Non-linear properties of polymer cellular materials with a negative Poisson's ratio

Choi, Jeong-Sun; Lakes, Roderic S.

doi:10.1007/bf01166005

Cited by 234 publications

(187 citation statements)

References 11 publications

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“…Despite its simplicity, the model is able to match the overall behaviour of the auxetic foam with only three parameters! .2)) with the best-fit parameters from table 1 applied to the data in [16]. For what concerns the stress-stretch curve in figure 9, the model closely follows the experimental data up to 50% of deformation both in tension and compression.…”

Section: Experimental Data Analysismentioning

confidence: 58%

“…We use the proposed constitutive equation to explain some experimental data on Scott's foams by Lakes and co-workers [16]. These data, shown in figures 8-10, are indeed representative of a large class of auxetic materials as a similar behaviour has been observed in open cell-compliant polyurethane foams [7], chiral honeycombs [17] and even in warp knit auxetic fabrics [18].…”

Section: Introductionmentioning

confidence: 64%

“…This behaviour is not seen in the experimental data, and therefore the choice f > 0 is crucial in describing real-world materials. The reason why the previous approach is not sufficient to describe auxetic materials is apparent from the papers on structural aspects of auxetic foams [5,6,16,22]. Indeed, the negative Poisson ratio effect is caused by microstructure changes that the material undergoes when deformed.…”

Section: Blatz-ko Auxetic Modelmentioning

confidence: 99%

See 2 more Smart Citations

A continuum hyperelastic model for auxetic materials

Ciambella

Saccomandi

2014

Proc. R. Soc. A.

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We propose a simple mathematical model to describe isotropic auxetic materials in the framework of the classical theory of nonlinear elasticity. The model is derived from the Blatz-Ko constitutive equation for compressible foams and makes use of a nonmonotonic Poisson function. An application to the modelling of auxetic foams is considered and it is shown that the material behaviour is adequately described with only three constitutive parameters.

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Section: Experimental Data Analysismentioning

confidence: 58%

Section: Introductionmentioning

confidence: 64%

Section: Blatz-ko Auxetic Modelmentioning

confidence: 99%

See 1 more Smart Citation

A continuum hyperelastic model for auxetic materials

Ciambella

Saccomandi

2014

Proc. R. Soc. A.

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“…No substantial influence of the cushion thickness has been observed. In addition, the negative Poisson's ratio foams showed a reasonably linear relationship between stress and strain up to more than 40% compressive strain, compared to 5% strain of the conventional foams (Lakes, 1987;Choi and Lakes, 1992). Therefore, the densification of foam due to bottoming or long term creep can be largely reduced, and then the incremental stiffness during the use period will be much more controllable than with traditional foam cushions.…”

Section: Introductionmentioning

confidence: 81%

Analytical parametric analysis of the contact problem of human buttocks and negative Poisson's ratio foam cushions

Wang

Lakes

2002

International Journal of Solids and Structures

124

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Analytical investigations on the contact problems between two homogeneous and isotropic soft bodies were performed to simulate the contact of human buttocks and seat cushions. The cushion materials' Poisson's ratio were allowed to be negative. The human buttocks were modeled as an ideal sphere with radius 15 cm, and assumed to have a low Young's modulus and a Poisson's ratio close to 0.5. These parameters were held constant during our analysis. Peak contact pressure was reduced by adjusting the contour curvature of cushions according to Hertz theory, as expected. Moreover, analysis by both the Hertz model and a finite thickness 3D elasticity model showed that using negative Poisson's ratio cushions could further reduce the pressure. Negative Poisson's ratio cushions may be beneficial in the prevention of pressure sores or ulcers in the sick and in reduction of pressure-induced discomfort in seated people.

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“…The volumetric compression ratios (VCR = Final/Initial Volume) applied during fabrication (typically 0.2 to 0.5 [24]) are considered to have the largest effect on mechanical properties [25], but thermal conditions are also critical. Applying compression and heating within windows of temperature and time (conversion windows) produces NPR samples.…”

Section: Introductionmentioning

confidence: 99%

Controlling Density and Modulus in Auxetic Foam Fabrications—Implications for Impact and Indentation Testing

Duncan¹,

Allen²,

Foster³

et al. 2018

The 12th Conference of the International Sports Engineering Association

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Foams are commonly used for cushioning in protective sporting equipment. Volumetrically compressing open-cell polyurethane foam buckles cell ribs creating a re-entrant structure-set by heating then cooling-which can impart auxetic behaviour. Theoretically, auxetic materials improve impact protection by increasing indentation resistance and energy absorption, potentially reducing sporting injuries and burdens on individuals, health services and national economies. In previous work, auxetic foam exhibited ~3 to ~8 times lower peak force (compared to its conventional counterpart) under impacts adopted from tests used to certify protective sporting equipment. Increases to the foam's density and changes to stress/strain relationships (from fabrication) mean Poisson's ratio's contribution to reduced peak forces under impact is unclear. This work presents a simple fabrication method for foam samples with comparable density and linear stress/strain relationship, but different Poisson's ratios ranging between 0.1 and −0.3, an important step in assessing the Poisson's ratio's contribution to impact force attenuation.

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Non-linear properties of polymer cellular materials with a negative Poisson's ratio

Cited by 234 publications

References 11 publications

A continuum hyperelastic model for auxetic materials

A continuum hyperelastic model for auxetic materials

Analytical parametric analysis of the contact problem of human buttocks and negative Poisson's ratio foam cushions

Controlling Density and Modulus in Auxetic Foam Fabrications—Implications for Impact and Indentation Testing

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