Mechanics of disordered auxetic metamaterials

Research output: Contribution to journalArticleScientificpeer-review

Researchers

  • Maryam Hanifpour
  • Charlotte F. Petersen
  • Mikko Alava

  • Stefano Zapperi

Research units

  • University of Milan

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.

Details

Original languageEnglish
Article number271
Number of pages8
JournalEuropean Physical Journal B
Volume91
Issue number11
Publication statusPublished - 5 Nov 2018
MoE publication typeA1 Journal article-refereed

    Research areas

  • POISSONS RATIO, SOFT METAMATERIALS, FOAM STRUCTURES, PROPAGATION, NETWORKS

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