scholarly journals Large-scale manufacturing of helical auxetic yarns using a novel semi-coextrusion process

2017 ◽  
Vol 88 (22) ◽  
pp. 2590-2601 ◽  
Author(s):  
Guanhua Zhang ◽  
Oana R Ghita ◽  
Congping Lin ◽  
Kenneth E Evans
Keyword(s):  
Poisson’S Ratio ◽  
Large Scale ◽  
Cost Effective ◽  
Extrusion Process ◽  
Poisson's Ratio ◽  
Ratio Analysis ◽  
Analysis Method ◽  
Spun Yarns ◽  
Wrap Angle ◽  
Manufacturing Parameters

This paper introduces a novel extrusion process for manufacturing helical auxetic yarn (HAY). A range of semi-coextruded HAYs have been manufactured in a cost-effective, consistent and readily usable form. The semi-coextruded HAYs were compared to the conventional spun yarns in terms of tensile properties and auxetic behavior. The results show the presence of the auxetic effect in newly fabricated semi-coextruded HAYs. Similar to the traditional spun HAYs, the new HAYs are sensitive to parameters such as the initial wrap angle, the core/wrap diameter ratio and component moduli. Importantly, a few new manufacturing parameters have been identified for tailoring the auxetic behavior of the semi-coextruded HAYs. The semi-coextruded HAYs are auxetic when an instantaneous true Poisson’s ratio analysis method is applied. The semi-coextruded HAYs give a larger maximum negative Poisson’s ratio than the conventional HAYs due to the advantages of the pre-formed helical wrap structure.

A study of tubular braided structure with negative Poisson’s ratio behavior

2017 ◽  
Vol 88 (24) ◽  
pp. 2810-2824 ◽  
Author(s):  
Ning Jiang ◽  
Hong Hu
Keyword(s):  
Poisson’S Ratio ◽  
Structural Parameters ◽  
Uniaxial Extension ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
Yarn Diameter ◽  
Wrap Angle ◽  
Negative Poisson's Ratio ◽  
Braided Structure ◽  
Braiding Angle

Textile structures with negative Poisson’s ratio (PR) behavior are called auxetic textile structures. They have received increasing attention in recent years and have been designed and fabricated through spinning, knitting, weaving and non-woven methods. However, auxetic textile structures fabricated using braiding method have not been reported so far. This paper reported a novel type of auxetic braided structure based on a helical structural arrangement. The geometry of the structure and its deformation mechanism were first introduced and described. Then a special manufacturing process was developed by the modification of commonly used tubular braiding technology. Various auxetic braids were fabricated with different structural parameters and yarns and tested under uniaxial extension conditions. The results showed that all manufactured braids exhibited high negative PR behavior and maintained this behavior until the fracture of the component wrap yarn. Among three structural parameters discussed, namely wrap angle, braiding angle and braiding yarn diameter, the wrap angle had more effects on the tensile properties of auxetic braided structure than the other two parameters. The success of fabricating auxetic braids with commercially available yarns in this study provides an alternative way to manufacture auxetics from positive PR materials.

Investigation into the Dynamic Fracture Properties of Large Scale Functionally Graded Materials

2006 ◽  
Vol 324-325 ◽  
pp. 239-242 ◽  
Author(s):  
Xiao Bin Yang ◽  
Zhuo Zhuang ◽  
Xue Feng Yao
Keyword(s):  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Large Scale ◽  
Young's Modulus ◽  
Mass Density ◽  
Poisson's Ratio ◽  
Constant Mass ◽  
Functionally Gradient Materials ◽  
Gradient Materials ◽  
Functionally Gradient

A crack propagation perpendicular to gradient in a large scale functionally gradient materials, which has (1) a linear variation of Young’s modulus with a constant mass density and Poisson’s ratio, and (2) a exponential variation of Young’s modulus with a constant mass density and Poisson’s ratio, is modelled by finite element methods. Based on the experimental result of large scale functionally gradient materials, the dynamic propagation process of the FGMs is modelled and the dynamic parameters, like the energy release rate and crack tip opening angle, are calculated through a generation phase.

