First-Principles Study of the Elastic Properties of Hexagonal Phase ScAx (A=H, He)

2013 ◽  
Vol 690-693 ◽  
pp. 1723-1727
Author(s):  
Kai Min Fan ◽  
Li Yang ◽  
Jing Tang ◽  
Qing Qiang Sun ◽  
Xiao Tao Zu
Keyword(s):  
Elastic Modulus ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
First Principles ◽  
Poisson’S Ratio ◽  
Hexagonal Phase ◽  
Poisson's Ratio ◽  
First Principles Calculations ◽  
Charge Densities ◽  
Change Mechanism

First-principles calculations are performed to investigate the Young’s modulus, bulk modulus, shear modulus and Poisson’s ratio of hexagonal phase ScAx(A=H, He), where x=0, 0.0313, 0.125 and 0.25, represent the ratio of interstitial atoms A (A=H, He) to Sc atoms. The influences of hydrogen concentrations and helium concentrations on elastic modulus and Poisson’s ratio of ScAx(A=H, He) have been studied. The results indicate that hydrogen and helium have different effects on the elastic modulus of hexagonal phase scandium. The change mechanism of the Poisson’s ratio with the variation of the x ranging from 0 to 0.25 has also been studied in hexagonal phase ScAx(A=H, He). In addition, the changes in the charge densities of ScAxdue to the presence of hydrogen and helium have been calculated.

scholarly journals The Mechanical Properties and Elastic Anisotropies of Cubic Ni3Al from First Principles Calculations

Crystals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 307 ◽  
Author(s):  
Xinghe Luan ◽  
Hongbo Qin ◽  
Fengmei Liu ◽  
Zongbei Dai ◽  
Yaoyong Yi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
Young’S Modulus ◽  
First Principles ◽  
Poisson’S Ratio ◽  
Density Functional ◽  
Young's Modulus ◽  
Small Deviation ◽  
Poisson's Ratio

Ni3Al-based superalloys have excellent mechanical properties which have been widely used in civilian and military fields. In this study, the mechanical properties of the face-centred cubic structure Ni3Al were investigated by a first principles study based on density functional theory (DFT), and the generalized gradient approximation (GGA) was used as the exchange-correlation function. The bulk modulus, Young’s modulus, shear modulus and Poisson’s ratio of Ni3Al polycrystal were calculated by Voigt-Reuss approximation method, which are in good agreement with the existing experimental values. Moreover, directional dependences of bulk modulus, Young’s modulus, shear modulus and Poisson’s ratio of Ni3Al single crystal were explored. In addition, the thermodynamic properties (e.g., Debye temperature) of Ni3Al were investigated based on the calculated elastic constants, indicating an improved accuracy in this study, verified with a small deviation from the previous experimental value.

Structural, Mechanical and Electronic Properties of o-BC6N

2019 ◽  
Vol 74 (11) ◽  
pp. 1037-1042
Author(s):  
Ruijiao Jiang ◽  
Jianguo Zhang ◽  
Qun Wei ◽  
Minhua Xue
Keyword(s):  
High Pressure ◽  
Electronic Structure ◽  
Shear Modulus ◽  
Electronic Properties ◽  
First Principles ◽  
Poisson’S Ratio ◽  
Structure Study ◽  
Poisson's Ratio ◽  
First Principles Calculations ◽  
Large Anisotropy

AbstractThe mechanical and electronic properties of o-BC6N are studied by using first-principles calculations. The anisotropy studies of Young’s modulus, shear modulus and Poisson’s ratio show that o-BC6N exhibits a large anisotropy. Electronic structure study shows that o-BC6N presents metallicity under the conditions of zero and high pressure.

scholarly journals Effect of Temperature on Formaldehyde Diffusion in Cellulose Amorphous Region: A Simulation Study

BioResources ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. 3200-3213
Author(s):  
Wei Wang ◽  
Yancai Cao ◽  
Liyue Sun ◽  
Mingshuai Wu
Keyword(s):  
Shear Modulus ◽  
Bulk Modulus ◽  
Poisson’S Ratio ◽  
Amorphous Region ◽  
Poisson's Ratio ◽  
Effect Of Temperature ◽  
External Temperature ◽  
Practical Applications ◽  
Region Model ◽  
Materials Studio

A formaldehyde-cellulose amorphous region model at the micro-level was established using the molecular dynamics software Materials Studio to simulate the change of cellulose and formaldehyde molecules in an external temperature field. The diffusion coefficients of formaldehyde molecules increased as the temperature increased. Moreover, the total number of hydrogen bonds decreased, and the interaction energy in the formaldehyde-cellulose model was reduced, which confirmed this conclusion and indicated that temperature increase could enhance the diffusion of formaldehyde in cellulose. The mechanical parameters of cellulose were analyzed in terms of Young’s modulus, shear modulus, bulk modulus, Poisson’s ratio, and the ratio of bulk modulus to shear modulus (K/G), which were affected by the temperature. The elastic modulus (E, G, and K) of cellulose decreased as the temperature increased, while the Poisson’s ratio V and K/G values increased. The results of the research explain how elevated temperature can promote the release of formaldehyde in furniture from a microscopic perspective, which supports each other with the results of previous experimental data and practical applications in production.

