The effect of anisotropy on the Young's moduli and Poisson's ratios of shales

2012 ◽  
Vol 61 (2) ◽  
pp. 416-426 ◽  
Author(s):  
Colin M. Sayers
Keyword(s):  
Young’S Moduli ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

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.

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 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.

scholarly journals Time dependence of the orthotropic compression Young’s moduli and Poisson’s ratios of Chinese fir wood

Holzforschung ◽  
2016 ◽  
Vol 70 (11) ◽  
pp. 1093-1101 ◽  
Author(s):  
Jiali Jiang ◽  
Bachtiar Erik Valentine ◽  
Jianxiong Lu ◽  
Peter Niemz
Keyword(s):  
Creep Strain ◽  
Viscoelastic Behavior ◽  
Chinese Fir ◽  
Image Correlation ◽  
Time Dependency ◽  
Compliance Matrix ◽  
Young’S Moduli ◽  
The Individual ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

Abstract The time dependency of the orthotropic compliance for Chinese fir wood [Cunninghamia lanceolata (Lamb.) Hook] has been investigated by performing compressive creep experiments in all orthotropic directions. Time evolution of the creep strain in the axial and lateral directions was recorded by means of the digital image correlation (DIC) technique, to determine the diagonal and nondiagonal elements of the viscoelastic compliance matrix. The results reveal the significant influence of time on the mechanical behavior. The orthotropic nature of the viscoelastic compliance is highlighted by the different time dependency of the Young’s moduli and the Poisson’s ratios obtained for the individual directions. Differences among the time-dependent stress-strain relationship determined at the 25, 50, and 75% stress levels indicate that the viscoelastic behavior of wood is also load-dependent. A Poisson’s ratio values, which are increasing with time in νLR, νLT, νRT, νTR, and decreasing in νRL and νTL, demonstrate that the creep strain is influenced by loading directions. The substantially different time dependency of the nondiagonal elements of the compliance matrix further reveals the orthotropic compliance asymmetry and emphasizes the complexity of the viscoelastic character of wood.

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