Pressure induced stiffening, thermal softening of bulk modulus and brittle nature of mercury chalcogenides

2015 ◽  
Vol 04 (03) ◽  
pp. 1550015
Author(s):  
Dinesh Varshney ◽  
Swarna Shriya ◽  
Raju Sapkale ◽  
Meenu Varshney ◽  
M. Ameri
Keyword(s):  
Bulk Modulus ◽  
Poisson’S Ratio ◽  
Anisotropy Parameter ◽  
Zero Point ◽  
Elastic Wave Velocity ◽  
Poisson's Ratio ◽  
Interionic Interaction ◽  
Point Energy ◽  
Mercury Chalcogenides ◽  
Range Overlap

The pressure and temperature dependent elastic properties of mercury chalcogenides ( Hg X; X = S , Se and Te ) with pressure induced structural transition from ZnS -type (B3) to NaCl -type (B1) structure have been analyzed within the framework of a model interionic interaction potential with long-range Coulomb and charge transfer interactions, short-range overlap repulsion and van der Waals (vdW) interactions as well as zero point energy effects. Emphasis is on the evaluation of the Bulk modulus with pressure and temperature dependency to yield the Poisson's ratio ν, the Pugh ratio ϕ, anisotropy parameter, Shear and Young's modulus, Lamé's constant, Klein man parameter, elastic wave velocity and Debye temperature. The Poisson's ratio behavior infers that Hg X are brittle in nature. To our knowledge this is the first quantitative theoretical prediction of the pressure dependence of elastic and thermodynamical properties explicitly the ductile (brittle) nature of Hg X and still awaits experimental confirmations.

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.

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.

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 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.

First–Principles Study Including Zero Point Energy on Hydrogen in Palladium for Hydrogen Membranes Applications

2014 ◽  
Vol 875-877 ◽  
pp. 635-641
Author(s):  
Ali Marashdeh
Keyword(s):  
Bulk Modulus ◽  
Density Functional ◽  
Direct Method ◽  
Harmonic Approximation ◽  
Zero Point ◽  
Density Functional Theory Calculations ◽  
Generalized Gradient ◽  
Zero Point Energy ◽  
Point Energy ◽  
Metal Lattice

Density functional theory calculations at the generalized gradient approximation level are performed on cube clusters that comprise both the metal lattice (Pd) and the interstitial lattice (H). The calculations consider H on the octahedral sites of the metal lattice, i.e., cubes structures Pd4H4-x(x=0–4). For each structure, the cell volume, the total energy, the bulk modulus and the derivative of the bulk modulus have been calculated. Zero point energy (ZPE) corrections have been included using the direct method. The calculations confirm that including ZPE effects in the harmonic approximation has a significant effect on the calculated properties by increasing the cell-volumes and decreasing the bulk modulus. The absorption energies of hydrogen in palladium without including ZPE are found to be exothermic processes. When the ZPE is included, adding the first three Hs atom are exothermic processes while the fourth atom is found to be endothermic.

scholarly journals Thermally Tunable Dynamic and Static Elastic Properties of Hydrogel Due to Volumetric Phase Transition

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1462 ◽  
Author(s):  
Yuqi Jin ◽  
Teng Yang ◽  
Shuai Ju ◽  
Haifeng Zhang ◽  
Tae-Youl Choi ◽  
...  
Keyword(s):  
Phase Transition ◽  
Bulk Modulus ◽  
Young’S Modulus ◽  
Elastic Properties ◽  
Poisson’S Ratio ◽  
Young's Modulus ◽  
Poisson's Ratio ◽  
Solution Temperature ◽  
Temperature Sensitive ◽  
Alginate Hydrogel

The temperature dependence of the mechanical properties of polyvinyl alcohol-based poly n-isopropyl acrylamide (PVA-PNIPAm) hydrogel was studied from the static and dynamic bulk modulus of the material. The effect of the temperature-induced volumetric phase transition on Young’s Modulus, Poisson’s ratio, and the density of PVA-PNIPAm was experimentally measured and compared with a non-thermo-responsive Alginate hydrogel as a reference. An increase in the temperature from 27.5 to 32 °C results in the conventional temperature-dependent de-swelling of the PVA-PNIPAm hydrogel volume of up to 70% at the lower critical solution temperature (LCST). However, with the increase in temperature, the PVA-PNIPAm hydrogel showed a drastic increase in Young’s Modulus and density of PVA-PNIPAm and a corresponding decrease in the Poisson’s ratio and the static bulk modulus around the LCST temperature. The dynamic bulk modulus of the PVA-PNIPAm hydrogel is highly frequency-dependent before the LCST and highly temperature-sensitive after the LCST. The dynamic elastic properties of the thermo-responsive PVA-PNIPAm hydrogel were compared and observed to be significantly different from the thermally insensitive Alginate hydrogel.

Sign in / Sign up

Export Citation Format

Share Document