Temat: auxetics - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Modelling of the static and dynamic properties of tho-type silicates
Autorzy:: Cauchi, R.
Grima, J. N.
Tematy:: auxetics
zeolites
thomsonite
molecular dynamics; Pokaż więcej
Data publikacji:: 2014
Powiązania:: https://bibliotekanauki.pl/articles/1954447.pdf Link otwiera się w nowym oknie
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2014, 18, 1; 5-65
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Opis:: Auxetic materials are materials exhibiting a negative Poisson’s ratio in one of their planes. This phenomenon has been studied in various materials. Zeolites are crystalline substances whose structure is characterised by the framework of linked tetrahedra, each consisting of four oxygen atoms surrounding a cation. The resulting interstitial spaces make them efficient for use as adsorbents and molecular sieves, and many studies have been focused on this aspect. Some of these zeolites may exhibit auxeticity at least in one of their planes. THO (and similar systems, such as NAT and EDI) together with the all-silica equivalent of these have been studied extensively via static simulations for their negative Poisson’s ratio in the (001) plane. In this paper a study of the all-silica equivalent of THO has been carried out via both static and dynamic simulations using the same force-field, where the system was subjected to stress along the x direction. The hypothesised semi-rigid mechanism of deformation, proposed by Grima et al. was then projected over this framework. The results obtained confirmed auxeticity along this plane by means of the COMPASS force-field, in both static and dynamic studies and compared well with the proposed mechanism of semi-rigid rotating polygons. It also showed that as the Young’s modulus of this mechanism increases other mechanisms of deformation increase in importance.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Auxetics as entropy filters - possible application
Autorzy:: Wojciechowski, K. W.
Kempinski, W.
Tematy:: superfluidity
entropy filters
auxetics
3He isotope; Pokaż więcej
Data publikacji:: 2016
Powiązania:: https://bibliotekanauki.pl/articles/1938609.pdf Link otwiera się w nowym oknie
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2016, 20, 3; 271-272
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Opis:: In this note a sketch of the idea of applying auxetics to separation of 3He from a mixture of 4He and 3He by using auxetic entropy filters is presented.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Mechanical and structural properties of poly(phenylethylene) systems: a preliminary study
Autorzy:: Farrugia, Zachary
Grima, Joseph N.
Tematy:: auxetics
negative Poisson ratio
organic networked polymers; Pokaż więcej
Data publikacji:: 2019
Powiązania:: https://bibliotekanauki.pl/articles/1955222.pdf Link otwiera się w nowym oknie
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2019, 23, 3; 269-301
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Opis:: The structural and mechanical properties of various types of poly(phenylacetylene) crystalline networked polymers which stack in the third direction in a graphite-like manner have been the subject of extensive research over the past few years. These studies have suggested that depending on the particular manner of substitution of the phenyls, it is possible to achieve some very interesting mechanical properties, which include, in some cases, negative Poisson's ratio (NPR) andór negative linear compressibility (NLC). The current study investigated how alternatives to these systems can be designed, and specifically tailor-made to exhibit desirable anomalous properties, such as NPR and NLC, through the replacement of the acetylene chains with ethylene chains, so as to produce the poly(phenylethylene) equivalents. Using force field-based simulations, via the use of the polymer consistent force-field (PCFF) it was noted that, to a first approximation, these systems mirror some of the analogous properties exhibited by their poly(phenylacetylene) counterparts. In particular, poly(phenylethylene) systems built from 1234- and 1245-substituted phenyls exhibited negative Poisson's ratios, with the latter also exhibiting negative linear compressibility. This anomalous behaviour, mirrors, to some extent, that exhibited by their poly(phenylacetylene) counterparts, albeit some differences were noted, such as a reduction in the degrees of auxeticity. It was also noted that the poly(phenylethylene) systems modelled here tend to stack in the third direction, in a different manner than their poly(phenylacetylene) analogues, which difference is likely to be the factor for such reduction in auxeticity.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Numerical modeling of auxetics in structure strength
Autorzy:: Stanisławek, S.
Morka, A.
Niezgoda, T.
Tematy:: computational mechanics
auxetics
negative Poisson's ratio
material engineering; Pokaż więcej
Data publikacji:: 2010
Powiązania:: https://bibliotekanauki.pl/articles/241667.pdf Link otwiera się w nowym oknie
Źródło:: Journal of KONES; 2010, 17, 4; 459-462
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Opis:: The paper deals with computer simulations of mechanical behaviour of a no-void ideal auxetic isotropic material. Current literature offers wide range of models which resemble the manufactured or natural structures. However, it does not answer the question how a change into auxetic no-void state would affect the continuum effective mechanical properties. Auxetic with the Poisson ratio -0.3 has been compared through typical tests to a classic steel elastic material. Most of the engineering software cannot precede Poisson ratio helow zero. Therefore a unique technique was applied using equation of state to overcome this obstacle. All simulations have been done in elastic regime. For the tensile compression tests a 10 mm edge cube was modelled, the bending test used a 5x5x250 mm bar. The loading for initial tests was realized as a kinematic displacement of particular nodes. For bar bending a force was applied in the middle of the beam. The finite element method has been used with explicit time integration algorithm implemented in commercial software with one integration point brick elements. Specific properties have been observed for each test, for tensile test auxetic showed higher strength while for compression material was weaker. Logically the bending test showed no clear influence of negative Poisson to material strength. Further simulations as a shear or impact tests are planned.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Negative Poissons ratio and percolating structures
Autorzy:: Wojciechowski, K. W.
