Journal articles: 'Complex Poisson's ratio'

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Pritz, T. "Measurement methods of complex Poisson's ratio of viscoelastic materials." Applied Acoustics 60, no. 3 (July 2000): 279–92. http://dx.doi.org/10.1016/s0003-682x(99)00049-3.

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Rouleau, Lucie, Isadora Ruas Henriques, and Jean-François Deü. "Influence of the Poisson's ratio on the efficiency of viscoelastic damping treatments." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 3 (August 1, 2021): 3790–94. http://dx.doi.org/10.3397/in-2021-2521.

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An efficient way of mitigating noise and vibration is to embed viscoelastic patches into the host structure. Viscoelastic properties are of significant importance in determining the performance of the passive damping treatment. The behaviour of homogeneous isotropic materials is described by two elastic constants (generally the Young modulus and the Poisson ratio, or the shear and bulk moduli), which are frequency- and temperature-dependent in the case of viscoelastic materials. In practice, the Poisson's ratio is often considered as independent of temperature and frequency. One goal of this work is to numerically evaluate the validity of this assumption and its limitations (frequency range, thickness of the viscoelastic layer). To this end, a thermo-mechanical characterization of a viscoelastic material is carried out by dynamic measurements of the complex shear and bulk moduli, allowing the indirect measurement of the frequency- and temperature-dependent Poisson's ratio. Moreover, the measurements of the Poisson's ratio (direct or indirect) can lead to considerable uncertainties. For instance, large discrepancies have been observed when characterizing the Poisson's ratio of polymer foams. Another goal of this work is to investigate the influence of those uncertainties on the dynamic response of a damped structure.

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Šimić Penava, Diana, Željko Penava, and Marijana Tkalec. "Influence of Coating on the Poisson's Ratio of Woven Fabrics." Applied Mechanics and Materials 827 (February 2016): 27–30. http://dx.doi.org/10.4028/www.scientific.net/amm.827.27.

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Coated fabrics have complex composite structure whose mechanical properties are considerably improved in relation with the initial basic material. They are obtained by applying a certain number of coatings to raw fabrics. In this paper the practical application of uniaxial testing of coated fabrics for determining its breaking properties and Poisson’s ratio is presented. Due to the anisotropy of woven and coated fabrics, Poisson's ratio changes over the fabric sample stretching. Experimental testing were carried out on two samples of plain weave cotton fabrics. The fabrics were tested before coating, and after one, two and three coatings. Samples are stretched with tensile force in the weft and warp direction, and based on different measured values of fabric stretching, warp and weft Poisson's ratio is calculated. The values of tensile force and relative extension of coated fabrics were measured, and breaking force values, elongation at break, contractions at break.

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Pritz, T. "FREQUENCY DEPENDENCES OF COMPLEX MODULI AND COMPLEX POISSON'S RATIO OF REAL SOLID MATERIALS." Journal of Sound and Vibration 214, no. 1 (July 1998): 83–104. http://dx.doi.org/10.1006/jsvi.1998.1534.

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Holownia, B. P. "Rubber Cylinders under Hydrostatic Pressure with Variable Poisson's Ratio." Rubber Chemistry and Technology 68, no. 4 (September 1, 1995): 585–89. http://dx.doi.org/10.5254/1.3538759.

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Abstract Elastomers are increasingly used in specialized engineering applications where their complex shape often requires a detailed stress analysis. Specialized programmes have to be used for incompressible materials such as elastomers, since the standard computer finite element packages are unable to give accurate solutions for rubbers with Poisson's ratio close to 0.5. The present paper uses an established finite difference method to examine the deflected shape of rubbers under hydrostatic pressure. A particular case of a rubber cylinder subjected to hydrostatic pressure is examined, where a natural tendency is to assume that the rubber cylinder will reduce slightly in volume, evenly all the way round. However, by performing a detailed finite difference analysis, it was found that the final shape, under pressure, was dependent on the value of Poisson's ratio, and height to diameter ratio of the rubber cylinder. An interesting result is that the end of the cylinder, and the circumferential surface will change shape from a concave to a convex surface by changing the value of ν for certain cylindrical shapes of rubber.