First-Principles Calculations of Elastic Properties of HoBi and ErBi

2013 ◽  
Vol 664 ◽  
pp. 672-676
Author(s):  
De Ming Han ◽  
Gang Zhang ◽  
Li Hui Zhao
Keyword(s):  
Shear Modulus ◽  
Physical Properties ◽  
Bulk Modulus ◽  
Elastic Properties ◽  
Lattice Constant ◽  
Elastic Constants ◽  
First Principles ◽  
Energy Band ◽  
First Principles Calculations ◽  
Future Work

We present first-principles investigations on the elastic properties of XBi (X=Ho, Er) compounds. Basic physical properties, such as lattice constant, elastic constants (Cij), isotropic shear modulus (G), bulk modulus (B), Young’s modulus (Y), Poisson’s ratio (υ), and Anisotropy factor (A) are calculated. The calculated energy band structures show that the two compounds possess semi-metallic character. We hope that these results would be useful for future work on two compounds.

Effect of Swelling Behavior on Elastomeric Materials: Experimental and Numerical Investigation

2013 ◽  
Author(s):  
Sayyad Zahid Qamar ◽  
Maaz Akhtar ◽  
Moosa S. M. Al-Kharusi
Keyword(s):  
Shear Modulus ◽  
Bulk Modulus ◽  
Poisson’S Ratio ◽  
Saline Water ◽  
Numerical Models ◽  
Oil And Gas Industry ◽  
Material Behavior ◽  
Poisson's Ratio ◽  
Energy Potential ◽  
Finite Element Software

In the last ten years, a new type of advanced polymer known as swelling elastomer has been extensively used as sealing element in the oil and gas industry. These elastomers have been instrumental in various new applications such as water shutoff, zonal isolation, sidetracking, etc. Though swell packers can significantly reduce costs and increase productivity, their failure can lead to serious losses. Integrity and reliability of swelling-elastomer seals under different field conditions is therefore a major concern. Investigation of changes in material behavior over a specified swelling period is a necessary first step for performance evaluation of elastomer seals. Current study is based on experimental and numerical analysis of changes in compressive and bulk behavior of an elastomeric material due to swelling. Tests and simulations were carried out before and after various stages of swelling. Specimens were placed in saline water (0.6% and 12% concentration) at a temperature of 50°C, total swelling period being one month. Both compression and bulk tests were conducted using disc samples. A small test rig had to be designed and constructed for determination of bulk modulus. Young’s modulus (under compression) and bulk modulus were determined for specimens subjected to different swelling periods. Shear modulus and Poisson’s ratio were calculated using isotropic relations. Experiments were also simulated using the commercial finite element software ABAQUS. Different hyperelastic material models were examined. As Ogden model with second strain energy potential gave the closest results, it has been used for all simulations. The elastomer was a fast-swell type. There were drastic changes in material properties within one day of swelling, under both low and high salinity water. Values of elastic and shear modulus dropped by more than 90% in the first few days, and then remained almost constant during the rest of the one-month period. Poisson’s ratio, as expected, showed a mirror behavior of a sharp increase in the first few days. Bulk modulus exhibited a fluctuating pattern; rapid initial decrease, then a slightly slower increase, followed by a much slower decrease. Salinity shows some notable effect in the first 5 or 6 days, but has almost no influence in the later days. Very interestingly, Poisson’s ratio approaches the limiting value of 0.5 within the first 10 days of swelling, justifying the assumption of incompressibility used in most analytical and numerical models. In general, simulations results are in good agreement with experimental ones.

scholarly journals Determination of Scale Effects on Mechanical Properties of Berea Sandstone

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Hui Li ◽  
Kaoping Song ◽  
Mingguang Tang ◽  
Ming Qin ◽  
Zhenping Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
Poisson’S Ratio ◽  
Failure Modes ◽  
Shear Failure ◽  
Scale Effects ◽  
Poisson's Ratio ◽  
Axial Splitting ◽  
Rock Mechanical Properties

