Mechanical Behavior of Octahedral and Octet Structures Produced From CLIP Technology

This research concerns the production of mechanical metamaterials by a new means of additive manufacturing (AM). Mechanical metamaterials are man-made materials in which the mechanical properties are defined mainly by their structures rather than the properties of each material component. They are typically cellular lattice structures consisting of various arrangements of interconnected webs and struts. These metamaterials have a wide range of applications, but due to a recent breakthrough technology in the field of AM developed by Carbon, called Continuous Liquid Interface Production (CLIP), they can now be produced with ease at substantially higher speeds on a large scale. Using the CLIP process, Adidas is now utilizing these metamaterials in the midsoles of their new athletic shoes. More information about the mechanical response of parts produced by CLIP was needed to assess their relevance in this application. The goal of this research was to quantitatively determine the isotropy of octahedral and octet lattice structures produced from CLIP technology. Carbon claims that CLIP technology, unlike most other AM processes, produces parts that are isotropic. This means parts will have the same mechanical properties regardless of the direction of applied load. This claim has yet to be proven on lattice structures like the octahedral and octet structures. Those particular lattice structures are popular in the field of mechanical metamaterials because they are more structurally efficient than foams that are made of the same material with similar densities. The degree of isotropy of samples was measured by comparing values of various mechanical properties. These properties include Young’s modulus, a common measure of elasticity, and peak stress, a common measure of strength. Results indicated relatively isotropic behavior because mechanical properties varied based on the axis of compression by 6.5%, on average. The physical responses and failure mechanisms were also consistent.