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1
Content available remote The f.c.c. Crystals of Hard Spheres with an Array of [001]-Nanochannel Inclusions Filled by the Simplest Hard Sphere Molecules
Narojczyk Jakub W.
Computational Methods in Science and Technology
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2023
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Vol. 29, No. 1-4
37--44
EN
In this work the systems composed of particles interacting with hard potential are investigated. These systems feature certain modifications to the crystal structure – selected particles are replaced with ones that differ slightly in their diameters. Such modifications, which can be thought of as “inclusions”, concern particles located in cylindrical nanochannels, oriented in [001] direction. In this study, for the first time, additional constrains have been imposed on the particles forming the inclusions. Namely, the replaced spheres have been randomly grouped into neighbouring pairs which were connected to form simple, di-atomic molecules. The results have been compared with previously investigated systems with similar inclusions but without the connections, i.e. filled only by spheres. The comparison of elastic properties between these systems is presented. It is shown that inclusions filled with dimers have different impact on the values of elastic compliances. It has been demonstrated that by introducing a small number of molecules made of spheres whose diameters differ from the rest of the particles forming the crystal, one is able to modify the hardness and shear resistance of the f.c.c. crystal without changing the Poisson’s ratio (with respect to the analogous system without additional constrains imposed on the inclusion particles).
2
Content available Testing the attenuation capabilities of ballistic shields made using 3D printing
Wierzbicka Karolina, Paszula Józef, Gieleta Roman, Komorek Zenon
Materiały Wysokoenergetyczne
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2022
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T. 14
58--75
EN
The paper describes a study of the blast wave energy absorption capabilities of sandwich ballistic shields. A comparative study of multilayer structures containing cores with different elementary cell shapes in their structure was performed. Energy-absorbing layers of different types of polymers were made. Tests of static and dynamic properties of the ballistic shield layers were carried out. The attenuation capabilities of these shields were determined by measuring the force acting on the base substrate of the shield.
PL
W pracy zaprojektowano i wykonano osłony balistyczne typu sandwich oraz przeprowadzono badania zdolności absorbowania energii fali podmuchowej. Przeprowadzono porównawcze badania struktur wielowarstwowych zawierających w swojej strukturze rdzenie o różnych kształtach komórek elementarnych. W badaniach przygotowano warstwy wykonane z różnych typów materiałów. Przeprowadzono badania właściwości statycznych i dynamicznych zaprojektowanych warstw osłon balistycznych. Zdolność tłumiącą wytypowanych osłon określano poprzez pomiar siły działającej na podstawę osłony.
3
Content available remote Rise of the Poisson’s Ratio in f.c.c. Hard Sphere Crystals with the Narrowest Orthogonal Nanochannels Filled by Hard Spheres of Another Diameter
Narojczyk Jakub W., Tretiakov Konstantin V., Wojciechowski Krzysztof W.
Computational Methods in Science and Technology
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2022
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Vol. 28, No. 2
61--75
EN
Auxetic materials, i.e. materials exhibiting negative Poisson’s ratio, stand to answer the demand for novel materials with unique and application-tailored properties. The vast range of potential applications motivates researchers to search for new materials with such properties, or to look for ways to modify the properties of existing materials. The study of systems with structural inclusions falls into the latter category. This work reports numerical investigations of elastic properties of hard sphere f.c.c. crystal. The investigations have been focused on Monte Carlo simulations of systems with arrays of inclusions filled by hard spheres of different diameter, resulting in binary systems, i.e. systems composed of two kinds of particles that differ only in size. Two different layouts of narrow nanoinclusions have been studied in the isobaricisothermal ensemble. It has been shown that even the narrowest inclusions can significantly alter elastic properties of hard particle crystal by eliminating auxetic properties while maintaining the effective cubic symmetry.
4
Content available remote Poisson’s Ratio of Yukawa Systems with Nanoinclusions: Nanochannel vs. Nanolayer
Tretiakov Konstantin V., Wojciechowski Krzysztof W., Narojczyk J. W., Pigłowski Paweł M.
Computational Methods in Science and Technology
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2022
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Vol. 28, No. 3
81--85
EN
The influence of periodically distributed inclusions on elastic properties of crystals in which particles interact through Yukawa potential is discussed briefly. The inclusions in the form of channels oriented along the [001]-direction and layers orthogonal to the [010]-direction are considered. Monte Carlo simulations have shown that, depending on the type of inclusion and the concentration of inclusion particles in Yukawa crystal, qualitative changes in elastic properties occur. In selected directions, one observes appearance of auxetic properties for systems with nanolayers and enhancement of auxeticity for systems with nanochannels.
5
Content available Numerical analysis of the lower limb prosthesis subjected to various load conditions
Kowalczyk Milena, Jopek Hubert
Vibrations in Physical Systems
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2020
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Vol. 31, nr 3
art. no. 2020309
EN
This article presents the simulation of a prosthetic socket with an auxetic structure under typical loading cases. The designed model of prosthetic socket is dedicated to patients who have undergone transfemoral amputation and consists of four elements, among which can be distinguished an inner lining, a shock absorbing element, component with a honeycomb re-entrant structure, which has a negative Poisson's ratio an outer shell. The prosthetic socket was analysed by means of the finite element method. The simulations were used to evaluate the strength of the design and to check whether it is possible to avoid a problem of changing the circumference of the patient's stump, thanks to the use of an auxetic structure in the socket.
6
Content available remote Smart Cellular Systems with Pressure Dependent Poisson’s Ratios
Attard D., Cauchi R., Gatt R., Grima-Cornish J. N., Grima J. N.
Computational Methods in Science and Technology
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2020
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Vol. 26, No. 2
37--45
EN
The Poisson’s ratio behaviour of cellular systems which change their internal features when subjected to pressure change to become a “re-entrant” or “non-re-entrant” honeycomb was investigated. It was shown, through finite elements simulations, that these changes in geometry permit the systems to exhibit a wide range of Poisson’s ratios, the magnitude and sign of which can be controlled through the external pressure. Auxetic behaviour was also shown to be obtainable at specific pressures with the right combination of design and materials.
7
Content available remote Auxetic polyurethane foams – method for determining a softening point
Lisiecki J.
Aviation Advances & Maintenance
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2017
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Vol. 40, Issue 2
5--21; 22--38
EN
The article described selected methods for determining a softening point of plastics (polymers). The way of determining a softening point of polyurethane foams was suggested. Moreover, the influence of annealing temperature of an auxetic polyurethane foam on its volume was presented.
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