The key rock mechanical parameters are strength, elastic modulus, Poisson’s ratio, etc., which are important in reservoir development. The accurate determination of reservoir’s mechanical properties is critical to reduce drilling risk and maximize well productivity. Precisely estimating rock mechanical properties is important in drilling and well completion design, as well as crucial for hydraulic fracturing. Rocks are heterogeneous and anisotropic materials. The mechanical properties vary not only with rock types but also with measurement methods, sample geometric dimensions (sample length to diameter ratio and size), and other factors. To investigate sample scale effects on rock mechanical behaviors, unconfined compression tests were conducted on 41 different geometric dimensions of Berea sandstones; unconfined compressive strength (UCS), Young’s modulus ( E ), Poisson’s ratio ( υ ), bulk modulus ( K ), and shear modulus ( G ) were obtained and compared. The results indicate that sample geometry can significantly affect rock mechanical properties: (1) UCS decreases with the increase of length to diameter ratio (LDR), and the UCS standardize factor is between 0.71 and 1.17, which means -30% to +20% variation of UCS with LDR changing from 1 to 6.7. The test results show UCS exhibits positive relationship with sample size. (2) Young’s modulus slightly increases with LDR increases, while Poisson’s ratio decreases with the increase of LDR. For the tested Berea sandstones, Poisson’s ratio standardizing factor is between 0.57 and 1.11. (3) Bulk modulus of Berea sandstone samples decreases with the increase of LDR, while shear modulus increases with LDR increases. Both bulk modulus and shear modulus increase with the increase of sample size. (4) The principal failure modes were analyzed. The failure modes of the tested Berea sandstones are axial splitting and shear failure. Stocky samples ( LDR < 2 ) tend to go axial splitting, while slender samples ( LDR > 2 ) tend to show shear failure.

scholarly journals Elastic Mechanical Properties of 45S5-Based Bioactive Glass–Ceramic Scaffolds

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3244 ◽  
Author(s):  
Francesco Baino ◽  
Elisa Fiume
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Shear Modulus ◽  
Glass Ceramic ◽  
Poisson’S Ratio ◽  
Mechanical Performance ◽  
Poisson's Ratio ◽  
Shear Moduli ◽  
Bioactive Scaffolds

Porosity is recognized to play a key role in dictating the functional properties of bioactive scaffolds, especially the mechanical performance of the material. The mechanical suitability of brittle ceramic and glass scaffolds for bone tissue engineering applications is usually evaluated on the basis of the compressive strength alone, which is relatively easy to assess. This work aims to investigate the porosity dependence of the elastic properties of silicate scaffolds based on the 45S5 composition. Highly porous glass–ceramic foams were fabricated by the sponge replica method and their elastic modulus, shear modulus, and Poisson’s ratio were experimentally determined by the impulse excitation technique; furthermore, the failure strength was quantified by compressive tests. As the total fractional porosity increased from 0.52 to 0.86, the elastic and shear moduli decreased from 16.5 to 1.2 GPa and from 6.5 to 0.43 GPa, respectively; the compressive strength was also found to decrease from 3.4 to 0.58 MPa, whereas the Poisson’s ratio increased from 0.2692 to 0.3953. The porosity dependences of elastic modulus, shear modulus and compressive strength obeys power-law models, whereas the relationship between Poisson’s ratio and porosity can be described by a linear approximation. These relations can be useful to optimize the design and fabrication of porous biomaterials as well as to predict the mechanical properties of the scaffolds.

Elastic Constants of Magnesium Thorium Alloy

1967 ◽  
Vol 89 (1) ◽  
pp. 93-97
Author(s):  
J. R. Asay
Keyword(s):  
Shear Modulus ◽  
Bulk Modulus ◽  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Young's Modulus ◽  
Longitudinal Velocity ◽  
Shear Velocity ◽  
Polycrystalline Sample ◽  
Poisson's Ratio ◽  
Wave Measurements

The longitudinal and shear wave velocities in a polycrystalline sample of magnesium thorium alloy were measured by a pulse transmission technique as a function of temperature. Temperatures ranged from 25 C to about 350 deg C for longitudinal wave measurements and to about 220 deg C for shear measurements. The resulting velocity data were used to calculate various elastic properties of the material, including Young’s modulus, shear modulus, bulk modulus, and Poisson’s ratio. The resulting least squares fits for these data are: Longitudinal velocity, cl = 5.749 − 3.987 × 10−4T − 1.139 × 10−6T2mm/μsec; shear velocity, ct = 3.108 − 1.421 × 10−4T − 2.588 × 10−6T2mm/μsec; bulk modulus, B = 3.576 × 10″ − 2.744 × 107T + 1.187 × 105T2 dynes/cm2; Young’s modulus, E = 4.435 × 10″ − 1.415 × 107T = 6.037 × 105T2 dynes/cm2; shear modulus, G = 1.716 × 10″ − 7.994 × 106T − 2.619 × 105T2 dynes/cm2; Poisson’s ratio, σ = 0.293 − 6.459 × 10−6T + 3.392 × 10−7T2.

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