Cancellation of Auxetic Properties in F.C.C. Hard Sphere Crystals by Hybrid Layer-Channel Nanoinclusions Filled by Hard Spheres of Another Diameter.

Jakub W Narojczyk,Jerzy Smardzewski,Krzysztof W Wojciechowski,Attila R Imre,Joseph N Grima,Mikołaj Bilski

doi:10.3390/ma14113008

Abstract

The elastic properties of f.c.c. hard sphere crystals with periodic arrays of nanoinclusions filled by hard spheres of another diameter are the subject of this paper. It has been shown that a simple modification of the model structure is sufficient to cause very significant changes in its elastic properties. The use of inclusions in the form of joined (mutually orthogonal) layers and channels showed that the resulting tetragonal system exhibited a complete lack of auxetic properties when the inclusion spheres reached sufficiently large diameter. Moreover, it was very surprising that this hybrid inclusion, which can completely eliminate auxeticity, was composed of components that, alone, in these conditions, enhanced the auxeticity either slightly (layer) or strongly (channel). The study was performed with computer simulations using the Monte Carlo method in the isothermal-isobaric () ensemble with a variable box shape.

Highlights

Auxetic materials [1] play an important role in designing and developing modern metamaterials
Apart from the comparison to previous models, an analysis of different pressure values, as a second parameter impacting the elastic properties of the sphere system with hybrid inclusions, has been provided
Crystals of hard spheres may be significantly altered by small modifications of the crystalline structure

Summary

Introduction

Auxetic materials [1] play an important role in designing and developing modern metamaterials. Novel structures [26,27,28,29,30,31,32,33,34], nanostructures [35,36], and models [37,38,39,40,41,42,43,44], real materials (e.g., polymers [45,46], composites [47], or foams [48,49]), and metamaterials [50,51] with auxetic properties have been designed and reported These advances in real metamaterials would not have been possible without more basic research [52,53,54], analysis [55,56,57,58,59], and optimization [60,61] of auxetic models on various levels. This effort is motivated by the extraordinary, counterintuitive elastic properties and potential applications of auxetics [62,63,64,65,66,67,68]

Methods

Results

Conclusion