Poisson’s ratio and porosity of carbon nanotube dry-spun yarns

Carbon ◽  
2010 ◽  
Vol 48 (10) ◽  
pp. 2802-2811 ◽  
Author(s):  
Menghe Miao ◽  
Jill McDonnell ◽  
Lucy Vuckovic ◽  
Stephen C. Hawkins
Keyword(s):  
Carbon Nanotube ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Spun Yarns

Accuracy of finite‐difference and finite‐element modeling of the scalar and elastic wave equations

Geophysics ◽  
1984 ◽  
Vol 49 (5) ◽  
pp. 533-549 ◽  
Author(s):  
Kurt J. Marfurt
Keyword(s):  
Finite Element ◽  
Finite Difference ◽  
Elastic Wave ◽  
Frequency Domain ◽  
Poisson’S Ratio ◽  
Wave Equations ◽  
Cost Effective ◽  
Poisson's Ratio ◽  
Solution Technique ◽  
Elastic Wave Equations

Numerical solutions of the scalar and elastic wave equations have greatly aided geophysicists in both forward modeling and migration of seismic wave fields in complicated geologic media, and they promise to be invaluable in solving the full inverse problem. This paper quantitatively compares finite‐difference and finite‐element solutions of the scalar and elastic hyperbolic wave equations for the most popular implicit and explicit time‐domain and frequency‐domain techniques. In addition to versatility and ease of implementation, it is imperative that one choose the most cost effective solution technique for a fixed degree of accuracy. To be of value, a solution technique must be able to minimize (1) numerical attenuation or amplification, (2) polarization errors, (3) numerical anisotropy, (4) errors in phase and group velocities, (5) extraneous numerical (parasitic) modes, (6) numerical diffraction and scattering, and (7) errors and transmission coefficients. This paper shows that in homogeneous media the explicit finite‐element and finite‐difference schemes are comparable when solving the scalar wave equation and when solving the elastic wave equations with Poisson’s ratio less than 0.3. Finite‐elements are superior to finite‐differences when modeling elastic media with Poisson’s ratio between 0.3 and 0.45. For both the scalar and elastic equations, the more costly implicit time integration schemes such as the Newmark scheme are inferior to the explicit central‐differences scheme, since time steps surpassing the Courant condition yield stable but highly inaccurate results. Frequency‐domain finite‐element solutions employing a weighted average of consistent and lumped masses yield the most accurate results, and they promise to be the most cost‐effective method for CDP, well log, and interactive modeling.

scholarly journals Continuous measurement of apparent Poisson’s ratio for yarn based on omni-directional diameters

2016 ◽  
Vol 87 (6) ◽  
pp. 739-746 ◽  
Author(s):  
Masayuki Takatera ◽  
Tamotsu Arichi ◽  
Julie Peiffer ◽  
Chunhong Zhu ◽  
KyoungOk Kim
Keyword(s):  
Poisson’S Ratio ◽  
Longitudinal Strain ◽  
Poisson's Ratio ◽  
Transverse Strain ◽  
Tensile Tester ◽  
Fiber Packing Density ◽  
Spun Yarns ◽  
The Mean ◽  
Transverse Strains ◽  
The Relationship

We proposed a new method for measuring apparent Poisson’s ratio for yarn and developed a new tensile tester equipped with a digital micrometer that can measure the omni-directional diameter of the yarn annularly while the yarn is elongated. Values of apparent Poisson’s ratio were obtained from the longitudinal and transverse strains continuously. The mean diameter measured omni-directionally was used to calculate the transverse strain for each longitudinal strain. We tested five spun yarns, one monofilament yarn and two filament yarns and obtained values of apparent Poisson’s ratio against longitudinal strain for all samples. Apparent Poisson’s ratio was not constant for spun and filament yarns, while it was constant for monofilament yarn. When the longitudinal strain was low, apparent Poisson’s ratios of ring spun yarns and filament yarns were large, owing to the fiber packing density. As the longitudinal strain increased, apparent Poisson’s ratio gradually decreased. Furthermore, we approximated the relationship between apparent Poisson’s ratio and the longitudinal strain using a power function. The apparent Poisson values can be used in the simulation of fabrics.

