A study of the inconsistent observations in the fault-plane project

1958 ◽  
Vol 48 (1) ◽  
pp. 17-31
Author(s):  
J. H. Hodgson ◽  
W. M. Adams
Keyword(s):  
Poisson’S Ratio ◽  
Significant Variation ◽  
Fault Plane ◽  
Epicentral Distance ◽  
Density Ratio ◽  
Poisson's Ratio ◽  
Final Conclusion ◽  
The Core

Abstract The 65 solutions published in the fault-plane project of the Dominion Observatory have been based on 2,476 observations of P and 722 observations of PKP. Of these observations 18.3 per cent have been inconsistent with the published solutions, but a small number of stations have contributed a high percentage of these inconsistencies. Applying a criterion of rejection to the data reduces the percentage of inconsistencies to 14 per cent. Considering that most stations have tried to co�ate as fully as possible in the programme and have reported observations even when the arrivals were recorded only as weakly emergent phases, this percentage seems satisfactorily small. Because the circles represent the boundaries between zones of compression and zones of dilatation, it might be expected that a higher percentage of inconsistencies would occur close to the circles. The reverse has been found; the observations close to the circular boundaries are slightly more accurate than those remote from them. The inconsistent observations show no significant variation with epicentral distance except that the percentage of inconsistencies is high at the shorter distances. This is the effect of the crustal layers, and had been anticipated. There have been 282 observations of PP and 135 observations of pP. These observations were examined to determine whether they could be used to determine the value of Poisson's ratio under the continents and under the oceans. It was found that the percentage of inconsistencies was too high to allow a final conclusion. There were 17 observations of PcP. These were examined following a method suggested by B䳨 in an attempt to define the density ratio at the boundary of the core. The attempt was a failure because of the inconsistency of the data. The failure of the reflected phases suggested that the data from them might be random. To test this, 23 new solutions were carried out based only on P and PKP data. When the solutions were complete, observations for the reflected phases were plotted on the diagrams. It was found that for all reflected phases the inconsistencies approached 50 per cent. It is clear that reflected phases, at least when reported by questionnaires, are not sufficiently accurate to be useful in fault-plane studies.

Polypropylene structural foams: Measurements of the core, skin, and overall mechanical properties with evaluation of predictive models

2016 ◽  
Vol 53 (1) ◽  
pp. 25-44 ◽  
Author(s):  
Tarik Sadik ◽  
Caroline Pillon ◽  
Christian Carrot ◽  
José A Reglero Ruiz ◽  
Michel Vincent ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Poisson’S Ratio ◽  
Flexural Modulus ◽  
Tensile Modulus ◽  
Poisson's Ratio ◽  
Injection Molding Process ◽  
Mixing Rule ◽  
Molding Process ◽  
Plane Shear ◽  
The Core

Relationships for the prediction of various linear mechanical properties of polymeric sandwich foams obtained in injection processes were studied in comparison with shear, tensile, and flexural tests. The samples were obtained by a core-back foam injection molding process that enables one to obtain sandwich materials with dense skins and a foamed core as revealed by the morphological analysis. Tensile, shear, and flexural moduli were investigated for the skin, the core, and the overall foamed structure. In addition, the Poisson’s ratio of the skin was also determined. The core properties were specifically analyzed by machining the samples and removing the skins. Tensile and shear properties of the core can be well described by the Moore equation. The tensile modulus can be calculated by a linear mixing rule with the moduli of the skin and of the core in relation to the thickness of the layers. Shear and flexural moduli are described by a linear mixing rule on the rigidity in agreement with the mechanics of beams. Tensile modulus, out-of-plane shear modulus, and flexural modulus can finally be predicted by the knowledge of only very few data, namely the tensile modulus and Poisson’s ratio of the matrix, the void fraction, and thickness of the core. The equations were proved to be physically meaningful and consistent with each other.

