Auxetics and Other Systems of Anomalous Characteristics

Wojciechowski, Krzysztof W.; Scarpa, Fabrizio; Grima, Joseph N.; Alderson, Andrew

doi:10.1002/pssb.201800736

Cited by 10 publications

(10 citation statements)

References 25 publications

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“…It has also been found that novel properties, distinct from conventional or auxetic materials, arise when a composite structure is made from both conventional and auxetic materials. In addition to a recent comprehensive survey of auxetic materials and structures [ 37 ], the reader is also referred to a recent focus issue on “auxetics and other systems of anomalous characteristics” [ 38 , 39 , 40 , 41 , 42 ], as well as papers in this special issue [ 43 , 44 , 45 , 46 , 47 , 48 ].…”

Section: Introductionmentioning

confidence: 99%

Auxeticity of Concentric Auxetic-Conventional Foam Rods with High Modulus Interface Adhesive

Lim

2018

Materials

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While the rule of mixture is applicable for addressing the overall Poisson’s ratio of a concentrically aligned bi-layered rod under longitudinal loading, the same cannot be said for this rod under torsional loading due to the higher extent of deformation in the rod material further away from the torsional axis. In addition, the use of adhesives for attaching the solid inner rod to the hollow outer rod introduces an intermediate layer, thereby resulting in a tri-layered concentric rod if the adhesive layer is uniformly distributed. This paper investigates the effect of the adhesive properties on the overall auxeticity of a rod consisting of two concentrically aligned cylindrical isotropic foams with Poisson’s ratio of opposite signs under torsional loads. An indirect way for obtaining Poisson’s ratio of a concentrically tri-layered rod was obtained using a mechanics of materials approach. Results show that the auxeticity of such rods is influenced by the adhesive’s stiffness, Poisson’s ratio, thickness, and radius from the torsional axis.

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Section: Introductionmentioning

confidence: 99%

Auxeticity of Concentric Auxetic-Conventional Foam Rods with High Modulus Interface Adhesive

Lim

2018

Materials

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“…Suffice to mention that 2019 marks the 15th anniversary of the first of the "Auxetics and Related Systems" international meeting held near Poznan Poland, an initiative of Professor Krzysztof Witold Wojciechowski, which has now become the most important annual gathering for scientists working in this field and has led to numerous specialized publications. [30][31][32][33][34][35][36][37][38][39][40][41][42] Systems which exhibit more than one unusual property (e.g., a combination of negative linear compressibility, negative thermal expansion, and/or negative Poisson's ratio), or ones which show a considerable change in at least one of their properties in response to an external stimulus, are becoming increasingly desirable in view of practical applications where they can be used. In fact, in recent years, there have been extensive studies aimed at developing such systems and to further improve their properties.…”

Section: Introductionmentioning

confidence: 99%

“…Materials science and mechanics have also witnessed a number of important developments, some of which are of a fundamental nature, such as the verification, through models and experiments, that materials need not get thinner when stretched . This has led to the coining of new terms to describe these new systems, such as “auxetic” (from the Greek word auxetikos , a term coined by Kenneth E. Evans, to describe systems which exhibit a negative Poisson's ratio), “metamaterials” or “mechanical metamaterials,” a testimony of the growth of this and related fields . Suffice to mention that 2019 marks the 15th anniversary of the first of the “Auxetics and Related Systems” international meeting held near Poznan Poland, an initiative of Professor Krzysztof Witold Wojciechowski, which has now become the most important annual gathering for scientists working in this field and has led to numerous specialized publications …”

Section: Introductionmentioning

confidence: 99%

Smart Honeycomb “Mechanical Metamaterials” with Tunable Poisson's Ratios

Grima‐Cornish

Cauchi

Attard

et al. 2020

Physica Status Solidi (b)

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Mechanical metamaterials represent a class of deformable systems, which exhibit macroscopic deformations, mechanical, and/or thermal properties. These emerge due to the structure of their subunits rather than their materials composition and typically exhibit anomalous (normally negative) macroscopic structural, mechanical, or thermal property/properties caused by a change in shape/size of the system. Herein, a class of honeycombs is discussed, which push to the extreme the classical definition of “mechanical metamaterials,” exhibiting temperature‐tunable Poisson's ratio properties. More specifically, centrosymmetric honeycombs with T‐shaped joints constructed from different materials are shown to exhibit temperature‐dependent Poisson's ratio values, which can be either positive or negative (auxetic) depending on the external stimulus the system is subjected to. The sign and magnitudes of the Poisson's ratio values are explained in terms of particular geometries that these composite honeycomb systems attain at different temperature conditions. In particular, auxeticity is attributed to the transformation of the T‐shaped units to re‐entrant units. Practical aspects on how these properties may be achieved are discussed, including the possibility that the changes in shape, and hence Poisson's ratios, are induced via different extents of dryness on opposite surfaces of ligaments made from absorbent materials.

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“…Since its rediscovery in the late 1980s, [9][10][11][12][13] auxetic materials have been investigated for applications as cushions, [14,15] footwear, [16,17] aircraft structures, [18,19] shock and vibration control, [20][21][22][23][24][25] technical textiles, [26,27] chemical filters, [28][29][30][31] implants, [32][33][34][35][36][37] safety devices, [38] composite structures, [39,40] and even sport safety gear. [41,42] Further details of auxetic materials can be found in recent reviews by Saxena et al, [43] Lim, [44] Lakes, [45] and Ren et al [46] as well as recent special issues on auxetics in Physica Status Solidi B (e.g., previous studies [47][48][49] ), Materials (e.g., previous studies [50][51][52] ), and two monographs. [53,54] While auxeticity has often...…”

Section: Introductionmentioning

confidence: 99%

Maximum Stresses in Rectangular Auxetic Membranes

Lim

2020

Physica Status Solidi (b)

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Auxetic materials exhibit a negative Poisson's ratio. Herein, the performance of rectangular auxetic membranes, under uniform load, is evaluated in terms of the maximum stress encountered. To facilitate convenient calculation, empirical modeling is conducted on the exact solution to reproduce displacement coefficients that are sufficiently accurate. A dimensionless maximum stress is then introduced to allow the effect from the membrane's Poisson's ratio and aspect ratio to be directly observed. Results reveal that 1) the dimensionless maximum stress reduces monotonically and nonmonotonically for conventional and auxetic membranes, respectively, 2) for the same Poisson's ratio magnitude the stresses in auxetic membranes are lower than those from conventional ones, 3) the optimal Poisson's ratio, on the basis of dimensionless maximum stress minimization, falls within the negative range, and 4) the dimensionless maximum stress minimization is especially effective for square membranes as well as very long and narrow membranes. It is therefore recommended that material auxeticity be taken into account-alongside geometrical and other material properties-in designing membranes and highly compliant very thin plates.

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Auxetics and Other Systems of Anomalous Characteristics

Cited by 10 publications

References 25 publications

Auxeticity of Concentric Auxetic-Conventional Foam Rods with High Modulus Interface Adhesive

Auxeticity of Concentric Auxetic-Conventional Foam Rods with High Modulus Interface Adhesive

Smart Honeycomb “Mechanical Metamaterials” with Tunable Poisson's Ratios

Maximum Stresses in Rectangular Auxetic Membranes

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