Auxetic springs for seating

Smardzewski, Jerzy

doi:10.3906/tar-1204-64

Cited by 4 publications

(2 citation statements)

References 76 publications

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“…Auxetic materials could be particularly useful as sports materials due to a number of superior features they exhibit [3,6,7]. These include an enhanced ability to absorb impacts and resist indentation compared to their conventional [8][9][10][11][12][13][14][15][16][17][18][19][20] properties which arise from the fact that auxetic materials tend to densify more extensively upon contraction. They also have a natural ability to form 'domeshaped' surfaces, a useful property if used to manufacture helmets, knee or elbow pads [21][22][23][24], since the presence of a NPR permits concurrent orthogonal elongation on the outer surface and concurrent orthogonal contractions on the inner surface.…”

Section: Introductionmentioning

confidence: 99%

What it could feel like to press on an auxetic: effect of Poisson’s ratio on the indenter

Attard,

Gatt,

Caruana-Gauci

et al. 2023

Smart Mater. Struct.

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The behaviour of an indenter having a hard inner core and a softer outer shell, meant to emulate a human finger, pressing upon a sample covered with an isotropic negative/zero/positive Poisson’s top protective layer was investigated through static finite-element simulations. It was shown that if the material being indented had a comparable Young’s modulus to the outer shell of the indenter, a very negative Poisson’s ratio results in more pronounced deformations and stresses within the indenter due to the auxetic material offering a higher resistance to indentation. Pressing of an auxetic material with Poisson’s ratio of -0.90 having the same Young’s modulus as that of the softer outer core of the indenter (1MPa), was found to result in stresses in the indenter which were approximately double to those measured when pressing a conventional material with same Young’s modulus having Poisson’s ratio +0.45. This indicates that auxetics with a very high negative Poisson’s ratio may feel more uncomfortable when pressed with a finger compared to materials of the same Young’s modulus having a conventional positive Poisson’s ratio. However, it was also shown that in such scenarios, the auxetic protective layer being indented could be made much thinner whilst still retaining the same functionality. In fact, the simulations suggest that a conventional material with Poisson’s ratio +0.45 indents more than five times as much as an auxetic material with Poisson’s ratio of -0.90 having the same Young’s modulus of 1MPa. It was also shown that in situations where the material being indented had a much higher Young’s modulus to that of the indenter, the deformations and stresses within the indenter are practically identical irrespective of the Poisson’s ratio, i.e. a human finger is unlikely to be able to perceive the difference between an auxetic and a conventional positive Poisson’s ratio material.

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Section: Introductionmentioning

confidence: 99%

What it could feel like to press on an auxetic: effect of Poisson’s ratio on the indenter

Attard,

Gatt,

Caruana-Gauci

et al. 2023

Smart Mater. Struct.

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show abstract

“…Limited numbers of studies handle the subject of auxetic materials and optimization techniques in the furniture industry. Those studies were established by Smardzewski et al [ 16 , 25 ]. The aim was to produce a model of an auxetic spring for seating furniture constructions.…”

Section: Introductionmentioning

confidence: 99%

Optimization of the Cross-Sectional Geometry of Auxetic Dowels for Furniture Joints

et al. 2023

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In this study, the aim was to optimize the cross-sectional geometry of auxetic dowels for furniture joints. For this purpose, two different sizes of auxetic dowels were chosen, one for frame- and the other for panel-type furniture joints for designing the cross-sectional geometry. Auxetic patterns that are created on the cross-sectional area cause deficiency of the materials, and this phenomenon decreases the modulus of elasticity (MOE) and increases the member stress. Accordingly, maximum MOE values and minimum Poisson’s ratio levels were determined for the optimum strength-auxetic behavior relation by means of a Monte Carlo method. Furthermore, Poisson’s ratio of the optimized dowel’s cross-section was confirmed with experimental tests, numerical analyses and analytical calculations. As a result, Poisson’s ratio values were obtained as negative values and confirmed, which means the dowels designed in this study had auxetic behavior. In conclusion, it could be said that studies should be conducted on the performance of auxetic dowels in both frame and panel furniture joints.

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Experimental and Numerical Study on Withdrawal Strength of Different Types of Auxetic Dowels for Furniture Joints

2020

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Studies on the application of the auxetic metamaterials and structures in furniture joints are very limited. However, they have huge potential for use in ready-to-assemble furniture. This study aimed to design and produce different types of auxetic dowels in 3D printing technology, and experimentally and numerically analyze the withdrawal strength of these dowels. In the scope of the study, 24 auxetic dowels with different types and size of inclusions, a different diameter of holes, and a non-auxetic reference dowel were designed and produced with appropriate muffs. Dowels were 3D printed from polyamide (PA12). Poisson’s ratios, withdrawal strength, contact pressures, and friction coefficients of dowels were determined theoretically by means of numerical analyses and real static compression tests. After the pre-production of dowels, the dowels with triangular inclusions have not been found to have sufficient strength and stiffness. Withdrawal strength of dowels decreased as the size of inclusions is decreased, or dowel hole diameter is increased. Furthermore, contact pressures and stresses in auxetic dowels were considerably lower than non-auxetic dowels under the withdrawal force.

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Auxetic springs for seating

Cited by 4 publications

References 76 publications

What it could feel like to press on an auxetic: effect of Poisson’s ratio on the indenter

What it could feel like to press on an auxetic: effect of Poisson’s ratio on the indenter

Optimization of the Cross-Sectional Geometry of Auxetic Dowels for Furniture Joints

Experimental and Numerical Study on Withdrawal Strength of Different Types of Auxetic Dowels for Furniture Joints

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