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1
Content available Materiały auksetyczne – struktury, potencjalne zastosowanie
Masłowska-Lipowicz Iwona, Wyrębska Łucja, Szałek Beata, Olszewski Piotr, Gajewski Robert
Technologia i Jakość Wyrobów
|
2020
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R. 65
116--128
PL
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.
EN
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.
2
Content available Vibration properties of auxetic beam
Matuszewska A., Stręk T.
Vibrations in Physical Systems
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2018
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Vol. 29
art. no. 2018031
EN
This study presents vibration analysis for a beam with an auxetic cross-section. In order to verify damping properties of auxetic materials, the numerical results were compared with classical H-beam which has basic geometry. The response of analyzed models was considered with taking into account the Rayleigh damping of the internal material structure. Performed calculations comprise deformation of the certain beam, selected points displacement and vibration transmission loss coefficient. The analysis was carried out by means of Finite Element Method using Comsol Multiphysics software.
3
Content available Forced response of plate with viscoelastic auxetic dampers
Stręk T.
Vibrations in Physical Systems
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2018
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Vol. 29
art. no. 2018003
EN
The example studies a forced response of plate with viscoelastic auxetic damper located at the free end of the plate. Damping elements consist of the cover layer and layer of viscoelastic material with positive or negative Poisson's ratio. Viscoelastic materials are often used for reduction of vibration (seismic or wind induced vibrations in building structures or other structures). The common feature is that the frequency of the forced vibrations is low. Calculations are made using finite element method with Comsol Multiphysics software.
4
Content available Experimental research on influence of gas impact on thermal and mechanical properties of auxetic material covered with titanium silicide coating
Miedzińska D., Gieleta R., Małek E., Zasada D., Stankiewicz M., Marszałek K.
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2018
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Vol. 66, nr 2
165--172
EN
The aim of the presented work was to study the auxetic textiles covered with titanium silicide coating. The research was carried out to develop the material structure, which will be used for protective clothing, e.g. for firemen. The new material should be characterized by increased heat resistance coupled with protection against gas pressure impact caused e.g. by gas installation damage. In the paper, an assessment of the change in heat resistance properties of a Ti-Si coated auxetic textile loaded with gas pressure impulse was carried out.
5
Content available Comparative study of bending stiffness of sandwich plates with cellular cores
Janus-Michalska M., Jasińska D.
Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika
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2017
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z. 89 [295], nr 2
63--70
EN
This paper presents numerical simulation of a sandwich plate bending. Two types of plates are considered: with a cellular honeycomb core and with the cellular auxetic core. Finite element method (FEM) calculations are performed by means of ABAQUS system for determination of plates bending stiffness. Three methods are presented. The first one, numerically expensive, is based on detailed modelling of cellular core structure, the second applies laminated plate theory with an equivalent core stiffness, the third applies theory of composite beams. The results show limitations of applicability of abovementioned models to stiffness modelling. The influence of core lattice geometry parameters on plate stiffness is studied.
PL
W artykule przedstawiono numeryczne symulacje testów zginania płyt sandwichowych wypełnionych materiałami komórkowymi o strukturze plastra miodu oraz strukturze auksetycznej. Celem wyznaczenia sztywności giętnej płyt wykonano obliczenia numeryczne w systemie ABAQUS metodą elementów skończonych. Prezentowane są dwie metody. Pierwsza kosztowna numerycznie polega na szczegółowym modelowaniu struktury komórkowej, druga stosuje teorię laminatów, trzecia teorię belek zespolonych. Wyniki wskazują na możliwość modelowania sztywności giętnej płyty. Przeanalizowano wpływ parametrów geometrycznych, a w szczególności auksetyczności struktury.
6
Content available Dynamic analysis of optimized two-phase auxetic structure
Idczak E., Stręk T.
Vibrations in Physical Systems
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2017
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Vol. 28
art. no. 2017003
EN
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).
7
Content available Computational modelling of vibrations transmission loss of auxetic lattice structure
Idczak E., Stręk T.
Vibrations in Physical Systems
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2016
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Vol. 27
123--128
EN
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.
8
Content available Core-shell modelling of auxetic inorganic materials
Zammit V., Gatt R., Attard D., Grima J. N.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2014
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Vol. 18, No 2
137--165
EN
This paper investigates the suitability of the General Utility Latti ce Program ( GULP ) for studying auxetic materials at the molecular level. GULP is a force-field based molecular modelling package which incorporates the ‘core-shell’ model for si mulating polarisability. A validation procedure was performed where the capability of GULP to reproduce the structural and mechanical properties of SOD (a zeolite for which the single crystalline elastic constants have been experimentally measured). It was found that not all GULP libraries (force-fields) could reproduce these properties, although the ‘Catlow 1992’ and ‘Sauer 1997’ libraries were found the produce good results. These libraries were then used t o study the all-silica forms of various ‘presumably auxetic’ zeolites. The simulations generally confi rmed the conclusions reported in earlier studies, and in particular, the fibrous zeolites THO , NAT and EDI where once again shown to be auxetic in the (001) plane. A study was also performed aimed at assessing the effect of interstitial species on the mechanical properties of NAT where it was shown that these species reduce the auxetic effect. This is very significant as once again we have confirmed the potential of these materials as molecular level auxetics, and hopefully, t hese results will result in generating more interest into the fascinating materials which could be used in many practical applications ( e.g. tuneable molecular sieves).
