scholarly journals Review of Mechanics and Applications of Auxetic Structures

2014 ◽  
Vol 2014 ◽  
pp. 1-17 ◽  
Author(s):  
Mariam Mir ◽  
Murtaza Najabat Ali ◽  
Javaria Sami ◽  
Umar Ansari
Keyword(s):  
Poisson’S Ratio ◽  
Deformation Mechanisms ◽  
Poisson's Ratio ◽  
Cellular Solids ◽  
Negative Poisson’S Ratio ◽  
Auxetic Materials ◽  
Different Types ◽  
Auxetic Structures ◽  
Negative Poisson's Ratio ◽  
Properties Of Materials

One of the important mechanical properties of materials is Poisson’s ratio, which is positive for most of the materials. However, certain materials exhibit “auxetic” properties; that is, they have a negative Poisson’s ratio. Thus auxetic and non-auxetic materials exhibit different deformation mechanisms. A specific microscopic structure in the auxetic materials is important for maintaining a negative Poisson’s ratio. Based on their distinct nature auxetic materials execute certain unique properties in contrast to other materials, which are reviewed in this paper. Thus auxetic materials have important applications in the biomedical field which are also a part of this review article. Many auxetic materials have been discovered, fabricated, and synthesized which differ on the basis of structure, scale and deformation mechanism. The different types of auxetic materials such as auxetic cellular solids, microscopic auxetic polymers, molecular auxetic materials, and auxetic composites have been reviewed comprehensively in this paper. Modeling of auxetic structures is of considerable importance and needs appropriate stress strain configurations; thus different aspects of auxetic modeling have also been reviewed. Packing parameters and relative densities are of prime importance in this regard. This review would thus help the researchers in determining and deciding the various aspects of auxetic nature for their products.

scholarly journals Giant negative Poisson’s ratio in two-dimensional V-shaped materials

2021 ◽  
Author(s):  
Xikui Ma ◽  
Jian Liu ◽  
Yingcai Fan ◽  
Weifeng Li ◽  
Jifan Hu ◽  
...  
Keyword(s):  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Two Dimensional ◽  
Auxetic Materials ◽  
Negative Poisson's Ratio ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

Two-dimensional (2D) auxetic materials with exceptional negative Poisson’s ratios (NPR) are drawing increasing interest due to the potentials in medicine, fasteners, tougher composites and many other applications. Improving the auxetic...

Design and fabrication of auxetic warp-knitted structures with a rotational hexagonal loop

2016 ◽  
Vol 86 (20) ◽  
pp. 2151-2157 ◽  
Author(s):  
Pibo Ma ◽  
Yuping Chang ◽  
Gaoming Jiang
Keyword(s):  
Poisson’S Ratio ◽  
Rotation Angle ◽  
Hexagonal Structure ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Two Dimensional ◽  
Auxetic Structures ◽  
Negative Poisson's Ratio ◽  
Novel Structures

In this paper, the design, manufacturing and characterization of two-dimensional warp-knitted textiles with auxetic performance is reported. Four warp-knitted structures based on a rotational hexagonal structure are produced, and these structures can lead to a negative Poisson’s ratio mathematically. The testing results have confirmed that the knitting structure of the front bar, as well as let-off values of the front bar’s chain parts, has a great effect, and auxetic properties of the warp-knitted textiles have a complicated relationship with the rotation angle. These novel structures can expand the applied area of auxetic structures.

Design, preparation, and characterization of auxetic weft backed weave fabrics based on Miura origami structure

2021 ◽  
pp. 004051752110505
Author(s):  
Qiaoli Xu ◽  
Longxin Gu ◽  
Gui Liu ◽  
Zhuoran Liu ◽  
Dongdong Lu ◽  
...  
Keyword(s):  
Poisson’S Ratio ◽  
Physical Map ◽  
Structure Type ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Auxetic Materials ◽  
Out Of Plane ◽  
Weaving Technology ◽  
Negative Poisson's Ratio

The metamaterials with negative Poisson’s ratio are called auxetic materials, which as a branch of metamaterials has drawn a lot of attention in many areas. Existing auxetic knitting textiles combine flexibility and auxeticity, however the loose structure has been a main disadvantage for its application. In this study, we fabricated Miura origami structure fabrics by weaving technology in order to acquire more stable auxetic textiles. The results show that using the combination of fabric structure type and elastic yarns, an origami structure can be realized in a jacquard loom. In the Miura origami structure, the crease pattern can be separated into three parts, unfolding areas, convex areas, and concave areas. One warp system and two weft systems are compounded together, in which a weft backed weave is used to get elastic floats in the convex and concave areas, and to make the fabrics bend to the concave side. The physical map showed that the fabrics had a clear Miura origami structure and the unfolding areas were flat and even. On the basis of the designed geometric pattern, weft backed weaves can be used to construct different folded areas, spandex wrapped PET (Polyester) and inelastic PET are selected as two weft systems for weaving. Meanwhile, the Miura origami fabrics exhibit distinct in-plane negative Poisson’s ratio and out-of-plane positive Poisson’s ratio. Apart from the Miura origami structure, other origami and paper-cut structures can be realized using this method, and these special auxetic textiles have potential in protective cloths, ornamented textiles, wearable devices, and flexible sensors.