Enhancing the mechanical properties of virgin and damaged jute/polypropylene hybrid nonwoven geotextiles via mild alkali treatment of jute fibers

2018 ◽  
Vol 88 (18) ◽  
pp. 2132-2140 ◽  
Author(s):  
Amit Rawal ◽  
Ayush Paharia ◽  
Vijay Kumar
Keyword(s):  
Mechanical Properties ◽  
Poisson’S Ratio ◽  
Sodium Hydroxide Solution ◽  
Alkali Treatment ◽  
Natural Fibers ◽  
Physical And Mechanical Properties ◽  
Cost Effective ◽  
Poisson's Ratio ◽  
Minimal Amount ◽  
Jute Fibers

Nonwoven geotextiles made from hybridization of natural and synthetic fibers can potentially offer distinct advantages in terms of uniformity and improved mechanical properties. To further enhance the mechanical properties of hybrid nonwoven geotextiles, natural fibers such as jute must be treated with a minimal amount of alkali, such that the treatment process becomes scalable, cost-effective and environmentally friendly. Herein, we report a comparative analysis of physical and mechanical properties between the corresponding samples of untreated (UT) jute/polypropylene (PP) and mild alkali-treated (MAT) jute/PP nonwoven geotextiles in both virgin and damaged conditions. The constituent jute fibers were treated with 0.5 wt.% of sodium hydroxide solution under ambient temperature conditions for 24 h duration. Such mild treatment of jute fibers with alkali solution resulted in considerable improvement in the mechanical properties of MAT jute/PP nonwoven geotextiles corresponding to the sets of UT jute/PP nonwoven geotextiles. Various types of damage, including circular holes, horizontal cuts, vertical cuts and inclined cuts at an angle of 45°, were artificially induced in hybrid nonwoven geotextiles to investigate the reduction in tensile properties. Further, the Poisson's ratio in virgin and damaged states was determined to make a comparison between the UT and MAT jute/PP nonwoven geotextiles. In general, lower Poisson's ratio values were observed for mechanically damaged MAT jute/PP nonwoven geotextiles corresponding to the samples of UT jute/PP nonwoven geotextiles. Surprisingly, the vertical cuts induced in MAT jute/PP nonwoven geotextiles yielded tensile strength comparable to that of virgin samples.

Development of helical auxetic yarn with negative Poisson’s ratio by combinations of different materials and wrapping angle

2020 ◽  
pp. 152808372094111
Author(s):  
Tehseen Ullah ◽  
Sheraz Ahmad ◽  
Yasir Nawab
Keyword(s):  
Poisson’S Ratio ◽  
Transverse Direction ◽  
Poisson Ratio ◽  
Longitudinal Direction ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
The Core ◽  
Inverse Effect ◽  
Wrap Angle ◽  
Negative Poisson's Ratio

Auxetic materials have negative Poisson ratio which has a multiple ranges of functional applications. The helical auxetic yarn was successfully developed through direct twist system by using core and wrap yarn or filament, which shows Auxeticity when the HAY is stretched in longitudinal direction in response it expand in transverse direction, Helical Auxetic Yarns were developed using various parameters of the core and warp filament, these parameters are wrapping angle (Twist per meter), diameter ratio, and modulus ratio. The strength of Helical yarn was characterized using single yarn strength and Image J software was used for the calculation of poisson’s ratio. According to test results, it is concluded that the core filament of helical auxetic yarn increased its thickness in transverse direction under stress, and a considerable negative poisson’s ratio was calculated. The values of negative poisson’s ratio described that the auxeticity had a direct relation with core filament thickness or diameter and inversely proportional to the linear density of wrap filament, in case of the wrap angle the auxeticity of HAY yarn had an inverse effect with wrap angle. Kevlar/polypropylene combination sample showed maximum auxeticity at a 15-degree angle while Kevlar/nylon combination sample showed minimum auxeticity at a 25-degree wrap angle.

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