Nonlinear Analysis of the In-Plane Young’s Moduli of Two-Dimensional Cellular Materials with Negative Poisson’s Ratios

2007 ◽  
Vol 334-335 ◽  
pp. 157-160
Author(s):  
Hui Wan ◽  
Zhen Yu Hu ◽  
Wu Jun Bao ◽  
Guo Ming Hu
Keyword(s):  
Large Deflection ◽  
Small Deformation ◽  
Small Strain ◽  
Cellular Materials ◽  
Deformation Model ◽  
Two Dimensional ◽  
Young’S Moduli ◽  
Incomplete Elliptic Integrals ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

This study deals with the in-plane Young’s moduli of two-dimensional auxetic cellular materials with negative Poisson’s ratios. The in-plane Young’s moduli of these cellular materials are theoretically analyzed, and calculated from the cell member bending with large deflection. Expressions for the in-plane Young’s moduli of the above-mentioned cellular materials are given by incomplete elliptic integrals. It is found that the in-plane Young’s moduli of two-dimensional cellular materials with negative Poisson’s ratios depend both on the geometry of the cell, and on the induced strain of these cellular materials. The in-plane Young’s moduli are no longer constants at large deformation. But at the limit of small strain, they converge to the results predicted by the small deformation model of flexure.

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...

Multilayer Composite Materials with Non-Usual Poisson's Ratios

2007 ◽  
Vol 555 ◽  
pp. 545-552 ◽  
Author(s):  
E.H. Harkati ◽  
Z. Azari ◽  
P. Jodin ◽  
A. Bezazi
Keyword(s):  
Composite Material ◽  
Composite Materials ◽  
Poisson’S Ratio ◽  
Cellular Materials ◽  
Poisson's Ratio ◽  
Multilayer Composite ◽  
Computer Programme ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

Most of usual materials exhibit Poisson's ratio comprised between 0 and 0.5. But, for some kind of cellular materials, or for some stacking sequences of unidirectional plies, a composite material can exhibit negative or greater than 0.5 Poisson's ratios. In this paper, a study of different stacking sequences such as [±β/±θ]s plies made from highly anisotropic fibre pre-preg is presented. A special computer programme has been developed for this purpose. Eighteen stacking sequences, including the [±θ] ones, have been computed. The results show that at least one of Poisson's ratios varies between -0.8 to +0.4. Such kind of materials may find applications for particular cases, as their strength is significantly increased by this phenomenon.

First-principles study on the structural, elastic and electronic properties of the four Si3Sb4 compounds

2019 ◽  
Vol 33 (05) ◽  
pp. 1950047
Author(s):  
Ruike Yang ◽  
Bao Chai ◽  
Qun Wei ◽  
Minhua Xue ◽  
Ye Zhou
Keyword(s):  
Electronic Properties ◽  
First Principles ◽  
Density Functional ◽  
Phonon Dispersion ◽  
Elastic Anisotropy ◽  
Functional Theory ◽  
Shear Moduli ◽  
Young’S Moduli ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

For novel [Formula: see text]-Si3Sb4, pseudocubic-Si3Sb4, cubic-Si3Sb4 and [Formula: see text]-Si3Sb4, the structural, elastic and electronic properties are investigated using first-principles density functional theory (DFT). The elastic constants and phonon dispersion spectra show that they are mechanically and dynamically stable. The bulk moduli, shear moduli, Young’s moduli, Poisson’s ratios and Pugh ratios for the four compounds have been calculated. The bulk moduli indicate that the bond strength of [Formula: see text]-Si3Sb4 is stronger than others. The values of the Poisson’s ratios and Pugh ratios show that pseudocubic-Si3Sb4 is the stiffest among the four Si3Sb4 compounds. Tetragonal Si3Sb4 are more brittle than cubic Si3Sb4. For the four Si3Sb4 compounds, the elastic anisotropies are analyzed via the anisotropic indexes and the 3D surface constructions. The [Formula: see text]-Si3Sb4 elastic anisotropy is stronger than others and the [Formula: see text]-Si3Sb4 is weaker than others. The calculated band structures show that they exhibit metallic features. The results of their TDOS show that there are many similarities. The peaks of TDOS are derived from the contributions of Si “s”, Si “p”, Sb “s” and Sb “p” states.

