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

Wang, Yun-Che; Lakes, Roderic S.

doi:10.1016/s0020-7683(02)00379-7

Cited by 119 publications

(76 citation statements)

References 21 publications

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“…Since then, a large number of research papers, patents, and theses have been published related to the fabrication, characterization, theoretical, and mechanical modeling of such foams (22,(60)(61)(62)(63)(64)(65)(66)(67)(68)(69)(70)(71)(72)(73)(74)(75)(76)(77)(78). Their enhanced mechanical properties such as indentation resistance, shear resistance, fracture toughness, viscoelastic loss, sound absorption, and high-density were reported by authors in Refs.…”

Section: Auxetic Polymeric Foamsmentioning

confidence: 99%

Three decades of auxetic polymers: a review

Bhullar

2015

E-Polymers

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Developments in design and technology in the engineering and medical fields necessitate the use of smart and high-performance materials to meet higher engineering specifications. The general requirements of such materials include a combination of high stiffness and strength with significant weight savings, resistance to corrosion, chemical resistance, low maintenance, and reduced costs. Over the last three decades, it has been demonstrated that auxetic materials offer a huge potential for the fields of engineering, natural sciences, and biomedical engineering, and for many other industries, including the aerospace and defense industries, through their unique deformation mechanism and measured enhancements in mechanical properties. To meet future engineering challenges, auxetic materials are increasingly being recognized as integral components of smart and advanced materials. Although materials with a negative Poisson's ratio have been known since the early 1900s, they did not capture researchers' attention until the late 1980s. Since 1991, these materials have been known as auxetic materials. Since then, their benefits and applications have been expanded to all major classes of materials such as metals, ceramics, polymers, and composites, and they are also now being used in engineering applications. The goal of this review was to present the development of auxetic polymers, which were first fabricated in the form of polyurethane foam approximately three decades ago and are now used in the fabrication of non-woven nano/ micropolymeric structures. This review could provide useful information for the future development of auxetic polymers.

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Section: Auxetic Polymeric Foamsmentioning

confidence: 99%

Three decades of auxetic polymers: a review

Bhullar

2015

E-Polymers

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“…Materials exhibiting such counterintuitive behaviour, known as auxetics, are of great interest not only because they are rare, but also because of their numerous potential applications in various fields, such as the design of fasteners 12 , prostheses 13 , pizeocomposites 14,15 , filters 16 , earphones 17 , seat cushions 18,19 and superior dampers 20 . Materials with negative Poisson's ratios have been extensively studied since Lakes 1 reported a negative Poisson's ratio in a reentrant foam structure.…”

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confidence: 99%

Negative Poisson’s ratios in metal nanoplates

et al. 2014

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The Poisson's ratio is a fundamental measure of the elastic-deformation behaviour of materials. Although negative Poisson's ratios are theoretically possible, they were believed to be rare in nature. In particular, while some studies have focused on finding or producing materials with a negative Poisson's ratio in bulk form, there has been no such study for nanoscale materials. Here we provide numerical and theoretical evidence that negative Poisson's ratios are found in several nanoscale metal plates under finite strains. Furthermore, under the same conditions of crystal orientation and loading direction, materials with a positive Poisson's ratio in bulk form can display a negative Poisson's ratio when the material's thickness approaches the nanometer scale. We show that this behaviour originates from a unique surface effect that induces a finite compressive stress inside the nanoplates, and from a phase transformation that causes the Poisson's ratio to depend strongly on the amount of stretch.

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“…It can be hypothesized that a better distribution of the pressure at the interface between the glove and the human hand will result less damaging to skin tissue and to blood capillaries, even if associated with higher overall levels of vibration transmitted to the hand. In fact, according to Finite Element simulations on indentation resistance on auxetic open cell PU foams [24,25], conventional foams present uneven distributions of the deformation fields. The auxetic foam, instead, tends to enfold around the indentation zone, providing a wrapping effect not present in the conventional cellular material.…”

Section: Discussionmentioning

confidence: 99%

Dynamic behavior and damping capacity of auxetic foam pads

et al. 2006

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A novel set of auxetic (negative Poisson's ratio) open cell polyurethane foam has been developed and tested under dynamic loading conditions to assess the viscoelastic response under white noise random excitation and compressive cycling. Foam pads normalized to standard ISO 13753 have been tested at room temperature and frequency bandwidth 10-500 Hz to assess transmissibility characteristics for possible antivibration glove applications. The results show that the ISO 13753 normalized transmissibility for these foams falls below 0.6 above 100 Hz, with lower peak maximum stresses under indentation compared to conventional open cell solids. These results suggest possible use of the auxetic foam for pads or linens against « white fingers« vibration applications. Further tests have been conducted on cyclic compressive loading up to 3 Hz and loading ratios of 0.95 for loading histories up to 100000 cycles. The damping capacity of the auxetic foams showed and increase by a factor 10 compared to the conventional foams used to manufacture the negative Poisson's ratio ones, and stiffness degradation stabilized after few tens on cycles. [4]. The large number of applications is related to the peculiar deformation mechanisms of auxetic configurations. In fact, and auxetic (negative Poisson's ratio) materials expand in all directions when pulled in only one, leading to an unusual volume change of the solid itself. The negative Poisson's ratio behaviour does not contradict the classical theory of elasticity. A homogeneous, isotropic, thermodynamically correct 3D solid has a potential Poisson's ratio range between -1.0 and 0.5, while the magnitude of the Poisson's ratio can be even larger in the case of anisotropic solids. The dynamic behaviour of auxetic materials has been investigated by several authors [5,6,7,8]. The possible use of auxetic materials for viscoelastic damping applications has been examined in [9], where biphasic auxetic composite showed loss tangent exceeding lower Voigt limit, and close to Hashin upper bound. In recent papers [10,11] increases in loss factor and storage moduli have been shown for auxetic PU foams manufactured using a modified route from the classical production layout. In the field of vibration absorber pads, testing of antivibration glove cushioning materials has been the subject of several research studies [12,13] which have lead to the establishment ISO standard 13753:1999 [14], which defines a method for measuring the mechanical transmissibility of glove cushioning materials. The method determines the impedance of the material when loaded by a mass providing a compression force equivalent to that found when the material is gripped by the hand. This is done by measuring the transfer function of the mass-loaded material at all the required frequencies. The vibration transmission when loaded by the hand is computed using standard values of hand-arm impedance and the measured values of the material impedance. The impedances used in this International Standard are for the palm of the...

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

Cited by 119 publications

References 21 publications

Three decades of auxetic polymers: a review

Three decades of auxetic polymers: a review

Negative Poisson’s ratios in metal nanoplates

Dynamic behavior and damping capacity of auxetic foam pads

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