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Mahata, Kaushik, Saed Mousavi, and Torsten Söderström. "On the estimation of complex modulus and Poisson's ratio using longitudinal wave experiments." Mechanical Systems and Signal Processing 20, no. 8 (November 2006): 2080–94. http://dx.doi.org/10.1016/j.ymssp.2005.01.006.

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HOSHINO, Yusuke, and Satoru YONEYAMA. "GS0306 Simultaneous Measurement of Complex Modulus and Viscoelastic Poisson's Ratio by Cycling Loading Test." Proceedings of Conference of Kanto Branch 2016.22 (2016): _GS0306–1_—_GS0306–2_. http://dx.doi.org/10.1299/jsmekanto.2016.22._gs0306-1_.

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Mousavi, S., D. F. Nicolas, and B. Lundberg. "Identification of complex moduli and Poisson's ratio from measured strains on an impacted bar." Journal of Sound and Vibration 277, no. 4-5 (November 2004): 971–86. http://dx.doi.org/10.1016/j.jsv.2003.09.053.

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Agbossou, Amen. "An approximate method for the determination of poisson's complex ratio in harmonic viscoelastic behavior." Polymer Composites 16, no. 2 (April 1995): 135–43. http://dx.doi.org/10.1002/pc.750160205.

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Sim, S., and K. J. Kim. "A method to determine the complex modulus and poisson's ratio of viscoelastic materials for FEM applications." Journal of Sound and Vibration 141, no. 1 (August 1990): 71–82. http://dx.doi.org/10.1016/0022-460x(90)90513-y.

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11

Allou, F., M. Takarli, F. Dubois, C. Petit, and J. Absi. "Numerical finite element formulation of the 3D linear viscoelastic material model: Complex Poisson's ratio of bituminous mixtures." Archives of Civil and Mechanical Engineering 15, no. 4 (September 2015): 1138–48. http://dx.doi.org/10.1016/j.acme.2015.02.003.

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12

Salisbury, Matthew H., and David M. Fountain. "The seismic velocity and Poisson's ratio structure of the Kapuskasing uplift from laboratory measurements." Canadian Journal of Earth Sciences 31, no. 7 (July 1, 1994): 1052–63. http://dx.doi.org/10.1139/e94-095.

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The compressional (Vp) and shear (Vs) wave velocity structure of the Kapuskasing uplift have been determined as a function of depth, propagation direction, and polarization from laboratory velocity measurements to confining pressures of 600 MPa on oriented samples from known structural levels of the complex. Based on the relative field abundances of the lithologies measured, the three principal terranes exposed in the uplift are characterized at depth by the following average values of Vp, Vs, and apparent Poisson's ratio, σa: (i) Michipicoten greenstone bell (greenschist, depth 0–6 km, Vp = 6.6 km/s, Vs = 3.9 km/s, σa = 0.235); (ii) Wawa gneiss terrane (amphibolite, depth 6–17 km, Vp = 6.5 km/s, Vs = 3.8 km/s, σa = 0.24); and (iii) Kapuskasing structural zone (granulite, depth 17–23 km, Vp = 6.9 km/s, Vs = 3.9 km/s, σa = 0.27). Although anisotropic lithologies such as paragneiss or mafic gneiss are present at all levels and tend to increase in abundance with depth, only in the deepest level (the Kapuskasing zone) are they sufficiently abundant and oriented to produce significant regional seismic anisotropy (transversely isotropic with Vp and Vs fast in the horizontal plane) and detectable shear wave splitting (ΔVs = 0.1 km/s).A comparison between the laboratory data and velocity models determined for the same crustal section from Lithoprobe refraction studies shows excellent agreement, confirming that the lithologies exposed in the Kapuskasing uplift can be projected downdip to the upper–lower crust transition, or Conrad discontinuity, at about 25 km. Below this depth, high P-wave velocities (7.0–7.6 km/s) suggest that the lower crust is more mafic or garnet rich. Similarities between the velocity structure of the Kapuskasing uplift and other sites in the Canadian Shield suggest that the observed crustal section is fairly typical of Archean continental crust.

