Additive manufacturing and mechanical characterization of cellular materials with novel graded designs

Abstract

Cellular materials appear as a potential solution for the design of structures and components with tailored effective properties and performances. These are made from the tessellation of unit cells made from constituent elements in the form of struts or walls. While the designer can opt from a wide range of parameters to tune the effective properties (e.g., unit cell size, dimensions of the constituent elements, or even the topology of the pattern), a finer degree of tunability can be achieved when parameters are gradually modified. In this work, 15 functionally graded designs of the square cellular topology are investigated. These designs are additively manufactured using fused filament fabrication out of polylactic acid. Then, their effective mechanical properties were characterized by compressive tests. The experimental tests also brought some insights into the potential of controlling the deformed shapes by means of changing the grading parameters. These include inclination angle, thickness of the cell wall, and direction and symmetry of the grading. The results presented here showed that the consideration of grading in the design of cellular materials enables to increase the effective properties by roughly 9 times while keeping the same relative density. Finally, the failure modes of each design were visually analyzed by means of inspecting the deformation sequences during compression.