scholarly journals Effects of Pressurizing Cryogenic Treatments on Physical and Mechanical Properties of Shale Core Samples—An Experimental Study

Gases ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 33-50
Author(s):  
Rayan Khalil ◽  
Hossein Emadi ◽  
Faisal Altawati
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Young's Modulus ◽  
Cryogenic Treatment ◽  
Poisson's Ratio ◽  
The Core ◽  
Core Samples ◽  
Bulk Compressibility ◽  
Core Holder

The technique of cryogenic treatments requires injecting extremely cold fluids such as liquid nitrogen (LN2) into formations to create fractures in addition to connecting pre-existing fracture networks. This study investigated the effects of implementing and pressurizing cryogenic treatment on the physical (porosity and permeability) and mechanical properties (Young’s modulus, Poisson’s ratio, and bulk compressibility) of the Marcellus shale samples. Ten Marcellus core samples were inserted in a core holder and heated to 66 °C using an oven. Then, LN2 (−177 °C) was injected into the samples at approximately 0.14 MPa. Nitrogen was used to pressurize nine samples at injection pressures of 1.38, 2.76, and 4.14 MPa while the tenth core sample was not pressurized. Using a cryogenic pressure transducer and a T-type thermocouple, the pressure and temperature of the core holder were monitored and recorded during the test. The core samples were scanned using a computed tomography (CT) scanner, and their porosities, permeability, and ultrasonic velocities were measured both before and after conducting the cryogenic treatments. The analyses of CT scan results illustrated that conducting cryogenic treatments created new cracks inside all the samples. These cracks increased the pore volume, and as a result, the porosity, permeability, and bulk compressibility of the core samples increased. The creations of the new cracks also resulted in reductions in the compressional and shear velocities of the samples, and as a result, decreasing the Young’s modulus and Poisson’s ratio. Moreover, the results revealed that pressurizing the injected LN2 increased the alterations of aforementioned properties.

Development of helical auxetic yarn with negative Poisson’s ratio by combinations of different materials and wrapping angle

2020 ◽  
pp. 152808372094111
Author(s):  
Tehseen Ullah ◽  
Sheraz Ahmad ◽  
Yasir Nawab
Keyword(s):  
Poisson’S Ratio ◽  
Transverse Direction ◽  
Poisson Ratio ◽  
Longitudinal Direction ◽  
Poisson's Ratio ◽  
Negative Poisson’S Ratio ◽  
The Core ◽  
Inverse Effect ◽  
Wrap Angle ◽  
Negative Poisson's Ratio

Auxetic materials have negative Poisson ratio which has a multiple ranges of functional applications. The helical auxetic yarn was successfully developed through direct twist system by using core and wrap yarn or filament, which shows Auxeticity when the HAY is stretched in longitudinal direction in response it expand in transverse direction, Helical Auxetic Yarns were developed using various parameters of the core and warp filament, these parameters are wrapping angle (Twist per meter), diameter ratio, and modulus ratio. The strength of Helical yarn was characterized using single yarn strength and Image J software was used for the calculation of poisson’s ratio. According to test results, it is concluded that the core filament of helical auxetic yarn increased its thickness in transverse direction under stress, and a considerable negative poisson’s ratio was calculated. The values of negative poisson’s ratio described that the auxeticity had a direct relation with core filament thickness or diameter and inversely proportional to the linear density of wrap filament, in case of the wrap angle the auxeticity of HAY yarn had an inverse effect with wrap angle. Kevlar/polypropylene combination sample showed maximum auxeticity at a 15-degree angle while Kevlar/nylon combination sample showed minimum auxeticity at a 25-degree wrap angle.

scholarly journals Oligomodal metamaterials with multifunctional mechanics

2021 ◽  
Vol 118 (21) ◽  
pp. e2018610118
Author(s):  
Aleksi Bossart ◽  
David M. J. Dykstra ◽  
Jop van der Laan ◽  
Corentin Coulais
Keyword(s):  
Poisson’S Ratio ◽  
Shape Change ◽  
Density Ratio ◽  
Deformation Mode ◽  
System Size ◽  
Combinatorial Design ◽  
Poisson's Ratio ◽  
Zero Energy ◽  
Wide Range ◽  
Deformation Modes