Evaluation of Auxetic Polymeric Structures for Use in Protective Pads

2016 ◽  
Author(s):  
Chulho Yang ◽  
Hitesh D. Vora ◽  
Young Bae Chang
Keyword(s):  
Poisson’S Ratio ◽  
Polymeric Materials ◽  
Poisson's Ratio ◽  
Light Weight ◽  
Negative Poisson’S Ratio ◽  
Shock Absorption ◽  
Fused Deposition ◽  
Auxetic Materials ◽  
Negative Poisson's Ratio ◽  
Polymeric Structures

Auxetic materials, known as materials with negative Poisson’s ratio (NPR), have many promising application areas. However, there are only few natural and man-made materials such as certain living bone tissues, certain rocks and minerals, polymeric honeycombs, microporous polytetrafluoroethylene (PTFE), foams, and carbon-fiber-reinforced epoxy composite laminate panels that possess this property. In recent years, various auxetic material structures have been designed and fabricated for diverse applications that utilized normal materials which follow Hooke’s law but still show the NPR properties. One of the applications is body protection pads that are comfortable to wear and effective in protecting body parts by reducing impact force and preventing injuries in high-risk individuals such as elderly people, industry workers, law enforcement and military personnel, and sports players. It is important to develop new body protectors that best combine each individual’s requirements for wearing comfort (flexible, light-weight), ease of fitting (customized), ensured protection, and cost-effectiveness. The protection pad would be made from multilayer materials and adaptive structures to achieve unique multifunctional properties such as high hardness, impact toughness, light weight, and excellent shock absorption suitable for the needs. This paper reports an integrated theoretical, computational (finite element analysis), and experimental investigation conducted for typical auxetic polymeric materials that exhibit negative Poisson’s ratio (NPR) effect. Parametric 3D CAD models of auxetic polymeric structures such as re-entrant hexagonal cells and arrowhead were developed. Then, key structural characteristics of protectors were evaluated through static analyses of FEA models. In addition, impact/shock analyses were conducted through dynamic analyses of FEA models to validate the results obtained from the static analyses. Particularly, an advanced additive manufacturing (3D printing) technique was used to build prototypes of the auxetic polymeric structures. Specifically, three different materials typically used for FDM (Fused Deposition Modeling) technology such as Polylactic acid (PLA) and thermoplastic polyurethane (TPU) material (NinjaFlex® and SemiFlex®) were used for different stiffness and shock-absorption performances. The 3D printed prototypes were then tested and the results were compared with the computational prediction. The results showed that the auxetic material can be effective for body protection pads. Each structure and material had unique structural properties such as stiffness, Poisson’s ratio, and efficiency in shock absorption. Particularly, auxtetic structures showed better shock absorption performance than non-auxetic ones. The mechanism for ideal input force distribution or shunting could be suggested for designing protectors using various shapes, thicknesses, and materials of auxetic materials to reduce the risk of injury.

Vibration Transmission Loss of Auxetic Lattices

2015 ◽  
Vol 797 ◽  
pp. 282-289
Author(s):  
Eligiusz Idczak ◽  
Tomasz Strek
Keyword(s):  
Dynamic Behavior ◽  
Poisson’S Ratio ◽  
Natural Frequencies ◽  
Transmission Loss ◽  
Dynamic Properties ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Vibration Transmission ◽  
Auxetic Structures ◽  
Negative Poisson's Ratio

The auxetic lattices are structures, which have the negative Poisson’s ratio. When material has negative Poisson’s ratio, has also auxetic properties - during process of stretching, are made wider and during compressing are made narrower. This structures are cellular and negative Poisson’s ratio is depending on the geometry of single auxetic cell. When geometry of the cell is slightly changed also Poisson’s ratio is different. Auxetics have attracted attention of researchers because of their superior dynamic properties. The lattice auxetic structures at one of their natural frequencies exhibit the deformed geometry. It’s can be exploit as resonance to optimization of the power required for the occurrence localized deformations. The dynamic behavior of auxetic and their transmission of the vibration, which is circumscribed by the parameter VTL (Vibration Transmission Loss) will be analyzed in this article.

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