Mechanical and thermodynamics properties of Al2Ca and Mg2Ca under various pressure: A first principle study

2021 ◽  
Vol 11 (9) ◽  
pp. 1571-1578
Author(s):  
Zai Gao Huang
Keyword(s):  
Shear Modulus ◽  
Bulk Modulus ◽  
Young’S Modulus ◽  
Elastic Constants ◽  
Coefficient Of Thermal Expansion ◽  
Young's Modulus ◽  
Structural Parameters ◽  
Harmonic Approximation ◽  
Polycrystalline Materials ◽  
Ductile Phase

The mechanical and thermodynamic properties of Al2Ca and Mg2Ca in the pressure range of 0~100 Gpa were investigated using first-principles calculations. The structural parameters, such as lattice constant ratio, unit cell volume ratio, density, were investigated. The calculated elastic constants satisfy the born’s stability criterion, indicating that they are mechanically stable at normal and high pressure. Mechanical parameters such as bulk modulus, shear modulus, and Young’s modulus of polycrystalline materials have been derived from single-crystal elastic constants. The Poisson’s ratio and anisotropy were investigated. The results show that the B/G value of Mg2Ca is greater than 1.75, indicating it is a ductile phase under various pressures. When the pressure was equal to 40 Gpa, Al2Ca was transferred brittle to toughness, and the bulk modulus, shear modulus, and Young’s modulus of Al2Ca were all larger than those of Mg2Ca, indicating that the comprehensive mechanical properties of Al2Ca are better than those of Mg2Ca. The constant heat capacity obtained by the quasi-harmonic approximation indicates that the ability of Mg2Ca to release or store heat is greater than that of Al2Ca. Moreover, the coefficient of thermal expansion (α) increases exponentially at lower temperatures and linearly at higher temperatures for both alloys.

Lattice dynamical and elastic properties of BaFX (X = Cl, Br and I): Matlockite structure compounds

2019 ◽  
Vol 33 (20) ◽  
pp. 1950221 ◽  
Author(s):  
A. K. Kushwaha ◽  
S. Akbudak ◽  
A. C. Yadav ◽  
Ş. Uğur ◽  
G. Uğur
Keyword(s):  
Shear Modulus ◽  
Bulk Modulus ◽  
Young’S Modulus ◽  
Elastic Constants ◽  
Phonon Mode ◽  
Young's Modulus ◽  
Nearest Neighbors ◽  
Crystallographic Direction ◽  
Theoretical Results ◽  
Rigid Ion Model

In this study, an eleven-parameter rigid-ion model (RIM) is proposed for BaFX (X = Cl, Br and I) matlockite structure compounds. The interatomic interactions up to fourth nearest neighbors for the studied compounds are calculated. The zone-center raman and infrared phonon mode frequencies, elastic constants, bulk modulus B, shear modulus G, Young’s modulus E, Poisson’s coefficient, Debye temperature and sound velocity along [100], [110] and [001] directions have been calculated. It is observed that the studied BaFCl, BaFBr and BaFI compounds are stiffer in [100] direction than [001] crystallographic direction and the bulk modulus, shear modulus and Young’s modulus of the studied compounds decrease in the order of BaFCl [Formula: see text] BaFBr [Formula: see text] BaFI. The obtained results are compared with the theoretical and experimental results. It is observed that the obtained results agree very well with the experimental and theoretical results available in the literature.

Elastic constants of inflated lobes of dog lungs

1976 ◽  
Vol 40 (4) ◽  
pp. 508-513 ◽  
Author(s):  
S. J. Lai-Fook ◽  
T. A. Wilson ◽  
R. E. Hyatt ◽  
J. R. Rodarte
Keyword(s):  
Bulk Modulus ◽  
Young’S Modulus ◽  
Elastic Constants ◽  
Young's Modulus ◽  
Poisson Ratio ◽  
Inflation Pressure ◽  
Initial State ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Indentation Tests

The elastic constants of dog lungs were determined at various degrees of inflation. In one set of experiments, the lobes were subjected to deformations that approximated the conditions of uniaxial loading. These data, together with the bulk modulus data obtained from the local slope of the pressure-volume curve, were used to determine the two elastic moduli that are needed to describe small nonuniform deformations about an initial state of uniform inflation. The bulk modulus was approximately 4 times the inflation pressure, and Young's modulus was approximately 1.5 times the inflation pressure. In a second set of experiments, lobes were subjected to indentation tests using cylindric punches 1–3 cm in diameter. The value for Young's modulus obtained from these data was slightly higher, approximately twice the inflation pressure. These experiments indicate that the lung is much more easily deformable in shear than in dilatation and that the Poisson ratio for the lung is high, approximately 0.43.

scholarly journals Studies on Structure and Elasto-Mechanical Properties of Suvin Cotton Fibre

2020 ◽  
Vol 12 (4) ◽  
pp. 607-620
Author(s):  
V. V. Manju ◽  
S. Divakara ◽  
R. Somashekar
Keyword(s):  
Shear Modulus ◽  
Young’S Modulus ◽  
Elastic Constants ◽  
Web Application ◽  
Young's Modulus ◽  
Least Square Method ◽  
Elastic Stiffness ◽  
Cotton Fibre ◽  
Least Square ◽  
3 Dimensional

The comprehensive elastic properties of Suvin cotton fibre have been estimated. The Linked Atom Least Square method (LALS) technique has been employed to compute the structural properties using the X-ray diffraction data. Using Treloar’s assumptions the elastic stiffness matrix |Cij| has been calculated, then by utilizing the Voigt theory the elastic constants like Young’s modulus (E), Bulk modulus (K), Shear modulus (G), Poisson’s ratio (ν) and linear compressibility (β) have been estimated. Further, the experimental results of elastic constants are obtained and compared with the computed results and a broad correlation between them has been observed. ELATE web application tool is used to obtain the 3-dimensional images of variation of elastic constants along their spatial axes. From these figures an attempt has been made to explain the anisotropic mechanical property with respect to directional dependent Young’s modulus (E) and Shear modulus properties (G).

