniques such as computer numerical control machining, welding, and casting. Additive manufacturing enables customers to make complex structures with small features at a reasonable cost. In the present work, using octagon, hexagrid, and rhombic dodecahedron lattice topologies, characterized by unit cell size from 3 × 3 × 3 to 7 × 7 × 7 mm and strut thickness from 0.5 to 1.5 mm, the structural behavior of a solid cylindrical model made of polylactic acid material under compression is analyzed. Finite element analysis (FEA) through Autodesk® Netfabb® solvers was used to assess lattice structure mechanical and structural properties. The results were validated by physical compression testing on additively manufactured samples. Cellular designs with 3 × 3 × 3 mm unit cells and 1.5 mm strut thickness displayed the lowest Von Mises stress and deformation. For different topologies, lowest results were rhombic dodecahedron (stress through FEA as 61.3108 MPa and stress through physical test as 61.05 MPa, deformation through FEA as 0.49921 mm and deformation through physical test as 0.48 mm), octagon (stress through FEA as 77.4147 MPa and stress through physical test as 76.92 MPa, deformation through FEA as 0.53316 mm and deformation through physical test as 0.51 mm), and for hexagrid (stress through FEA as 62.2911 MPa, stress through physical test as 62.15 MPa, deformation through FEA as 0.81997 mm and deformation through physical test as 0.81 mm). The percentage error between the stress through FEA and stress through physical test for octagon, hexagrid, and rhombic dodecahedron lattice topology was found out to be 0.63, 0.22, and 0.43