Indentation Resilience of Conventional and Auxetic Foams

Chan, N; Evans, K. E.

doi:10.1177/0021955x9803400304

Cited by 207 publications

(173 citation statements)

References 11 publications

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“…This led to the discovery of numerous auxetic materials [1,2,, ranging from synthetic polymeric foams [10][11][12][13][14][15][16] to naturally occurring silicates and zeolites [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. Additionally, a number of auxetic models and structures have also been identified [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56].…”

Section: Introductionmentioning

confidence: 99%

On the mechanical properties and auxetic potential of various organic networked polymers

Grima

Attard

Cassar

et al. 2008

Molecular Simulation

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We simulate and analyse three types of two-dimensional networked polymers which have been predicted to exhibit on-axis auxetic behaviour (negative Poisson's ratio), namely (1) polyphenylacetylene networks that behave like flexing re-entrant honeycombs, commonly referred to as ‘reflexynes’, (2) polyphenylacetylene networks that mimic the behaviour of rotating triangles, commonly referred to as ‘polytriangles’ and (3) networked polymers built from calix[4]arene units. More specifically, we compute and compare their in-plane off-axis mechanical behaviour, in particular their off-axis Poisson's ratios and show that in some cases, the sign and magnitude of the Poisson's ratio are dependent on the direction of loading. We propose two functions that can provide a measure for the extent of auxeticity for such anisotropic materials and show that the polytriangles are predicted as the most auxetic when compared with the other networks with the reflexyne re-entrant networks being the least auxetic.peer-reviewe

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Section: Introductionmentioning

confidence: 99%

On the mechanical properties and auxetic potential of various organic networked polymers

Grima

Attard

Cassar

et al. 2008

Molecular Simulation

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“…This process makes significant changes to the microstructure that bring about the change in elastic properties. 14 Existing models of auxetic foam reflect this process by considering an altered cell model. Masters and Evans 17 use a re-entrant cell or hourglass shape while Smith et al 18 consider a regular network that has certain connections broken.…”

Section: Foam and Granular Modelsmentioning

confidence: 99%

Effect of heterogeneity on the elastic properties of auxetic materials

Gaspar

Smith

Evans

2003

Journal of Applied Physics

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Auxetic materials are gaining practical interest for their unusual and sometimes extreme mechanical response. The process of modeling these materials so far has highlighted a number of microstructural properties that are key to these materials. However these models often rely on the assumption of homogeneity and order within the materials. Practically, a homogeneous auxetic material such as foam is unlikely to be manufactured. This work seeks to analyze the effect of fluctuations within the microstructure of the material. Numerical results show the effect of fluctuations in an auxetic granular substance and analytical work indicates the relation between microscale fluctuations and the elastic moduli for a general auxetic material.

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“…Auxetic foams are characterised by a negative Poisson's ratio; when compressed in one direction these materials contract in one or more perpendicular directions. This contraction and densification under the region of contact can lead to increased indentation resistance [30], which could be particularly beneficial to snow-sport safety devices. The indentation resistance (H) for an isotropic material is related to Poisson's ratio (ν) and Young's modulus (E),…”

Section: Introductionmentioning

confidence: 99%

Auxetic Foam for Snow-Sport Safety Devices

Allen

Duncan

Foster

et al. 2017

Snow Sports Trauma and Safety

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Skiing and snowboarding are popular snow-sports with inherent risk of injury. There is potential to reduce the prevalence of injuries by improving and implementing snow-sport safety devices with the application of advanced materials. This chapter investigates the application of auxetic foam to snow-sport safety devices. Composite pads-consisting of foam covered with a semi-rigid shell-were investigated as a simple model of body armour and a large 70 × 355 × 355 mm auxetic foam sample was fabricated as an example crash barrier. The thermo-mechanical conversion process was applied to convert open-cell polyurethane foam to auxetic foam. The composite pad with auxetic foam absorbed around three times more energy than the conventional equivalent under quasi-static compression with a concentrated load, indicating potential for body armour applications. An adapted thermo-mechanical process-utilising through-thickness rods to control in-plane compression-was applied to fabricate the large sample with relatively consistent properties throughout, indicating further potential for fabrication of a full size auxetic crash barrier. Further work will create full size prototypes of snow-sport safety devices with comparative testing against current products.

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Indentation Resilience of Conventional and Auxetic Foams

Cited by 207 publications

References 11 publications

On the mechanical properties and auxetic potential of various organic networked polymers

On the mechanical properties and auxetic potential of various organic networked polymers

Effect of heterogeneity on the elastic properties of auxetic materials

Auxetic Foam for Snow-Sport Safety Devices

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