Two-dimensional ferroelasticity and negative Poisson’s ratios in monolayer YbX (X=S, Se, Te)

2021 ◽  
Author(s):  
Qingwen Lan ◽  
Changpeng Chen
Keyword(s):  
First Principles ◽  
Two Dimensional ◽  
First Principles Calculations ◽  
Two Dimensional Materials ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

Two-dimensional ferroelastic materials and two-dimensional materials with negative Poisson’s ratios have attracted great interest. Here, using first-principles calculations, we reveal the materials—monolayer YbX (X=S, Se, Te) that harbors both ferroelasticity...

scholarly journals Moisture-dependent orthotropic tension-compression asymmetry of wood

Holzforschung ◽  
2013 ◽  
Vol 67 (4) ◽  
pp. 395-404 ◽  
Author(s):  
Tomasz Ozyhar ◽  
Stefan Hering ◽  
Peter Niemz
Keyword(s):  
Yield Stress ◽  
Stress Ratio ◽  
Beech Wood ◽  
Strength Parameters ◽  
Young’S Moduli ◽  
Strength Asymmetry ◽  
Poisson's Ratios ◽  
Tension Compression Asymmetry ◽  
Poisson’S Ratios ◽  
Tangential Directions

Abstract The influence of moisture content (MC) on the tension-compression (Te-Co) asymmetry of beech wood has been examined. The elastic and strength parameters, including Te and Co Young’s moduli, Poisson’s ratios, and ultimate and yield stress values, were determined and compared in terms of different MCs for all orthotropic directions. The results reveal a distinctive Te-Co strength asymmetry with a moisture dependency that is visualized clearly by the Te to Co yield stress ratio. The Te-Co asymmetry is further shown by the inequality of the elastic properties, known as the “bimodular behavior”. The latter is proven for the Young’s moduli values in the radial and tangential directions and for individual Poisson’s ratios. Although the bimodularity of the Young’s moduli is significant at low MC levels, there is no evidence of moisture dependency on the Te-Co asymmetry of the Poisson’s ratios.

Compliant Cellular Materials With Elliptical Holes for Extremely High Positive and Negative Poisson's Ratios

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Jaehong Lee ◽  
Kwangwon Kim ◽  
Jaehyung Ju ◽  
Doo-Man Kim
Keyword(s):  
Poisson’S Ratio ◽  
Longitudinal Direction ◽  
Materials Design ◽  
Cellular Materials ◽  
Poisson's Ratio ◽  
Yield Strain ◽  
Large Rotation ◽  
Elliptical Holes ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

Cellular materials' two important properties—structure and mechanism—can be selectively used for materials design; in particular, they are used to determine the modulus and yield strain. The objective of this study is to gain a better understanding of these two properties and to explore the synthesis of compliant cellular materials (CCMs) with compliant porous structures (CPSs) generated from modified hexagonal honeycombs. An in-plane constitutive CCM model with CPSs of elliptical holes is constructed using the strain energy method, which uses the deformation of hinges around holes and the rotation of links. A finite element (FE) based simulation is conducted to validate the analytical model. The moduli and yield strains of the CCMs with an aluminum alloy are about 4.42 GPa and 0.57% in one direction and about 2.14 MPa and 20.9% in the other direction. CCMs have extremely high positive and negative Poisson's ratios (NPRs) (νxy* ∼ ±40) due to the large rotation of the link member in the transverse direction caused by an input displacement in the longitudinal direction. A parametric study of CCMs with varying flexure hinge geometries using different porous shapes shows that the hinge shape can control the yield strength and strain but does not affect Poisson's ratio which is mainly influenced by rotation of the link members. The synthesized CPSs can also be used to design a new CCM with a Poisson's ratio of zero using a puzzle-piece CPS assembly. This paper demonstrates that compliant mesostructures can be used for next generation materials design in tailoring mechanical properties such as moduli, strength, strain, and Poisson's ratios.

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