Theoretical Modeling on the Deformation Behavior of Auxetic Tubular Braid Made from Modified Circular Braiding Technique

Jiang, Ning; Chen, Yu; Hu, Hong

doi:10.1002/pssb.201900173

Cited by 12 publications

(10 citation statements)

References 28 publications

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“…Different from traditional Helical Auxetic Yarns (HAYs), the core yarn in the BAYs was not completely stretched at the initial state, but had a little bend itself, which was equivalent to a pre-stretched state. Different from the BAYs in Jiang et al 21 and Chen et al 22 the diameter of the BAYs was smaller, which made its application value more extensive. In the process of stretching, the buckling of the core yarn gradually increased, and the rigid yarn gradually tried to change from bending to the stretching state.…”

Section: Resultsmentioning

confidence: 86%

Fabrication and characterization of braided auxetic yarns based on a high-speed braiding machine

Liu

et al. 2022

Textile Research Journal

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In recent years, three kinds of auxetic yarns have mainly been developed, namely helical auxetic yarns based on the ring spinning system and the hollow spindle system and braided auxetic yarns based on the braiding system. However, these auxetic yarns have some drawbacks, such as an unstable structure or no obvious auxetic effect. In this paper, auxetic yarns were successfully braided by wrap filaments and a core filament based on a braiding system, which overcame the slippage problem in the traditional helical yarn structure. Yarns were spun by different structural parameters of the core filament, the wrap filaments and braiding filament, including the diameter ratio, braiding speed and different numbers of wrap filaments. The results showed that all parameters have an impact on the Poisson’s ratio of auxetic yarns and, in addition, the braided auxetic yarns can cause the yarns to be in the pre-stretching state; once the stretching effect occurs, the Poisson's ratio will directly change from a negative value. Since the new auxetic yarns were produced using a high-speed braiding machine and filaments, this would pave the way for their mass production. This provides a certain research basis for mass production of the stable auxetic yarn structure, and based on the realization of the pre-stretching state, it also provides more possibilities for future research.

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Section: Resultsmentioning

confidence: 86%

Fabrication and characterization of braided auxetic yarns based on a high-speed braiding machine

Liu

et al. 2022

Textile Research Journal

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“…Akin to a HAY, under tensile deformation the radius of the metal helix decreases, and the core deforms into a helical configuration to accommodate the compression (Figure 3c, II-IV). For given wrap and core materials, the main geometric parameter controlling mechanical properties of HAYs is the initial angle α 0 between the helical wire and the cross section of the fiber (wrapping angle), [56][57][58][59] which is given by:…”

Section: D Helical Electrodesmentioning

confidence: 99%

Thermally Drawn Highly Conductive Fibers with Controlled Elasticity

et al. 2022

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bare interconnects with regular yarns or attaching devices to the surface of fabrics, encapsulating both electrodes and devices within the cladding of a single fiber confers mechanical and moisture protection while allowing increased electrode and device density. However achieving device functionality at the single fiber level requires high electrical conductivity (>10 6 S m −1 ) without compromising elasticity. It is important to emphasize that elasticity is necessary for the fiber to withstand the fabric construction process in weaving [10] and knitting, [11] and also for daily use. [12] Studies have explored polymer nanocomposites, conductive polymers [13][14][15] and liquid metals, [16,17] to couple conductivity and elasticity at the fiber level. Despite these recent advances, the challenge of creating a fiber that is highly elastic and highly conductive remains largely unmet.We note that the structure of a fabric, in particular in knits, is routinely used to impart elasticity on the fabric level. [12,18] Similarly, structurebased elasticity has been leveraged extensively in stretchable electronics, [19,20] where thin metal traces in shapes of serpentines, [21][22][23][24] wrinkles, [25][26][27] and helices [24,28,29] have been attached to, or embedded in an elastomeric matrix. Upon stretching, the metal deforms through bending, allowing for tens of percent of reversible strain without impairing the conductivity.Electronic fabrics necessitate both electrical conductivity and, like any textile, elastic recovery. Achieving both requirements on the scale of a single fiber remains an unmet need. Here, two approaches for achieving conductive fibers (10 7 S m −1 ) reaching 50% elongation while maintaining minimal change in resistance (<0.5%) in embedded metallic electrodes are introduced. The first approach involves inducing a buckling instability in a metal microwire within a cavity of a thermally drawn elastomer fiber. The second approach relies on twisting an elastomer fiber to yield helical metal electrodes embedded in a stretchable yarn. The scalability of both approaches is illustrated in apparatuses for continuous buckling and twisting that yield tens of meters of elastic conducting fibers. Through experimental and analytical methods, it is elucidated how geometric parameters, such as buckling pre-strain and helical angle, as well as materials choice, control not only the fiber's elasticity but also its Young's modulus. Links between mechanical and electrical properties are exposed. The resulting fibers are used to construct elastic fabrics that contain diodes, by weaving and knitting, thus demonstrating the scalable fabrication of conformable and stretchable antennas that support optical data transmission.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202201081.

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“…Hundreds (if not thousands) of papers have been devoted to matching the values of geometric and/or material parameters of microstructures in such a way as to enable the control of the effective Poisson's ratio values ν H in the full range of its permissible values, that is, −1 ≤ ν H ≤ 1 and −1 ≤ ν H ≤ 0.5 for 2D and 3D elastic, isotropic bodies, respectively—see for example, the selected and the most current studies. [ 24–60 ] It is worth emphasizing that a clear and simple proving of the earlier permissible ranges of Poisson's ratio for isotropic material was disclosed by Wojciechowski [ 24 ] published almost 20 years ago. More than 30 years ago, the same author showed that simple hexagonal units (hard cyclic hexamers) spontaneously form an auxetic isotropic crystal in two dimensions (see the study by Wojciechowski [ 25 ] ).…”

Section: Introductionmentioning

confidence: 99%

Bending‐Free Lattices as Underlying Optimal Isotropic Microstructures of the Least‐Compliant 2D Elastic Bodies

Czarnecki

Łukasiak

2021

Physica Status Solidi (b)

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This study puts forward a method of reconstruction of the suboptimal isotropic truss microstructures for the known distribution of Young's modulus and Poisson's ratio predicted by the Isotropic Material Design (IMD) method of minimizing the compliance (maximizing the stiffness) of a 2D elastic body. The varying underlying microstructures corresponding to the optimal designs are recovered by matching the values of the optimal elastic moduli with the values of the effective moduli of the representative volume elements (RVE) computed by the asymptotic homogenization method. The used hexagonal shape of the RVE with its specific internal symmetry provides the assumed isotropy of the periodic body. Hexagonal periodic cells are made up of 3 or 12 pin‐jointed families of bars with different stiffness characteristics. Combining these families into two or three groups with identical bar stiffnesses in a group allows for the exact reproduction of Poisson's ratio for each point of the body. The ability to model an auxetic behavior within the subdomains where the optimal Poisson's ratio assumes negative values is also shown. The effective value of the Young's modulus is scaled independently of the value of the effective Poisson's ratio by selecting the cross section of the bars in the group.

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Theoretical Modeling on the Deformation Behavior of Auxetic Tubular Braid Made from Modified Circular Braiding Technique

Cited by 12 publications

References 28 publications

Fabrication and characterization of braided auxetic yarns based on a high-speed braiding machine

Fabrication and characterization of braided auxetic yarns based on a high-speed braiding machine

Thermally Drawn Highly Conductive Fibers with Controlled Elasticity

Bending‐Free Lattices as Underlying Optimal Isotropic Microstructures of the Least‐Compliant 2D Elastic Bodies

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