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.

scholarly journals Modelling the elastic mechanical properties of bioactive glass-derived scaffolds

2020 ◽  
Vol 6 (1) ◽  
pp. 50-56
Author(s):  
Francesco Baino ◽  
Elisa Fiume
Keyword(s):  
Elastic Properties ◽  
Poisson’S Ratio ◽  
Mechanical Performance ◽  
Solid Material ◽  
Poisson's Ratio ◽  
Predictive Capability ◽  
Shear Moduli ◽  
Wide Range ◽  
Constitutive Parameters ◽  
The Relationship

AbstractPorosity is known to play a pivotal role in dictating the functional properties of biomedical scaffolds, with special reference to mechanical performance. While compressive strength is relatively easy to be experimentally assessed even for brittle ceramic and glass foams, elastic properties are much more difficult to be reliably estimated. Therefore, describing and, hence, predicting the relationship between porosity and elastic properties based only on the constitutive parameters of the solid material is still a challenge. In this work, we quantitatively compare the predictive capability of a set of different models in describing, over a wide range of porosity, the elastic modulus (7 models), shear modulus (3 models) and Poisson’s ratio (7 models) of bioactive silicate glass-derived scaffolds produced by foam replication. For these types of biomedical materials, the porosity dependence of elastic and shear moduli follows a second-order power-law approximation, whereas the relationship between porosity and Poisson’s ratio is well fitted by a linear equation.

Finite element analysis of flexible functionally graded beams with variable Poisson’s ratio

2016 ◽  
Vol 33 (8) ◽  
pp. 2421-2447 ◽  
Author(s):  
João Paulo Pascon
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Poisson’S Ratio ◽  
Scientific Literature ◽  
Functionally Graded ◽  
Poisson's Ratio ◽  
Transverse Strain ◽  
Thickness Direction ◽  
Element Analysis ◽  
Content Type

Purpose The purpose of this paper is to deal with large deformation analysis of plane beams composed of functionally graded (FG) elastic material with a variable Poisson’s ratio. Design/methodology/approach The material is assumed to be linear elastic, with a Poisson’s ratio varying according to a power law along the thickness direction. The finite element used is a plane beam of any-order of approximation along the axis, and with four transverse enrichment schemes, which can describe constant, linear, quadratic and cubic variation of the strain along the thickness direction. Regarding the constitutive law, five materials are adopted: two homogeneous limiting cases, and three intermediate FG cases. The effect of both finite element kinematics and distribution of Poisson’s ratio on the mechanical response of a cantilever is investigated. Findings In accordance with the scientific literature, the second scheme, in which the transverse strain is linearly variable, is sufficient for homogeneous long (or thin) beams under bending. However, for FG short (or moderate thick) beams, the third scheme, in which the transverse strain variation is quadratic, is needed for a reliable strain or stress distribution. Originality/value In the scientific literature, there are several studies regarding nonlinear analysis of functionally graded materials (FGMs) via finite elements, analysis of FGMs with constant Poisson’s ratio, and geometrically linear problems with gradually variable Poisson’s ratio. However, very few deal with finite element analysis of flexible beams with gradually variable Poisson’s ratio. In the present study, a reliable formulation for such beams is presented.

Study on a New Testing Method of the Elastic Modulus and Poisson's Ratio by Using Brazilian Disk Test

2013 ◽  
Vol 347-350 ◽  
pp. 1199-1202
Author(s):  
Fei Wu ◽  
Shi Ming Dong
Keyword(s):  
Elastic Modulus ◽  
Poisson’S Ratio ◽  
Vertical Direction ◽  
Test Method ◽  
Poisson's Ratio ◽  
Theoretical Formula ◽  
Brazilian Disk ◽  
Total Displacement ◽  
The Relationship ◽  
Poissons Ratio

In order to develop a new test method of the elastic modulus and Poissons ratio, based on the theoretical analysis of the Brazilian disk diametrically loaded by a pair of forces, the relationship is obtained between the total displacement of one point on the vertical direction of the load line and the applied force as well as the elastic modulus and Poissons ratio. The strain gauges with different length are used to measure the displacement of the corresponding point, and then the displacement is employed to calculate the elastic modulus and Poisson's ratio by using the theoretical formula. The proposed method can provide a new approach to estimate the elastic modulus and Poissons ratio by using Brazilian disk splitting tests.

A Novel Constitutive Model for Concrete under Uniaxial Compression

2010 ◽  
Vol 650 ◽  
pp. 47-55 ◽  
Author(s):  
Jin Long Pan ◽  
Jia Jia Zhou ◽  
Zong Jin Li ◽  
Christopher K.Y. Leung
Keyword(s):  
Constitutive Model ◽  
Uniaxial Compression ◽  
Poisson’S Ratio ◽  
Longitudinal Strain ◽  
Polynomial Function ◽  
Poisson's Ratio ◽  
Test Results ◽  
Proposed Model ◽  
Order Polynomial

In this paper, a novel constitutive model of concrete has been proposed by introducing a new parameter, namely, cracking Poisson’s ratio (νcr), to account for the effect of localization due to cracking. By fitting the curve between the dimensionless strain (ε/εpr) and cracking Poisson’s ratio (νcr), νcr can be expressed as an 3rd order polynomial function of dimensionless longitudinal strain (ε/εpr). The constitutive model for the softening regime can then be proposed with the parameters of dimensionless strain and cracking Poisson’s ratio. Finally, Validity of the proposed model is verified by the test results of cylinder specimens of C30.