Novikov, V. V.
Tematy:: auxetics
polymers
elastic properties
percolation
percolating structures
Poisson ratio
renormalization group; Pokaż więcej
Data publikacji:: 2001
Powiązania:: https://bibliotekanauki.pl/articles/1964096.pdf Link otwiera się w nowym oknie
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2001, 5, 1; 5-11
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Opis:: Elastic properties of non-uniform, two-component systems are studied in frames of a model of percolation on a simple cubic lattice. It is shown that as the ratio of the bulk moduli of the components tends to zero, kappa =K/sub s//K/sub h/ to 0 (where s,h denote the softer and harder phase, respectively), the Poisson's ratio of the system tends to 0.2 at the percolation threshold of the harder phase, no matter what the values are of the Poisson's ratios of the components. A qualitatively new, collective mechanism leading to negative Poisson's ratio is suggested.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Mechanical properties of 2D flexyne and reflexyne polyphenylacetylene networks: a comparative computer studies with various force-fields
Autorzy:: Trapani, L.
Gatt, R.
Mizzi, L.
Grima, J. N.
Tematy:: 2D flexyne polyphenylacetylene networks
2D reflexyne polyphenylacetylene networks
auxetics
molecular simulations; Pokaż więcej
Data publikacji:: 2015
Powiązania:: https://bibliotekanauki.pl/articles/1938614.pdf Link otwiera się w nowym oknie
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2015, 19, 3; 237-296
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Opis:: Auxetic materials exhibit the very unusual property of becoming wider when stretched and narrower when compressed, – they have a negative Poisson’s ratio. This unusual behaviour is the source of many desired effects in the materials’ properties and it is therefore, no wonder that auxetics are described as being superior to conventional materials in many practical applications. Here we make use of force-field based molecular modelling simulations in order to investigate the mechanical properties of polypehyleacetylene systems known as (n, m)-flexyne and (n, m)-reflexyne in an attempt to extend the existing knowledge there is regarding these systems. These systems have already attracted considerable consideration since negative on-axis Poisson’s ratios have been discovered for the reflexynes. We first developed a methodology for the modelling and property determination of flexyne and reflexyne network systems which we validated against existing published data. Then, extended the study to prove the simulated results were independent of the modelling methodology or the force-field used. In particular, we showed that on-axis auxeticity in the reflexynes is a force-field independent property, i.e. a property which is not an artefact of the simulations but a property which is likely to be present in the real materials if these were to be synthesised. We also studied and reported the shear behaviour of these systems were we show that the flexynes and reflexynes have very low shear moduli, a property which regrettably limits the prospects of these systems in many practical applications. Finally we examine the in-plane off-axis mechanical properties of the systems and we report that in general, these mechanical properties are highly dependent on the direction of loading. We also find that the auxeticity exhibited by the reflexynes on-axis is lost when these systems are loaded off axis since the Poisson’s ratios becomes positive very rapidly as the structure is stretched slightly off-axis (e.g. 15deg off-axis). This is once again of great practical significance as it highlights another major limitation of these systems in their use as auxetics.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Computational modelling of vibrations transmission loss of auxetic lattice structure
Autorzy:: Idczak, E.
Stręk, T.
Tematy:: auxetics
negative Poisson's ratio
dynamic analysis
VTL factor
auksetyki
ujemny współczynnik Poissona
analiza dynamiczna
współczynnik utraty przewodzenia drgań; Pokaż więcej
Data publikacji:: 2016
Powiązania:: https://bibliotekanauki.pl/articles/127808.pdf Link otwiera się w nowym oknie
Źródło:: Vibrations in Physical Systems; 2016, 27; 123-128
0860-6897
Pojawia się w:: Vibrations in Physical Systems
Opis:: In this article dynamical properties of auxetic lattice structures will be analysed. Auxetic structures are materials, which have negative Poisson’s ratio and some of these have got specific dynamic properties. Their dynamic behaviour in the frequency domain will be also shown in this article. The possibility of isolation of auxetics will show the factor VTL – Vibration Transmission Loss.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Blast resistance of sandwich plate with auxetic anti-tetrachiral core
Autorzy:: Michalski, Jakub
Strek, Tomasz
Tematy:: auxetics
sandwich plate
blast resistance
explicit dynamics
finite element method
auksetyk
płyta warstwowa
odporność na wybuch
metoda elementów skończonych; Pokaż więcej
Data publikacji:: 2020
Powiązania:: https://bibliotekanauki.pl/articles/2146596.pdf Link otwiera się w nowym oknie
Źródło:: Vibrations in Physical Systems; 2020, 31, 3; art. no. 2020317
0860-6897
Pojawia się w:: Vibrations in Physical Systems
Opis:: Auxetic structures exhibit unusual behavior not only when subjected to static loads but also in case of dynamic events. However, their response to transient loads still requires further research. In this article, the blast resistance of auxetic and non-auxetic sandwich plates was compared using the finite element method. The first stage of works, that consisted of the analyses of plates with homogenized core with different values of Poisson’s ratio subjected to blast load, proved that auxetic core may increase the resistance to this kind of load. In the next step, two sandwich plates were compared - one with auxetic anti-tetrachiral core and one with a non-auxetic hexagonal honeycomb core. Obtained results indicate that auxetic plate has superior blast resistance when compared with the regular sandwich panel.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Dynamic analysis of optimized two-phase auxetic structure
Autorzy:: Idczak, E.