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Song, Jianmin, Xianghe Meng, Hao Zhang, Lining Sun, and Hui Xie. "In Situ Quantification the Complex Poisson's Ratio of Single Cells Using a Magnetic-Drive Dynamic Atomic Force Microscopy Approach." IEEE Transactions on Nanotechnology 17, no. 4 (July 2018): 680–83. http://dx.doi.org/10.1109/tnano.2018.2799212.

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Sakai, Yusuke, and Makoto Ohsaki. "Parametric Study of Non-periodic and Hybrid Auxetic Bending-Active Gridshells." Journal of the International Association for Shell and Spatial Structures 61, no. 4 (December 1, 2020): 275–84. http://dx.doi.org/10.20898/j.iass.2020.010.

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This paper presents a design method of Auxetic Bending-Active Gridshells (ABAGs), which are curved surfaces generated from the initial flat grid with 2-dimensional auxetic patterns. One of the mechanical properties of ABAGs is that a dome-like shape of a curved surface can be easily obtained by bending a grid due to negative Poisson's ratio for in-plane deformation. Shapes of auxetic patterns are relevant to Poisson's ratio. Non-periodic and/or hybrid 2-dimensional auxetic patterns are developed for designing the initial flat grid of ABAGs. Shape parameters are the sizes of each plane unit for tuning its reentrant pattern, and two types of reentrant shapes are mixed on an initial flat grid. Using the non-uniform patterns, we can obtain an asymmetric and more complex free-form surface of ABAGs than those composed of a uniform reentrant pattern. Discrete Gaussian curvature at each node on a curved surface is computed for quantitatively evaluating the properties of shapes of the obtained surfaces. Possibility of ABAGs as a new design tool is demonstrated by showing that various shapes are generated through large deformation analysis with the forced displacements at the supports.

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Wang, Jian Ning, Gang Wu, Wei Yi Xie, Xin De Han, and Ming Chao Gang. "Analysis of Packer Rubber Mechanics Properties." Advanced Materials Research 971-973 (June 2014): 380–89. http://dx.doi.org/10.4028/www.scientific.net/amr.971-973.380.

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Abstract: The packer rubber stress in the bottom hole is more complex. Based on constitutive model of the packer rubber material, this paper determines such parameters as model constants, Poisson's ratio of rubber materials and elastic modulus by using experimental method, to build up the finite element model of center tube-rubber cylinder-casing for the purpose of stress analysis. Finally, the distribution regularity of rubber cylinder-casing contact stress and packer setting travel distance with varying loads is concluded. The results can provide the theoretical basis for further analysis of packer rubber sealing performance.

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Subhani, Mahbube, Jian Chun Li, Hauke Gravenkamp, and Bijan Samali. "Effect of Elastic Modulus and Poisson's Ratio on Guided Wave Dispersion Using Transversely Isotropic Material Modelling." Advanced Materials Research 778 (September 2013): 303–11. http://dx.doi.org/10.4028/www.scientific.net/amr.778.303.

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Timber poles are commonly used for telecommunication and power distribution networks, wharves or jetties, piling or as a substructure of short span bridges. Most of the available techniques currently used for non-destructive testing (NDT) of timber structures are based on one-dimensional wave theory. If it is essential to detect small sized damage, it becomes necessary to consider guided wave (GW) propagation as the behaviour of different propagating modes cannot be represented by one-dimensional approximations. However, due to the orthotropic material properties of timber, the modelling of guided waves can be complex. No analytical solution can be found for plotting dispersion curves for orthotropic thick cylindrical waveguides even though very few literatures can be found on the theory of GW for anisotropic cylindrical waveguide. In addition, purely numerical approaches are available for solving these curves. In this paper, dispersion curves for orthotropic cylinders are computed using the scaled boundary finite element method (SBFEM) and compared with an isotropic material model to indicate the importance of considering timber as an anisotropic material. Moreover, some simplification is made on orthotropic behaviour of timber to make it transversely isotropic due to the fact that, analytical approaches for transversely isotropic cylinder are widely available in the literature. Also, the applicability of considering timber as a transversely isotropic material is discussed. As an orthotropic material, most material testing results of timber found in the literature include 9 elastic constants (three elastic moduli and six Poisson's ratios), hence it is essential to select the appropriate material properties for transversely isotropic material which includes only 5 elastic constants. Therefore, comparison between orthotropic and transversely isotropic material model is also presented in this article to reveal the effect of elastic moduli and Poisson's ratios on dispersion curves. Based on this study, some suggestions are proposed on selecting the parameters from an orthotropic model to transversely isotropic condition.