The Effect of Fiber Microstructure on the Observed Poisson’s Ratio of Tendon and Ligament Tissue

2008 ◽  
Author(s):  
Shawn P. Reese ◽  
Steve A. Maas ◽  
Heath A. Henninger ◽  
Jeffrey A. Weiss
Keyword(s):  
Poisson’S Ratio ◽  
Collagen Fiber ◽  
Poisson's Ratio ◽  
Fiber Direction ◽  
Exact Nature ◽  
Tendon Tissue ◽  
Element Analysis ◽  
The Relationship ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

During tensile testing along the predominant collagen fiber direction, ligament and tendon tissue exhibit large Poisson’s ratios ranging from 1.3 in capsular ligament to 2.98 in flexor tendon [1][2]. Although the microstructure of these tissues (especially fiber crimp) has been characterized, the relationship between microstructure and Poisson’s ratio is relatively unexplored. There has been debate regarding the exact nature of the characteristic crimp within tendon fibers, however the two views most present in the literature are that of planar crimp and helical crimp. The aim of this study was to perform a finite element analysis on prototypical models of fibril bundles for both forms of crimp under tensile loading conditions. It was hypothesized that planar crimp alone would be insufficient for generating large Poisson’s ratios, and that some other microstructure (such as a helix) would be required.

scholarly journals First-Principle Studies on the Mechanical and Electronic Properties of AlxNiyZrz (x = 1~3, y = 1~2, z = 1~6) Alloy under Pressure

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4972
Author(s):  
Xiaoli Yuan ◽  
Weikang Li ◽  
Peng Wan ◽  
Mi-An Xue
Keyword(s):  
Electronic Properties ◽  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Young's Modulus ◽  
Central Force ◽  
Poisson's Ratio ◽  
Electron Effective Mass ◽  
Superconducting Material ◽  
Pressure Scale ◽  
The Relationship

The elastic and electronic properties of AlxNiyZrz (AlNiZr, Al2NiZr6, AlNi2Zr, and Al5Ni2Zr) under pressure from 0 to 50 GPa have been investigated by using the density function theory (DFT) within the generalized gradient approximation (GGA). The elastic constants Cij (GPa), Shear modulus G (GPa), Bulk modulus B (GPa), Poisson’s ratio σ, Young’s modulus E (GPa), and the ratio of G/B have been studied under a pressure scale to 50 GPa. The relationship between Young’s modulus of AlxNiyZrz is Al5Ni2Zr > AlNiZr > Al2NiZr6 > AlNi2Zr, which indicates that the relationship between the stiffness of AlxNiyZrz is Al5Ni2Zr > AlNiZr > Al2NiZr6 > AlNi2Zr. The conditions are met at 30 and 50 GPa, respectively. What is more, the G/B ratios for AlNiZr, AlNi2Zr, Al2NiZr6, and Al5Ni2Zr classify these materials as brittle under zero pressure, while with the increasing of the pressure the G/B ratios of AlNiZr, AlNi2Zr, Al2NiZr6, and Al5Ni2Zr all become lower, which indicates that the pressure could enhance the brittle properties of these materials. Poisson’s ratio studies show that AlNiZr, AlNi2Zr, and Al2NiZr6 are all a central force, while Al5Ni2Zr is a non-central force pressure scale to 50 GPa. The energy band structure indicates that they are all metal. The relationship between the electrical conductivity of AlxNiyZrz is Al2NiZr6 > Al5Ni2Zr > AlNi2Zr > AlNiZr. What is more, compared with Al5Ni2Zr, AlNi2Zr has a smaller electron effective mass and larger atom delocalization. By exploring the elastic and electronic properties, they are all used as a superconducting material. However, Al5Ni2Zr is the best of them when used as a superconducting material.

An Experimental Method to Determine Poisson’s Ratio in a Small Beam Subject to Seismic Excitation

1997 ◽  
Author(s):  
Roberto Caracciolo ◽  
Alessandro Gasparetto ◽  
Marco Giovagnoni
Keyword(s):  
Experimental Method ◽  
Poisson’S Ratio ◽  
Iterative Procedure ◽  
Master Curve ◽  
Seismic Excitation ◽  
Poisson's Ratio ◽  
Strain Gauges ◽  
Frequency Range ◽  
Different Temperatures ◽  
Transverse Strains

Abstract An experimental method to determine Poisson’s ratio in a small beam subject to seismic excitation is presented. Poisson’s ratio is computed by measuring longitudinal and transverse strains by means of electric strain gauges. A first set of tests is carried out with different materials, and it is observed that the measured Poisson’s ratio decreases with frequency. However, to determine whether the observed decrease is true or it is due to an error caused by the plate effect of the beam, a second set of tests at different temperatures is carried out. Then, by applying the reduced variables method, a unique plot for Poisson’s ratio on a much broader frequency range is obtained, which allows to state that the decrease of Poisson’s ratio is true. An iterative procedure is described, which has been developed to gather the curves at different temperatures in a master curve.

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.

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