The Effects of Processing on the Topology and Mechanical Properties of Negative Poisson’s Ratio Foams

Alderson, Andrew; Alderson, K. L.; Davies, Philip; Smart, G.

doi:10.1115/imece2005-82404

Cited by 34 publications

(75 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Anisotropy and uniaxial Poisson's ratios can be increased in open cell foams by stretching parallel to cell rise during fabrication [34,35,49] rather than compressing (which typically reduces anisotropy and Poisson's ratio) [36]. Given that the open cell layer can reduce impact severity.…”

Section: Discussionmentioning

confidence: 99%

“…Auxetic foams (with a negative Poisson's ratio) have shown higher energy absorption than their conventional counterparts [31][32][33], and can be tailored to test the effect of mechanical characteristics (i.e., Young's modulus and Poisson's ratio) in complex situations (i.e., impact tests) [34,35]. Lakes originally fabricated auxetic foams through a compression and heat treatment process [36].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Application of Auxetic Foam in Sports Helmets

et al. 2018

Self Cite

View full text Add to dashboard Cite

This investigation explored the viability of using open cell polyurethane auxetic foams to augment the conformable layer in a sports helmet and improve its linear impact acceleration attenuation. Foam types were compared by examining the impact severity on an instrumented anthropomorphic headform within a helmet consisting of three layers: a rigid shell, a stiff closed cell foam, and an open cell foam as a conformable layer. Auxetic and conventional foams were interchanged to act as the helmet's conformable component. Attenuation of linear acceleration was examined by dropping the combined helmet and headform on the front and the side. The helmet with auxetic foam reduced peak linear accelerations (p < 0.05) relative to its conventional counterpart at the highest impact energy in both orientations. Gadd Severity Index reduced by 11% for frontal impacts (38.9 J) and 44% for side impacts (24.3 J). The conformable layer within a helmet can influence the overall impact attenuating properties. The helmet fitted with auxetic foam can attenuate impact severity more than when fitted with conventional foam, and warrants further investigation for its potential to reduce the risk of traumatic brain injuries in sport specific impacts.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Application of Auxetic Foam in Sports Helmets

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…Foam slabs having dimensions of the order of a few 10s of centimetres have been successfully produced [40,41]. Foams displaying isotropic and anisotropic mechanical properties can be produced [41,42]. Microcellular foam and closed-cell foam have also both been converted into auxetic form [43,44].…”

Section: Foamsmentioning

confidence: 99%

“…Figure 5 shows micrographs of a polyurethane foam before and after conversion to auxetic form, showing a contorted three-dimensional re-entrant topology for the auxetic foam compared to the regular convex cell structure of the conventional starting foam material [45]. [42] have potential as free-layer damping materials where a high bending stiffness and a low compressional modulus are required to produce in-plane extensional damping properties (to damp flexural waves present in the substrate) and a low through-thickness compressional wave speed.…”

Section: Foamsmentioning

confidence: 99%

Auxetic materials

Alderson

2007

Proceedings of the Institution of Mechanical Engineers, Part G:

409

286

View full text Add to dashboard Cite

Abstract:The current status of research into auxetic (negative Poisson's ratio) materials is reviewed, with particular focus on those aspects of relevance to aerospace engineering. Developments in the modelling, design, manufacturing, testing, and potential applications of auxetic cellular solids, polymers, composites, and sensor/actuator devices are presented. Auxetic cellular solids in the forms of honeycombs and foams are reviewed in terms of their potential in a diverse range of applications, including as core materials in curved sandwich panel composite components, radome applications, directional pass band filters, adaptive and deployable structures, MEMS devices, filters and sieves, seat cushion material, energy absorption components, viscoelastic damping materials, and fastening devices. The review of auxetic polymers includes the fabrication and characterization of microporous polymer solid rods, fibres, and films, as well as progress towards the first synthetic molecular-level auxetic polymer. Potential auxetic polymer applications include self-locking reinforcing fibres in composites, controlled release media, and self-healing films. Auxetic composite laminates and composites containing auxetic constituents are reviewed and enhancements in fracture toughness, and static and low velocity impact performance are presented to demonstrate potential in energy absorber components. Finally, the potential of auxetics as strain amplifiers, piezoelectric devices, and structural health monitoring components is presented.

show abstract

“…The conversion process can be applied to a range of materials [e.g. 34,38], and highly anisotropic auxetic foam can be obtained by applying different amounts of compression in each direction during fabrication [39]. When applying the thermo-mechanical process, there is, as yet, no consensus regarding the best heating time and temperature combination to maximise auxetic behaviour.…”

Section: Auxetic Foammentioning

confidence: 99%

Auxetic Foam for Snow-Sport Safety Devices

Allen

Duncan

Foster

et al. 2017

Snow Sports Trauma and Safety

Self Cite

View full text Add to dashboard Cite

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.

show abstract

The Effects of Processing on the Topology and Mechanical Properties of Negative Poisson’s Ratio Foams

Cited by 34 publications

References 16 publications

Application of Auxetic Foam in Sports Helmets

Application of Auxetic Foam in Sports Helmets

Auxetic materials

Auxetic Foam for Snow-Sport Safety Devices

Contact Info

Product

Resources

About