Investigation of the relationship between flexural modulus of elasticity and functionally graded porous structures manufactured by AM

There is an increased interest to produce open porous metallic lattice structures with regular unit cell architectures by additive manufacturing processes, which were impossible or difficult to manufacture using conventional techniques. In this study, the physical and mechanical properties of functionally graded porous structures were investigated to establish a relationship between porosity and elastic modulus of the cellular structure. Three different unit cell structures of diamond, cubic, and octahedroid and three different strut thicknesses of 0.3 mm, 0.5 mm, and 0.7 mm were designed for the experimental and theoretical study. A functionally graded porous structure was formed by using three different unit cell sizes (1.8 mm, 2 mm, and 2.2 mm) in each model. The specimens were produced by laser powder bed fusion (L-PBF) using Ti-6Al-4V powder and subjected to a three-point bending test after heat treatment. A mathematical model was created to determine the modulus of elasticity of the porous structures. Experimental results were compared with the theoretical calculations. As a result of this study, a correlation was established between the flexural modulus of elasticity and the porosity of the three different cell structures.