Mechanical Response of Octahedral and Octet-Truss Lattice Structures Fabricated Using the CLIP Technology

Abstract

In the rapidly growing field of additive manufacturing (AM), the focus in recent years has shifted from prototyping to manufacturing fully functional, ultralight, ultrastiff end-use parts. This research investigates the mechanical behavior of octahedral- and octet-truss lattice structured polyacrylate fabricated using Continuous Liquid Interface Production (CLIP) technology based on 3D printing and additive manufacturing processes. Continuous Liquid Interface Production (CLIP) is a breakthrough technology that grows parts instead of printing them layer by layer. CLIP is a chemical process that carefully balances UV light and oxygen to eliminate additional mechanical steps for part delamination and resin refill. UV light triggers photopolymerization and oxygen inhibits it. By carefully balancing the interaction of light and oxygen, CLIP grows objects from a pool of resin. Lattice structures such as the octahedral- and octet-truss lattice have recently attracted a lot of attention since they are often structurally more efficient than foams of a similar density made from the same material, and the ease with which these structures can now be produced using 3D printing and additive manufacturing. This research investigates the mechanical response under compression of octahedral- and octet-truss lattice structured polyacrylate fabricated using CLIP technology. It was found that the elastic modulus and strength of the octahedral-truss structured materials are proportional to each other over a relative density range of 0.07 to 0.35. Finally, even though the octet-truss lattice structure is a stretch-dominated unit cell structure, it was found to have a lower stiffness and strength as compared to an octahedral-truss structure of the same relative density. This can be attributed to the smaller diameter and therefore larger l/d of individual struts.