Mechanical metamaterials are artificial composites that exhibit a wide range of advanced functionalities such as negative Poisson’s ratio, shape shifting, topological protection, multistability, extreme strength-to-density ratio, and enhanced energy dissipation. In particular, flexible metamaterials often harness zero-energy deformation modes. To date, such flexible metamaterials have a single property, for example, a single shape change, or are pluripotent, that is, they can have many different responses, but typically require complex actuation protocols. Here, we introduce a class of oligomodal metamaterials that encode a few distinct properties that can be selectively controlled under uniaxial compression. To demonstrate this concept, we introduce a combinatorial design space containing various families of metamaterials. These families include monomodal (i.e., with a single zero-energy deformation mode); oligomodal (i.e., with a constant number of zero-energy deformation modes); and plurimodal (i.e., with many zero-energy deformation modes), whose number increases with system size. We then confirm the multifunctional nature of oligomodal metamaterials using both boundary textures and viscoelasticity. In particular, we realize a metamaterial that has a negative (positive) Poisson’s ratio for low (high) compression rate over a finite range of strains. The ability of our oligomodal metamaterials to host multiple mechanical responses within a single structure paves the way toward multifunctional materials and devices.

Dynamic Stresses and Displacements Around Cylindrical Discontinuities Due to Plane Harmonic Shear Waves

1963 ◽  
Vol 30 (4) ◽  
pp. 598-604 ◽  
Author(s):  
C. C. Mow ◽  
L. J. Mente
Keyword(s):  
Rigid Body ◽  
Incident Wave ◽  
Rigid Inclusion ◽  
Poisson’S Ratio ◽  
Density Ratio ◽  
Body Motion ◽  
Poisson's Ratio ◽  
Wave Number ◽  
Plane Shear ◽  
Dynamic Stresses

The problem of dynamic stresses and displacements around a cavity and rigid inclusion of arbitrary density is examined for an elastic medium during the passage of a plane shear wave. In the cavity case, the dynamic stresses and displacements are found to be dependent upon the incident wave number and Poisson’s ratio of the medium. In the rigid-inclusion case it is found that dynamic stresses and the rigid-body rotation and translation are dependent upon the incident wave numbers, the Poisson’s ratio, and the density ratio of the medium and the insert. Close coupling is observed between the stresses and the rigid-body motion of the insert.

On the determination of the polarization angle of the S wave

1962 ◽  
Vol 52 (1) ◽  
pp. 95-107
Author(s):  
Otto Nuttli ◽  
John D. Whitmore
Keyword(s):  
Wave Velocity ◽  
Particle Motion ◽  
Poisson’S Ratio ◽  
Epicentral Distance ◽  
Critical Distance ◽  
P Wave ◽  
Poisson's Ratio ◽  
Polarization Angle ◽  
Angle Of Incidence ◽  
S Wave

Abstract This study is concerned with determining the minimum epicentral distance for which it is permissible to obtain the value of the polarization angle of the S wave by measuring the angle between the great circle path at the station and the direction of the horizontal component of the S wave particle motion obtained from the seismograms. This critical distance can be determined by the fact that at smaller distances the particle motion of the earth's surface due to the incidence of S will be nonlinear (the SH and the horizontal and vertical components of SV will be out of phase with respect to one another) while at larger distances the particle motion will be linear. An analysis of the S motion recorded by the Galitzin-Wilip seismographs at Florissant indicates that the critical distance is 42 degrees. The periods of these S waves are of the order of 10 second. The analysis also shows that the effective P wave velocity of teleseismic waves at the earth's free surface is 7.74 km/sec, and the effective value of Poisson's ratio and the effective S wave velocity at the earth's surface are 0.25 and 4.46 km/sec, respectively. By effective values are meant the values of the velocities and Poisson's ratio that govern the angle of incidence of the waves at the earth's surface.

