Designing programmable materials from metals
Achievements in additive manufacturing enable structuring materials on a micro- and meso-scale. Being able to structure materials on this level allows us to implement novel functionality and to determine the macroscopic behavior of the continuum. Often referred to as mechanical metamaterials, they exhibit fundamentally different properties than the underlying structural material.
Mechanical programmable materials use a stimuli-excited change in the structure to switch between more than one property in the same material. This functionality can be described as a system’s behavior (sensing, processing and acting). It allows to use mechanically logical elements (e.g. conditional element, materials memory, processing functions), which are implemented as mechanical mechanisms (e.g. contact, bistability) into materials.
To enable a straight forward process to design and implement programmable materials the fundamental building blocks need to be identified. Therefore a classification of different structures will be presented. In literature existing unit cells and mechanisms of metamaterials are classified by e.g. geometry, mechanism, used material or mechanical boundary conditions (such as critical reversible strain) and others.
The classified metamaterials help to identify limitations, e.g. mechanical boundary conditions that allow only specific classes of base materials to be used.
Challenges in the development of metallic programmable materials will be discussed, e.g. aspects of reliability during cyclic loading and the effect on the lifetime behavior. Possible designs to implement metal programmable materials based on simulations will be presented.