3D printing of metamaterials for structural applications

Additive manufacturing, or 3D metal printing, allows to build ultralight and resistant structures with geometries that are impossible to achieve using conventional machining and processing techniques, including complex structures named “lattice”. These are three-dimensional constructions, topologically ordered, formed by the periodic repetition of unit cells, which, in turn, are classified according to the dimension and connectivity of the microbeams that compose them, which are connected in the so-called “nodes”. The set of unit cells, which constitutes the “lattice” structure, behaves like a “metamaterial”.

Lattice structures are finding applications mainly in biomedicine, where they allow the manufacture of implants with elastic modules similar to the bone, and in aeronautics, where their high specific mechanical resistance is highly appreciated.

By altering the topology (or connectivity) of these structures, as well as the geometry (unit cell size and thickness of the microbeams), it is possible to modify their physical behavior, sometimes achieving physical properties that are impossible to achieve in the same massive metallic materials. Thus, it is possible to obtain extraordinary acoustic, dielectric and mechanical properties. 3D printing techniques are particularly suited to designing metamaterials with unique properties due to the great design flexibility they provide.

Within the project MAT4.0, researchers of IMDEA Materials are trying to further amplify the range of properties that can be obtained in the aforementioned metamaterials through the modulation of their microstructure by combination an optimization of 3D printing parameters and subsequent heat treatments. Preliminary results of this project show that the mechanical behavior of manufactured lattice structures can be greatly altered by coupling their microstructure and mesostructure.