A simple way to make elastically-isotropic closed-cell plate-lattices: Effective properties of Ti-6Al-4V cubic+octet foam material

Abstract

Architected metamaterials with optimal mechanical isotropy have been a long quest in the lightweight materials industry. Plate-lattices are likely to be the most promising candidates to fulfill this request. Nonetheless, unlocking full application potential of plate-lattices requires addressing many inherent drawbacks of existing additive manufacturing techniques. Hereby an alternative route is proposed to fabricate a particular plate-lattice, i.e., cubic+octet foam, based on snap-fit design concept. The proposed protocol allows for high-precision manufacturing, and is capable of scalable production with ease and offers great versatility in base material selection. Mechanical properties of plate-lattices created in this way are first numerically assessed, showing optimal stiffness and strength close to theoretical bounds for isotropic porous media, and a high degree of mechanical isotropy. Compression experiments are further conducted to exam the actual behavior of Ti-6Al-4V foam representatives, and compared with explicit simulations featuring fracture and interfacial-debonding processes, such that the dependency of foam’s performance on the degree of joint robustness is numerically quantified. Speaking of the uniqueness of this fabrication strategy, it allows for easy implementation of structural hierarchy and hybrid design; it also provides a simple way to utilize lab-scale advanced materials that are demanding even impractical to realize scalable production.