SECONDARY ARRIVALS IN A WELL VELOCITY SURVEY

Geophysics ◽  
1943 ◽  
Vol 8 (3) ◽  
pp. 290-296
Author(s):  
C. W. Horton
Keyword(s):  
Bulk Modulus ◽  
Poisson’S Ratio ◽  
Poisson's Ratio ◽  
Secondary Wave ◽  
Transverse Waves ◽  
A Value

Seismograms obtained in a well survey of the Shell‐Longleaf Lumber Co. #1, Vernon Parish, Louisiana, showed well‐developed secondary arrivals which satisfied a velocity formula V = (2000+0.27Z) feet per second. If these arrivals are assumed to be transverse waves, a value of 0.43 for Poisson’s ratio is obtained. On this same assumption, values of the modulus of rigidity and bulk modulus are computed for various depths. It is shown that the velocity of the secondary wave does not satisfy the equation developed by Lamb for thick‐walled tube waves.

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.

scholarly journals An Anisotropic Auxetic 2D Metamaterial Based on Sliding Microstructural Mechanism

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 429 ◽  
Author(s):  
Teik-Cheng Lim
Keyword(s):  
Poisson’S Ratio ◽  
Nearest Neighbor ◽  
Rapid Change ◽  
Poisson's Ratio ◽  
Rectangular Array ◽  
A Value ◽  
Angular Change ◽  
Unit Cells ◽  
Square Array ◽  
Axes Of Symmetry

A new 2D microstructure is proposed herein in the form of rigid unit cells, each taking the form of a cross with two opposing crossbars forming slots and the other two opposing crossbars forming sliders. The unit cells in the microstructure are arranged in a rectangular array in which the nearest four neighboring cells are rotated by 90° such that a slider in each unit cell is connected to a slot from its nearest neighbor. Using a kinematics approach, the Poisson’s ratio along the axes of symmetry can be obtained, while the off-axis Poisson’s ratio is obtained using Mohr’s circle. In the special case of a square array, the results show that the Poisson’s ratio varies between 0 (for loading parallel to the axes) and −1 (for loading at 45° from the axes). For a rectangular array, the Poisson’s ratio varies from 0 (for loading along the axes) to a value more negative than −1. The obtained results suggest the proposed microstructure is useful for designing materials that permit rapid change in Poisson’s ratio for angular change.

The azimuthal and polar radiation patterns obtained from a horizontal stress applied at the surface of an elastic half space

1962 ◽  
Vol 52 (1) ◽  
pp. 27-36
Author(s):  
J. T. Cherry
Keyword(s):  
Surface Wave ◽  
Half Space ◽  
Rayleigh Waves ◽  
Poisson’S Ratio ◽  
Horizontal Stress ◽  
Elastic Half Space ◽  
The Body ◽  
Body Waves ◽  
Poisson's Ratio ◽  
A Value

Abstract The body waves and surface waves radiating from a horizontal stress applied at the free surface of an elastic half space are obtained. The SV wave suffers a phase shift of π at 45 degrees from the vertical. Also, a surface wave that is SH in character but travels with the Rayleigh velocity is shown to exist. This surface wave attenuates as r−3/2. For a value of Poisson's ratio of 0.25 or 0.33, the amplitude of the Rayleigh waves from a horizontal source should be smaller than the amplitude of the Rayleigh waves from a vertical source. The ratio of vertical to horizontal amplitude for the Rayleigh waves from the horizontal source is the same as the corresponding ratio for the vertical source for all values of Poisson's ratio.

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.

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