Keith M. Azzopardi

Keith M. Azzopardi
University of Malta · Metamaterials Unit

PhD

About

12
Publications
2,366
Reads
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680
Citations
Citations since 2017
0 Research Items
573 Citations
2017201820192020202120222023020406080100120
2017201820192020202120222023020406080100120
2017201820192020202120222023020406080100120
2017201820192020202120222023020406080100120
Additional affiliations
November 2014 - present
Thought3D
Position
  • Managing Director
March 2013 - May 2015
University of Malta
Position
  • Research Officer

Publications

Publications (12)
Article
Perforated systems with quasi-disordered arrays of slits are found to exhibit auxetic characteristics almost as much as their traditional ordered "rotating-squares" counterparts. This provides a highly robust methodology for constructing auxetics that may be used for various practical applications such as skin grafting, where a high degree of preci...
Article
α‐cristobalite is a metastable polymorph of silica which has the remarkable property of exhibiting a negative Poisson's ratio (auxetic). In this study, the mechanical properties and deformation mechanisms of this system were investigated through a force‐field based approach. Besides simulations on the actual structure of α‐cristobalite, a number of...
Article
Auxetic metamaterials have generated a great deal of interest in recent years. In this letter, a novel approach which can be used to produce such auxetic metamaterials is presented. This method involves the introduction of patterned slit perforations within a sheet/block of material in order to create systems which resemble a large variety of auxet...
Article
The geometric perturbation of the cyclopropyl ring in [LAu(S)](n+) (S = cyclopropyl(methoxy)carbene) complexes has been recently proposed as an indirect experimental probe of the [LAu](n+) electron-donating power, but experimental data are available only for a phosphine ligand [Brooner et al., Chem. Commun., 2014, 50, 2420, L = P(t-Bu)2(o-biphenyl)...
Article
Tendons are visco-elastic structures that connect bones to muscles and perform the basic function of force transfer to and from the skeleton. They are essential for positioning as well as energy storing when involved in more abrupt movements such as jumping. Unfortunately, they are also prone to damage, and when injuries occur, they may have dilapi...
Article
Stishovite, a mineral which is estimated to be abundant in the Earth's mantle, exhibits negative Poisson's ratios for a range of loading directions at specific ambient pressure ranges. Here, we investigate the deformation mechanisms which lead to auxetic behaviour in the (001) plane in further detail, and show that the two-dimensional projection of...
Article
Full-text available
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 propo...
Article
Full-text available
Auxetics are materials which have a negative Poisson’s ratio, that is, upon uniaxial tensile loading, they also expand in a direction perpendicular to the applied force. Here, we analyze the elastic constants of stishovite, a high pressure silica polymorph which is known to be a significant constituent of the earth’s mantle, and show that it exhibi...
Article
Using experimental data, it is shown that the Poisson's ratios of standard (untreated) open cell polyurethane foam vary when loading in different loading directions, since foam is inherently asymmetric and anisotropic. The loading direction which is in plane orthogonal to the rise direction of the foam constantly exhibited the most negative Poisson...
Article
Chiral systems may exhibit auxetic behavior, i.e. they may have a negative Poisson’s ratio. This particular property has led to their being studied extensively by several authors. A Finite Elements Study is presented here, investigating the mode of connection between the nodes and ligaments in the anti-tetrachiral structure. The results show that t...
Article
Chiral systems are a class of structures, which may exhibit the anomalous property of a negative Poisson's ratio. Proposed by Wojciechowski and implemented later by Lakes, these structures have aroused interest due to their remarkable mechanical properties and numerous potential applications. In view of this, this paper investigates the on-axis mec...

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