9
Content available remote Modelowanie numeryczne materiałów auksetycznych w warunkach obciążeń statycznych i dynamicznych
Stanisławek S., Morka A., Niezgoda T.
Mechanik
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2011
|
R. 84, nr 5-6
506-508
PL
Artykuł omawia zagadnienie komputerowej symulacji mechanicznych zachowań izotropowych materiałów auksetycznych pozbawionych wewnętrznych pustych przestrzeni. Poszukuje się odpowiedzi na pytanie: w jaki sposób zmiana strukturalnego auksetyka w materiał ciągły pozbawiony pustych wtrąceń może mieć wpływ na jego właściwości mechaniczne.
EN
Discussed are problems met in computer simulation of mechanical behavior of isotropic auxetic materials devoid of empty inner spaces. Explanation is searched to the question how the process of change from a structural auxetic into a solid substance devoid of empty inside spaces reflects the material mechanical properties.
10
Content available Production and study of polyether auxetic foam
Stręk A. M.
Mechanics and Control
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2010
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Vol. 29, no. 2
78-87
EN
The article describes the experiment consisting in production and study of auxetic open-cell polyether foam. In the introduction I briefly explain what auxetic materials are and list their main properties together with possible application areas. Next, detailed information about the background of the experiment is given: important material characteristics and extensive description of the procedure. Further, discussion of the results is presented, basing on microscopic imagery of the obtained auxetic foam. The article describes also tensile tests performed on the produced material and cites quantitative results in the form of text and graphs illustrating the Poisson ratio dependence on deformation, as well as stress-strain relations (true and engineering values). In the final part of the article conclusions are enclosed.
PL
Artykuł opisuje eksperyment polegający na laboratoryjnym wytworzeniu i badaniu właściwości auksetycznej otwarokomórkowej pianki polieterowej. We wstępie krótko opisane jest, czym są materiały auksetyczne, podane są ich najważniejsze własności oraz możliwe obszary zastosowań. Następnie przedstawione są szczegółowo informacje o samym eksperymencie: scharakteryzowano użyty materiał i przedstawiono sposób wytworzenia pianki. W kolejnej części artykułu znajdują się mikroskopowe obrazy struktury pianki wraz z komentarzem dotyczącym mechanizmów deformacji. Opisany jest także test na rozciąganie otrzymanej pianki auksetycznej; wyniki opatrzone są komentarzem oraz wykresami. Wykresy ilustrują zależności współczynnika Poissona od odkształcenia oraz relację naprężeń i odkształceń (inżynierskich oraz rzeczywistych). W ostatniej części zamieszczono uwagi podsumowujące.
11
Content available remote Tribological properties of auxetic and conventional polypropylene weft knitted fabrics
Uzun M., Patel I.
Archives of Materials Science and Engineering
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2010
|
Vol. 44, nr 2
120-125
EN
Purpose: The wear resistance and friction reducing properties of polymer fibres can be improved with negative Poisson's ratio behaviour. Poisson's ratio is defined as the ratio of transverse contraction strain to longitudinal extension strain in the direction of stretching force. Large number of materials have positive Poisson's ratio, however there are some materials which exhibit negative Poisson's ratio, they are termed auxetic materials. Auxetic materials present unique property that they expand in all directions when they are stretched and contract when compressed. This paper has highlighted, compared and discussed the variation between the modelling, theoretical and practical differences of auxetic materials wear behaviour. Design/methodology/approach: For the purpose of this work, auxetic and conventional fibres were produced by the melt spinning mechanism using extruder. The fibres physical properties were evaluated such as Poisson's ratio, fibre count, elongation, force and tenacity. Mono-filament fibres were used for fabrication of weft knitted fabrics; plain (1x1) structure was employed for knitting fabric. The wear resistance of the knitted fabrics were tested by using Nu-Martindale Abrasion and Pilling Tester and comparison were made. Findings: The abrasive wear test results demonstrated that the auxetic based weft knitted fabrics have superior wear behaviour than the conventional fibre based weft knitted fabrics. Practical implications: The experiment showed that the auxetic material is capable of sustaining large amount of abrasion compared to conventional fabric. Originality/value: The paper compare and discusse the variation between the modelling, theoretical and practical differences of auxetic materials wear behaviour.
12
Content available remote Propagation of solitary waves in rod made of material with negative Poisson’s ratio
Kołat P.
Vibrations in Physical Systems
|
2008
|
Vol. 23
195--198
EN
It is found the propagation of longitudinal solitary waves in an elastic rod made of material with negative Poisson’s ratio. It is used the difference scheme to solve the non-linear partial differential equation.
13
Content available remote Molecular auxetics
Wojciechowski K. W.
Vibrations in Physical Systems
|
2006
|
Vol. 22
49--52
14
Auksetyk - materiał o niekonwencjonalnych właściwościach
Śmiałkowska-Opałka M., Łandwijt M.
Techniczne Wyroby Włókiennicze
|
2006
|
R. 14, nr 1/2
18-24
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