Auxetic materials are of great engineering interest not only because of their fascinating negative Poisson's ratio, but also due to the possibility to increase by design the toughness and indentation resistance. The general understanding of auxetic materials comes often from ordered or periodic structures, while auxetic materials used in applications are typically strongly disordered. Yet, the effect of disorder in auxetics has rarely been investigated. Here, we provide a systematic theoretical and experimental study of the effect of disorder on the mechanical properties of a paradigmatic two-dimensional auxetic lattice with a re-entrant hexagonal geometry. We show that disorder has a marginal effect on the Poisson's ratio until the point when the lattice topology becomes altered, and in all cases examined disorder preserves the auxetic characteristics. Depending on the direction of loading applied to these disordered auxetic lattices, either brittle or ductile failure is observed. It is found that brittle failure is associated with a disorder-dependent tensile strength, whereas in ductile failure disorder does not affect strength. Our work thus provides general guidelines to design and optimize elasticity and strength of disordered auxetic metamaterials.

Mechanics of disordered auxetic metamaterials / M. Hanifpour, C.F. Petersen, M.J. Alava, S. Zapperi. - In: THE EUROPEAN PHYSICAL JOURNAL. B, CONDENSED MATTER PHYSICS. - ISSN 1434-6028. - 91:11(2018), pp. 271.1-271.8. [10.1140/epjb/e2018-90073-1]

Mechanics of disordered auxetic metamaterials

S. Zapperi
2018

Abstract

Auxetic materials are of great engineering interest not only because of their fascinating negative Poisson's ratio, but also due to the possibility to increase by design the toughness and indentation resistance. The general understanding of auxetic materials comes often from ordered or periodic structures, while auxetic materials used in applications are typically strongly disordered. Yet, the effect of disorder in auxetics has rarely been investigated. Here, we provide a systematic theoretical and experimental study of the effect of disorder on the mechanical properties of a paradigmatic two-dimensional auxetic lattice with a re-entrant hexagonal geometry. We show that disorder has a marginal effect on the Poisson's ratio until the point when the lattice topology becomes altered, and in all cases examined disorder preserves the auxetic characteristics. Depending on the direction of loading applied to these disordered auxetic lattices, either brittle or ductile failure is observed. It is found that brittle failure is associated with a disorder-dependent tensile strength, whereas in ductile failure disorder does not affect strength. Our work thus provides general guidelines to design and optimize elasticity and strength of disordered auxetic metamaterials.
Poissons ratio; soft metamaterials; foam structures; propagation; networks
Settore FIS/03 - Fisica della Materia
Article (author)
File in questo prodotto:
File Dimensione Formato  
paper_epjb.pdf

accesso aperto

Tipologia: Post-print, accepted manuscript ecc. (versione accettata dall'editore)
Dimensione 1.7 MB
Formato Adobe PDF
1.7 MB Adobe PDF Visualizza/Apri
Hanifpour2018_Article_MechanicsOfDisorderedAuxeticMe.pdf

accesso riservato

Tipologia: Publisher's version/PDF
Dimensione 1.25 MB
Formato Adobe PDF
1.25 MB Adobe PDF   Visualizza/Apri   Richiedi una copia
Pubblicazioni consigliate

Caricamento pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/614953
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 14
  • ???jsp.display-item.citation.isi??? 17
social impact