Comparison of Contact Stress Distribution for Foam Seat and Seat of Auxetic Spring Skeleton

Janus-Michalska, M.; Jasińska, Dorota; Smardzewski, Jerzy

doi:10.2478/ijame-2013-0004

Cited by 15 publications

(5 citation statements)

References 10 publications

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“…Wang et al [53] reported that auxetic cushions could reduce the pressure which could bring more comfort. The work of Michalska et al [243] further proofed that auxetic materials could reduce contact stress concentrations by conducting numerical simulations on a seat with an auxetic polyamide spring skeleton. In the work of Sanami et al [244], through numerical simulations, a new type of auxetic honeycomb was reported to have potential in helmet applications, along with indentation test of auxetic and non-auxetic foams for evaluating the applications of protective pads and running shoes.…”

Section: Protective Devicesmentioning

confidence: 96%

Auxetic metamaterials and structures: a review

Ren

Das

Tran

et al. 2018

Smart Mater. Struct.

716

331

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Materials and structures with negative Poisson’s ratio exhibit a counter-intuitive behaviour. Under uniaxial compression (tension), these materials and structures contract (expand) transversely. The materials and structures that possess this feature are also termed as ‘auxetics’. Many desirable properties resulting from this uncommon behaviour are reported. These superior properties offer auxetics broad potential applications in the fields of smart filters, sensors, medical devices and protective equipment. However, there are still challenging problems which impede a wider application of auxetic materials. This review paper mainly focuses on the relationships among structures, materials, properties and applications of auxetic metamaterials and structures. The previous works of auxetics are extensively reviewed, including different auxetic cellular models, naturally observed auxetic behaviour, different desirable properties of auxetics, and potential applications. In particular, metallic auxetic materials and a methodology for generating 3D metallic auxetic materials are reviewed in details. Although most of the literature mentions that auxetic materials possess superior properties, very few types of auxetic materials have been fabricated and implemented for practical applications. Here, the challenges and future work on the topic of auxetics are also presented to inspire prospective research work. This review article covers the most recent progress of auxetic metamaterials and auxetic structures. More importantly, several drawbacks of auxetics are also presented to caution researchers in the future study.

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Section: Protective Devicesmentioning

confidence: 96%

Auxetic metamaterials and structures: a review

Ren

Das

Tran

et al. 2018

Smart Mater. Struct.

716

331

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“…[30] Utilizing AM techniques, metamaterials with highly complex geometries, exploiting zero Poisson ratio (ZPR) and negative Poisson ratio (NPR) geometries, can be manufactured. [31][32][33] Metamaterials have exotic geometries that exploit the Poisson ratio of a re-entrant unit cell [30,34] and can integrate soft and stiff re-entrant unit cells into the same structure. Poisson's ratio is defined as the ratio between the transverse and axial strains.…”

Section: Doi: 101002/adem202300356mentioning

confidence: 99%

Additive Manufacturing of Composite Foam Metamaterial Springs for Vibration Isolation

Zolfagharian,

Picken,

Bodaghi

et al. 2023

Adv Eng Mater

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This research introduces a novel approach for reducing the vibrations experienced by passengers in vehicles using metamaterials embedded in polyurethane foam to improve the existing vibration isolation capacity of car seats. An exploration of quasi‐zero and negative stiffness metamaterials has been conducted to develop metamaterial springs that exhibit a region of high‐static and low‐dynamic stiffness to achieve vibration isolation. Metamaterials were developed using low‐cost open‐source additive manufacturing methods and thermoplastic polyurethane filament. This investigation followed a process of determining the geometric, material, and systemic design requirements, to identify the quasi‐zero and negative stiffness force‐displacement regions. Small‐scale models of a car seat were developed by embedding the designed metamaterials into different grades of polyurethane foam and completing static and dynamic testing. The results demonstrated practical applications for implementing metamaterial springs into polyurethane foam to enhance vibration isolation under dynamic loading. The developed material library, and the key geometric variables in the metamaterial design allow for application specific solutions where the selection of the appropriate metamaterial and foam combination can be tailored to suit the system requirements.This article is protected by copyright. All rights reserved.

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“…In particular, the capability to swell the areas of the fabric structure that are in tension offers the opportunity to obtain a sort of 'personalised' cushion adaptable to the different anatomic configurations of the users e to their specific loading conditions. It has been recently clarified, though only numerically, that discomfort could be theoretically reduced by the application of an auxetic foam skeleton (in the relevant simulation the material selected is nylon): in particular, progressive load application would be advantageous, meaning that the seat is compliant for a smaller load, while becoming stiffer for increasing loads (Janus- Michalska et al, 2013). In other words, seat becomes therefore adaptable to the volume, weight and movement of the user, even if this is abrupt or repeated.…”

Section: Chiral Chairmentioning

confidence: 99%

Study and development of concepts of auxetic structures in bio-inspired design

Santulli

Langella²

2016

IJSDES

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This work discusses the experience of using auxetic (negative Poisson's ratio) materials in different design objects, including chairs, bags, seat belts, etc., developed by the authors with their students. Auxetics have become of interest in engineering, whenever a support instead of a pronounced flexure, of a cellular, therefore lightweight material, is desirable. Structures have been calculated and modelled as chiral with defined geometrical parameters and then applied to concepts with the fabrication of real models using neoprene or generally rubbery material. Indications on the possible sensations of the user are suggested, which provided rationale for likely improved comfort and/or desirability of contact. Limitations of this study in terms of material experience appear the use of a single material as for auxetic properties and the focusing on one single possible auxetic structure, the chiral one. Despite this, this could be considered as a starting point for a possible database of material experience on the use of auxetics. From these considerations, it appears as the use of auxetic structures would lead to a more sustainable scenario for these objects, especially because improved user's experience would extend their duration of life and lead to a lower rate of discarded pieces.

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Comparison of Contact Stress Distribution for Foam Seat and Seat of Auxetic Spring Skeleton

Cited by 15 publications

References 10 publications

Auxetic metamaterials and structures: a review

Auxetic metamaterials and structures: a review

Additive Manufacturing of Composite Foam Metamaterial Springs for Vibration Isolation

Study and development of concepts of auxetic structures in bio-inspired design

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