Effect of heterogeneity on the elastic properties of auxetic materials

Gaspar, N.; Smith, Christopher W.; Evans, K.

doi:10.1063/1.1614847

Cited by 18 publications

(9 citation statements)

References 22 publications

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“…A cursory glance at an auxetic foam reveals that like most materials their structure (both geometric and mechanical) vary as you move through the material. Previous work [16] begins to address the issue of disorder (heterogeneity) within auxetic materials. Other work in the context of granular materials [17] shows how important a correct use of heterogeneity is for the prediction of elastic moduli in a material with microstructure.…”

Section: Introductionmentioning

confidence: 99%

Quantitative analysis of the microscale of auxetic foams

Gaspar¹,

Smith

Miller

et al. 2005

Physica Status Solidi (b)

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The auxetic foams first produced by Lakes have been modelled in a variety of ways, each model trying to reproduce some observed feature of the microscale of the foams. Such features include bent or broken ribs or inverted angles between ribs. These models can reproduce the Poisson's ratio or Poisson's function of auxetic foam if the model parameters are carefully chosen. However these model parameters may not actually reflect the internal structure of the foams. A big problem is that measurement of parameters such as lengths and angles is not straightforward within a 3-d sample. In this work a sample of auxetic foam has been imaged by 3-d X-ray computed tomography. The resulting image is translated to a form that emphasises the geometrical structure of connected ribs. This connected rib data are suitably analysed to describe both the microstructural construction of auxetic foams and the statistical spread of structure, that is, the heterogeneity of an auxetic foam. From the analysis of the microstructure, observations are made about the requirements for microstructural models and comparisons made to previous existing models. From the statistical data, measures of heterogeneity are made that will help with future modelling that includes the heterogeneous aspect of auxetic foams.

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Section: Introductionmentioning

confidence: 99%

Quantitative analysis of the microscale of auxetic foams

Gaspar¹,

Smith

Miller

et al. 2005

Physica Status Solidi (b)

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“…In the past 20 years, materials with negative Poisson's ratios (auxetic materials), which expand laterally when stretched longitudinally, have been of significant scientific interest and have considerable practical applications [1][2][3][4][5][6]. It has been known to be theoretically possible since Love [7].…”

Section: Introductionmentioning

confidence: 99%

The manufacture and characterisation of a novel, low modulus, negative Poisson’s ratio composite

Miller¹,

Hook²,

Smith³

et al. 2009

Composites Science and Technology

175

144

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Abstract.Relatively few negative Poisson's ratio (auxetic) composites have been manufactured and characterised and none with inherently auxetic phases. This paper presents the use of a novel double helix yarn that is shown to be auxetic, and an auxetic composite made from this yarn in a woven textile structure. This is the first reported composite to exhibit auxetic behaviour using inherently auxetic yarns. Importantly, both the yarn and the composite are produced using standard manufacturing techniques and are therefore potentially useful in a wide range of engineering applications.

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“…4(c) and 4(b), respectively, for dimensionless thickness h/l = 0.2 using the shear correction factor k = 5/(6 -v). Based on Koender's [34] theory for pre dicting spatial features within a heterogeneous material under a persistent strain path, Gaspar [35] and Gaspar et al [36] showed that a valid elastic moduli can be obtained if the continuum length is at least 5 mean cell grain diameters. 4(c) and 4(b) show that there exists a boundary that indicates the comparative shear-to-bending deformation ratio for both types of load distributions.…”

Section: Si (11) (31) = (13) (51) = (15) (33) (71) = (17) (5mentioning

confidence: 99%

Shear Deformation in Rectangular Auxetic Plates

Lim

2014

Journal of Engineering Materials and Technology

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S h ear D efo rm atio n in R ectan g u lar A uxetic P latesSolids that exhibit negative Poisson's ratio are called auxetic materials. This paper examines the extent of transverse shear deformation with reference to bending deforma tion in simply supported auxetic plates as a ratio of Mindlin-to-Kirchhoff plate deflection for polygonal plates in general, with special emphasis on rectangular plates. Results for square plates show that the Mindlin plate deflection approximates the Kirchhoff plate deflection not only when the plate thickness is negligible, as is obviously known, but also when (a) the Poisson's ratio of the plate is very negative under all load distributions, as well as (b) at the central portion of the plate when the load is uniformly distributed. Hence geometrically thick plates are mechanically equivalent to thin plates if the plate Poisson's ratio is sufficiently negative. The high suppression of shear deformation in favor o f bending deformation in auxetic plates suggests its usefulness for bending-based plate sensors that require larger difference in the in-plane strains between the opposing plate surfaces with minimal transverse deflection.

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Effect of heterogeneity on the elastic properties of auxetic materials

Cited by 18 publications

References 22 publications

Quantitative analysis of the microscale of auxetic foams

Quantitative analysis of the microscale of auxetic foams

The manufacture and characterisation of a novel, low modulus, negative Poisson’s ratio composite

Shear Deformation in Rectangular Auxetic Plates

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