Flexural Properties of Periodic Lattice Structured Lightweight Cantilever Beams Fabricated Using Additive Manufacturing: Experimental and Finite Element Methods.

ABSTRACT

Lattice structures are a type of lightweight structure that is more commonly being applied to engineering systems as a way to reduce mass and enhance mechanical properties. The cantilever beam case is one of the primary modes of loading in many engineering applications, where light-weighting is also crucial. However, lightweight lattice structured cantilever beams have not been investigated considerably due to design and manufacturing limitations. Therefore, the aim of this study was to investigate the response of four different lattice structured cantilever beams comprising of unit cells made from Schwarz-P, Schwarz-D, Gyroid, and Octet-truss structures fabricated using Multi Jet Fusion additive manufacturing technology. An investigation into the cross-sections of these structures leads to a conclusion that the beams made from such structures are non-prismatic in nature as a result of variation in cross-sections. This led to the development of equations for the moment of inertia of these structures, which helped in calculating symmetric and un-symmetric bending. These beams were subjected to cantilever loading until failure, which provided insights into flexural properties such as flexural stress, stiffness, and strain energy. Experimental results indicate that the surface-based structures, due to better surface-area-to-volume ratio, have better ability in transferring loads and hence perform better than the beam-based Octet-truss beam. The Schwarz-D beam had performed the best among all the beams, which is further supported in literature due to its stretch-dominated topology that results in higher values of modulus. The finite element analysis (FEA) findings also validate these findings in which the distribution of stresses can be seen to be better transmitted than the other structures. The FEA validation shows that the distribution of Von-Mises stress and their position in experimental tests and failure of these structures is also very close, which provides validation to the experimental setup and the testing of beams.