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Negative Poisson's ratio

qing.peng's picture

The normal-auxeticity mechanical phase transition in graphene

When a solid object is stretched, in general, it shrinks transversely. However, the abnormal ones are auxetic, which exhibit lateral expansion, or negative Poisson ratio. While graphene is a paradigm 2D material, surprisingly, graphene converts from normal to auxetic at certain strains. Here, we show via molecular dynamics simulations that the normal-auxeticity mechanical phase transition only occurs in uniaxial tension along the armchair direction or the nearest neighbor direction. Such a characteristic persists at temperatures up to 2400 K.

Giorgio Carta's picture

Design of a porous material with isotropic negative Poisson's ratio

This paper proposes the design of a two-dimensional porous solid with omnidirectional negative Poisson's ratio. The hexagonal periodic distribution of the pores makes the effective behavior isotropic. Both experimental tests and numerical simulations have been performed to determine the effective properties of the porous solid. A parametric study on the effect of the geometrical microstructural parameters is also presented. This auxetic structure is easy to fabricate and can be very useful in several engineering applications.

 

Harold S. Park's picture

Negative Poisson's Ratio in Single-Layer Graphene Ribbons

The Poisson's ratio characterizes the resultant strain in the lateral direction for a material under longitudinal deformation.  Though negative Poisson's ratios (NPR) are theoretically possible within continuum elasticity, they are most frequently observed in engineered materials and structures, as they are not intrinsic to many materials.  In this work, we report NPR in single-layer graphene ribbons, which results from the compressive edge stress induced warping of the edges.

tchuhong's picture

Positions for Research Assistant, Research Associate, PhD student or Postdoctoral Fellow at the Hong Kong Polytechnic University

We are looking for candidates who have strong background in mechanics to help us modelling and simulating of 2D and 3D nonconventional textile structures with negative Poisson’s ratio (auxetic textiles). The positions can be Research Assistant, Research Associate, PhD student or Postdoctoral Fellow depending on applicant’s previous experience.

 

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