Stręk, T.
Tematy:: negative Poisson's ratio
auxetics
eigenfrequency
topology optimization
dynamic analysis
ujemny współczynnik Poissona
auksetyki
częstotliwość drgań własnych
optymalizacja topologiczna
analiza dynamiczna; Pokaż więcej
Data publikacji:: 2017
Powiązania:: https://bibliotekanauki.pl/articles/127856.pdf Link otwiera się w nowym oknie
Źródło:: Vibrations in Physical Systems; 2017, 28; 1-12
0860-6897
Pojawia się w:: Vibrations in Physical Systems
Opis:: This paper presents a dynamic analysis of earlier optimized auxetic structure. This optimization based on the distribution of two materials in such way to obtain a minimal value of Poisson’s ratio (PR), which indicates the auxetic properties. The initial optimized shape was so-called star structure, which if is made from one material has the PR close to 0.188. After optimization with the goal function of PR-minimization, the obtained value was equal to -9.5043. Then the eigenfrequencies for the optimized structure were investigated. The calculations were carried out by means of Finite Element Method (FEM). For optimization of the value of Poisson’s ratio was used algorithm MMA (Method of Moving Asymptotes). The computing of single material properties (PR, Young’s modulus, density) for the whole shape was made by means of SIMP method (Solid Isotropic Method with Penalization).
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Materiały auksetyczne – struktury, potencjalne zastosowanie
Auxetic materials – structures, potential application
Autorzy:: Masłowska-Lipowicz, Iwona
Wyrębska, Łucja
Szałek, Beata
Olszewski, Piotr
Gajewski, Robert
Tematy:: materiały auksetyczne
włókno auksetyczne
ujemny współczynnik Poisson’a
zastosowanie materiałów auksetycznych
auxetic materials
auxetics
auxetic fibre
negative Poisson's ratio
use of auxetic materials; Pokaż więcej
Data publikacji:: 2020
Powiązania:: https://bibliotekanauki.pl/articles/1818680.pdf Link otwiera się w nowym oknie
Źródło:: Technologia i Jakość Wyrobów; 2020, 65; 116--128
2299-7989
Pojawia się w:: Technologia i Jakość Wyrobów
Opis:: Dokonano przeglądu literatury pod kątem badań materiałów auksetycznych, które posiadają ujemny współczynnik Poisson’a (NPR) charakteryzujący odpowiedź materiału na naprężenie jednoosiowe. Struktury i materiały auksetyczne zachowują się sprzecznie z intuicją, tzn. przy jednoosiowym rozciąganiu, rozszerzają się poprzecznie, co wynika z ich skomplikowanych struktur geometrycznych. Opisano reprezentatywne modele strukturalne (re-entrant, struktury składające się z tzw. sztywnych lub półsztywnych obracających się jednostek , struktury chiralne, przędze auksetyczne i struktury włókienkowo-zgrubieniowe) oraz zastosowanie materiałów auksetycznych wynikające z ich właściwości. Właściwości materiałów auksetycznych, np. synklastyczna krzywizna zginania, zmienna przepuszczalność, zwiększona odporność na wgniecenia, wysoka odporność na pękanie oraz tłumienie i pochłanianie dźwięku stwarzają szerokie możliwości ich zastosowania, m.in. w materiałach biomedycznych, materiałach amortyzujących, urządzeniach do pozyskiwania energii, wyposażeniu sportowym, filtrach, robotyce, tekstyliach czy materiałach stosowanych w przemyśle lotniczym oraz budownictwie.
The literature was reviewed in terms of research on auxetic materials with a negative Poisson's ratio (NPR) characterizing the material's response to uniaxial stress. Auxetic structures and materials behave counter-intuitively, i.e. when stretched uniaxially, they expand laterally due to their complex geometric structures. Representative structural models are described (re-entrant, structures consisting of so-called rigid or semi-rigid rotating units, chiral structures, auxetic yarns and fibril - noudle structures) and the use of auxetic materials resulting from their properties. Properties of auxetic materials, e.g. synclastic bending curvature, variable permeability, high shear stiffness, increased resistance to indentation, high resistance to cracking and sound attenuation and absorption create a wide range of applications, including in biomedical materials, shock-absorbing materials, energy generation devices, sports equipment, filters, robotics, textiles or materials used in the aerospace industry and construction.
Dostawca treści:: Biblioteka Nauki

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