Inverted and Programmable Poynting Effects in Metamaterials

Aref Ghorbani*, David Dykstra, Corentin Coulais, Daniel Bonn, Erik van der Linden, Mehdi Habibi*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

1 Citation (Scopus)

Abstract

The Poynting effect generically manifests itself as the extension of the material in the direction perpendicular to an applied shear deformation (torsion) and is a material parameter hard to design. Unlike isotropic solids, in designed structures, peculiar couplings between shear and normal deformations can be achieved and exploited for practical applications. Here, a metamaterial is engineered that can be programmed to contract or extend under torsion and undergo nonlinear twist under compression. First, it is shown that the system exhibits a novel type of inverted Poynting effect, where axial compression induces a nonlinear torsion. Then the Poynting modulus of the structure is programmed from initial negative values to zero and positive values via a pre-compression applied prior to torsion. The work opens avenues for programming nonlinear elastic moduli of materials and tuning the couplings between shear and normal responses by rational design. Obtaining inverted and programmable Poynting effects in metamaterials inspires diverse applications from designing machine materials, soft robots, and actuators to engineering biological tissues, implants, and prosthetic devices functioning under compression and torsion.

Original languageEnglish
Article number2102279
JournalAdvanced Science
Volume8
Issue number20
Early online date17 Aug 2021
DOIs
Publication statusPublished - 2021

Keywords

  • mechanical metamaterials
  • normal and shear moduli
  • normal force
  • Poynting effect
  • torsion

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