Intrinsically Polar Elastic Metamaterials. Issue 26 (3rd May 2017)

• Record Type: Journal Article
• Authors: Bilal, Osama R.; Süsstrunk, Roman; Daraio, Chiara; Huber, Sebastian D.
• Is Part Of: Advanced materials. Volume 29:Issue 26(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-05-03
• Subjects: mechanical metamaterials -- topological insulators -- anisotrpoic elasticity -- zero‐frequency phonons -- Weyl lines; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201700540
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract : In many applications, one needs to combine materials with varying properties to achieve certain functionalities. For example, the inner layer of a helmet should be soft for cushioning while the outer shell should be rigid to provide protection. Over time, these combined materials either separate or wear and tear, risking the exposure of an undesired material property. This work presents a design principle for a material that gains unique properties from its 3D microstructure, consisting of repeating basic building blocks, rather than its material composition. The 3D printed specimens show, at two of its opposing faces along the same axis, different stiffness (i.e., soft on one face and hard on the other). The realized material is protected by design (i.e., topology) against cuts and tears: No matter how material is removed, either layer by layer, or in arbitrary cuts through the repeating building blocks, two opposing faces remain largely different in their mechanical response. Abstract : Topologically protected metamaterials present strongly anisotropic elastic properties, which are immune to damage and fracture. A 3D material with strongly face‐dependent surface elasticity is fabricated using additive manufacturing. Topological band theory is used for its design, and experiments are performed to validate the topological features. Experimental measurements also reveal a Weyl nodal line in the bulk phonon spectrum of the metamaterial.