Intensification of auxetic effect in high stiffness auxetic yarns with potential application as the reinforcing element of composite

2020 ◽  
pp. 152808372097891
Author(s):  
Asal Lolaki ◽  
Mohammed Zarrebini ◽  
Davood Mostofinejad ◽  
Mohsen Shanbeh ◽  
Sayyed Mahdi Abtahi
Keyword(s):  
Composite Materials ◽  
Poisson’S Ratio ◽  
Steel Wire ◽  
Poisson's Ratio ◽  
The Core ◽  
High Stiffness ◽  
Composite Yarn ◽  
Dependent Behavior ◽  
Core Components ◽  
Strain Dependent

Helical auxetic yarn (HAY) is a newly developed composite yarn with negative Poisson’s ratio. HAYs offers advantageous merits as a reinforcing element in composite materials. In this paper high stiffness HAYs composed of Nylon filament core and fine steel wire wrap yarns were developed. The importance of the stiffness ratio of the wrap to the core components in the resultant auxetic yarn was examined. The differences between instantaneous and engineering Poisson’s ratio analyses in the understanding of the strain-dependent behavior of HAY was investigated. Results revealed that the utilization of the fine steel multifilament in the developed HAY samples enormously improves the stiffness of HAY. It was possible to obtain an elastic modulus of 9 GPa and a maximum auxetic effect of –16.82 in the samples. It was concluded that such highly stiff auxetic yarn can successfully be used as reinforcement in various composite materials such as cementitious composites.

Spatial delineation of rock types in the Meramec formation by integrating core and seismic measurements, Loyal Area, Kingfisher Co, Anadarko Basin

2021 ◽  
pp. 1-31
Author(s):  
Swetal Patel ◽  
Ishank Gupta ◽  
Jing Fu ◽  
Ali Tinni ◽  
Kurt. J. Marfurt ◽  
...  
Keyword(s):  
Elastic Property ◽  
Poisson’S Ratio ◽  
Rock Type ◽  
Fracture Network ◽  
Poisson's Ratio ◽  
S Wave ◽  
The Core ◽  
Rock Types ◽  
Seismic Resolution ◽  
Porosity And Permeability

The Mississippian-age STACK area of Oklahoma is one of the more important new resource plays in North America. It consists of mudrock, siltstone, and carbonate reservoirs, some of which are self-sourced and all of which require hydraulic fracturing to be economical. The efficacy of the fracturing relies on whether the created fracture network drains from producible rock types. We integrated data at both core and seismic resolution to map the lateral and vertical variation of the rock types for this new play. We measured porosity, permeability, saturated P- and S- wave velocity and density in the lab at 2 ft. intervals on the cores. We then defined rock types based on porosity and permeability measurements. We mapped these rock types against alternative elastic property cross plots, including P-impedance, S-impedance, Poisson’s ratio, LamdaRho, and MuRho. P- and S- impedance are the only two independent elastic properties measured on the core samples. Hence, the rock types showed equal sensitivity to all the elastic property pairs. We observe a 30% difference between core and seismic elastic values, only part of which can be attributed to dispersion and the discrepancy is addressed simple linear scaling. We found that P-impedance and Poisson’s ratio core measurements were easier to scale linearly to the corresponding seismic frequency measurements. Once scaled, we used Bayesian classification to map the P-impedance and Poisson’s ratio rock type template defined by the core measurements to the same elastic parameters estimated by inversion. As we move away from the cored wells, we encounter P-impedance/Poisson’s ratio pairs not seen in core, resulting in areas where the rock type is “unknown”. The seismically predicted rock types show an excellent correlation at the well locations and provided stratigraphically reasonable images away from the wells, suggesting that more cored wells can classify these unknown rock types.

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