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.

Elastic constants of trapped lung parenchyma

1978 ◽  
Vol 44 (6) ◽  
pp. 853-858 ◽  
Author(s):  
S. J. Lai-Fook ◽  
R. E. Hyatt ◽  
J. R. Rodarte
Keyword(s):  
Shear Modulus ◽  
Young’S Modulus ◽  
Elastic Constants ◽  
Young's Modulus ◽  
Indentation Test ◽  
Lung Parenchyma ◽  
Accurate Estimate ◽  
The Other ◽  
Indentation Tests ◽  
Trapped Lung

Isolated dog lobes were maximally trapped with air, and their parenchymal elastic properties were measured at the trapped volume. Indentation tests were performed on the surface of the lobes, followed by uniaxial and torsion tests on excised pieces of parenchyma. Similar values for Young's modulus were obtained from the indentation and uniaxial tests. The values for the shear modulus from the torison tests also were consistent with Young's modulus measured by the other procedures. The indentation test provided an accurate estimate of Young's modulus or the shear modulus for trapped lobes, and the results suggest that it is a valid method for estimating these constants in nontrapped lobes.

Relaxor Single-Crystal Plates with Nano-Size Ferroelectric Domains Applying to Ultrasonic Prove for Medical Uses

2016 ◽  
Vol 102 ◽  
pp. 57-64
Author(s):  
Toshio Ogawa ◽  
Taiki Ikegaya
Keyword(s):  
Bulk Modulus ◽  
Single Crystal ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Young’S Modulus ◽  
Elastic Constants ◽  
Poisson’S Ratio ◽  
Young's Modulus ◽  
Poisson's Ratio ◽  
Domain Alignment

Sound velocities were measured in relaxor single-crystal plates, included in piezoelectric transducers for medical uses, using an ultrasonic precision thickness gauge with high-frequency pulse generation. The velocities were compared with the ones of piezoelectric ceramics in order to clarify characteristics of the single crystals. Estimating the difference in the sound velocities and elastic constants in the single crystals and ceramics, it was possible to evaluate effects of domain and grain boundaries on elastic constants. Existence of domain boundaries in single crystal affected the decrease in Young’s modulus, rigidity, Poisson’s ratio and bulk modulus. While existence of grain boundaries affected the decrease in Young’s modulus and rigidity, Poisson’s ratio and bulk modulus increased. It was thought these phinomina come from domain alignment by DC poling, and both the boundaries act as to absorb mechanical stress by defects due to the boundaries. In addition, the origin of piezoelectricity in single crystals is caused by low bulk modulus and Poisson’s ratio, and high Young’s modulus and rigidity in comparison with ceramics. On the contrary, the origin of piezoelectricity in ceramics is caused by high Poisson’s ratio by high bulk modulus, and furthermore, low Young’s modulus and rigidity due to domain alignment.

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.

First-Principles Study of Structural, Mechanical, and Thermodynamic Properties of Refractory Metals (Rh, Ir, W, Ta, Nb, Mo, Re, and Os)

2020 ◽  
Vol 993 ◽  
pp. 1017-1030
Author(s):  
Ying Jie Sun ◽  
Kai Xiong ◽  
Zong Bo Li ◽  
Shun Meng Zhang ◽  
Yong Mao
Keyword(s):  
Thermodynamic Properties ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
Young’S Modulus ◽  
First Principles ◽  
Elastic Anisotropy ◽  
Young's Modulus ◽  
Refractory Metals ◽  
Body Centered Cubic ◽  
Cubic Metals

The structural, mechanical, and thermodynamic properties of refractory metals Rh, Ir, W, Ta, Nb, Mo, Re, and Os have been systematically investigated by first-principles calculations based on density functional theory. Comparative studies reveal that Young's modulus (E = 636.42 GPa), shear modulus (G = 256.81 GPa), bulk modulus (B = 406.55 GPa), and microhardness (H = 44.69 GPa) of hexagonal Os are the highest, which reveals Os has the best overall mechanical properties. The body-centered cubic Nb has the smallest Young's modulus (E = 94.76 GPa), shear modulus (G = 33.62 GPa), bulk modulus (B = 174.50 GPa), and hardness (H = 2.04 GPa). Based on the ratio of bulk to shear modulus, it is judged that Rh, Ir, and Os are brittle materials (B/G < 1.75), and Nb, Ta, Mo, W, and Re exhibit ductile (B/G > 1.75). The elastic anisotropy has also been discussed by plotting both the 3D contours and the 2D planar projections of Young's modulus. For the face-centered cubic metals Rh and Ir and hexagonal close-packed metals Re and Os, the 3D contours of the Young's modulus are very similar, whereas body-centered cubic metals Ta, W, Nb, and Mo exhibit significant difference in elastic anisotropy. The thermodynamic calculations show that Debye temperature and minimum thermal conductivity decreases along Rh, Os, Mo, Ir, Re, W, Ta, Nb sequence. Furthermore, the results can be used as a general guidance for the design and development of high temperature refractory alloy system.

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