title: Hierarchical auxetic mechanical metamaterials.
abstract: Auxetic mechanical metamaterials are engineered systems that exhibit the unusual macroscopic property of a negative Poisson's ratio due to sub-unit structure rather than chemical composition. Although their unique behaviour makes them superior to conventional materials in many practical applications, they are limited in availability. Here, we propose a new class of hierarchical auxetics based on the rotating rigid units mechanism. These systems retain the enhanced properties from having a negative Poisson's ratio with the added benefits of being a hierarchical system. Using simulations on typical hierarchical multi-level rotating squares, we show that, through design, one can control the extent of auxeticity, degree of aperture and size of the different pores in the system. This makes the system more versatile than similar non-hierarchical ones, making them promising candidates for industrial and biomedical applications, such as stents and skin grafts.
authors: Metamaterials Unit, Faculty of Science, University of Malta, Msida, MSD 2080, Malta.
authors: Ruben
authors: R
authors: Gatt
authors: Metamaterials Unit, Faculty of Science, University of Malta, Msida, MSD 2080, Malta.
authors: Luke
authors: L
authors: Mizzi
authors: Metamaterials Unit, Faculty of Science, University of Malta, Msida, MSD 2080, Malta.
authors: Joseph I
authors: JI
authors: Azzopardi
authors: Metamaterials Unit, Faculty of Science, University of Malta, Msida, MSD 2080, Malta.
authors: Keith M
authors: KM
authors: Azzopardi
authors: Metamaterials Unit, Faculty of Science, University of Malta, Msida, MSD 2080, Malta.
authors: Daphne
authors: D
authors: Attard
authors: 1] Metamaterials Unit, Faculty of Science, University of Malta, Msida, MSD 2080, Malta [2] Department of Anatomy, Faculty of Medicine and Surgery, University of Malta, Msida, MSD 2080, Malta.
authors: Aaron
authors: A
authors: Casha
authors: Burns Unit, Mater Dei Hospital, Msida, MSD 2090, Malta.
authors: Joseph
authors: J
authors: Briffa
authors: 1] Metamaterials Unit, Faculty of Science, University of Malta, Msida, MSD 2080, Malta [2] Department of Chemistry, Faculty of Science, University of Malta, Msida, MSD 2080, Malta.
authors: Joseph N
authors: JN
authors: Grima
mesh_terms: D008962:Models, Theoretical