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Jabbari, M., M. Meshkini, and M. R. Eslami. "Mechanical and Thermal Stresses in a FGPM Hollow Cylinder due to Radially Symmetric Loads." ISRN Mechanical Engineering 2011 (October 5, 2011): 1–9. http://dx.doi.org/10.5402/2011/291409.

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The general solution of steady-state on one-dimensional Axisymmetric mechanical and thermal stresses for a hollow thick made of cylinder Functionally Graded porous material is developed. Temperature, as functions of the radial direction with general thermal and mechanical boundary-conditions on the inside and outside surfaces. A standard method is used to solve a nonhomogenous system of partial differential Navier equations with nonconstant coefficients, using complex Fourier series, rather power functions method and solve the heat conduction. The material properties, except poisson's ratio, are assumed to depend on the variable , and they are expressed as power functions of .

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Zhang, Xin Chao, Sam Zan Dong Sun, Hai Yang Wang, Yuan Yin Zhang, Hong Liang Gao, and Bing Jing. "Application of Pre-Stack Inversion to a Complex Reservoir Prediction: a Case Study in LG34 Area, Tarim Basin." Advanced Materials Research 468-471 (February 2012): 624–27. http://dx.doi.org/10.4028/www.scientific.net/amr.468-471.624.

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The Donghe Sandstone formation (DS fm. for simplicity) presents an excellent thin condensate gas reservoir in LG34 well area, Tarim Basin. Unfortunately, drilling results show that the reservoir is thin, deeply buried (below 5000m) and mix lithologies. Pre-stack inversion and fluid identification is implemented in this area. The feasibility and validity of pre-stack inversion for this kind of reservoir is tested, since that application of pre-stack inversion in this area is for the first time. A new rock physics model is used for estimating rock velocities and elastic attributes, and cross-plots of Poisson's ratio (σ) again LambdaRho (λρ) is found to be more favorable for lithofacies identification. Then, pre-stack inversion which uses seismic data with careful amplitude processing is performed to predict the reservoir. The inversion results agree and tie with most wells, suggesting that the pre-stack inversion is viable process for this complex lithological reservoir prediction in the area.

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Vasquez, Guilherme Fernandes, Marcio José Morschbacher, Camila Wense Dias dos Anjos, Yaro Moisés Parisek Silva, Vanessa Madrucci, and Julio Cesar Ramos Justen. "Petroacoustics and composition of presalt rocks from Santos Basin." Leading Edge 38, no. 5 (May 2019): 342–48. http://dx.doi.org/10.1190/tle38050342.1.

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The deposition of the presalt section from Santos Basin began when Gondwana started to break up and South America and Africa were separating. Initial synrift carbonate deposits affected by relatively severe tectonic activity evolved to a lacustrine carbonate environment during the later stages of basin formation. Although the reservoirs are composed of carbonate rocks, the occurrence of faults and the intense colocation of igneous rocks served as a source of chemical elements uncommon in typical carbonate environments. Consequently, beyond the presence of different facies with complex textures and pore geometries, the presalt reservoir rocks present marked compositional and microstructural variability. Therefore, rock-physics modeling is used to understand and interpret the extensive laboratory measurements of P-wave velocities, S-wave velocities, and density that we have undertaken on the presalt carbonate cores from Santos Basin. We show that quartz and exotic clay minerals (such as stevensite and other magnesium-rich clay minerals), which have different values of elastic moduli and Poisson's ratio as compared to calcite and dolomite, may introduce noticeable “Poisson's reflectivity anomalies” on prestack seismic data. Moreover, although the authors concentrate their attention on composition, it will become clear that pore-space geometry also may influence seismic rock properties of presalt carbonate reservoirs.

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Agbossou, A., A. Bergeret, K. Benzarti, and N. Alberola. "Modelling of the viscoelastic behaviour of amorphous thermoplastic/glass beads composites based on the evaluation of the complex Poisson's ratio of the polymer matrix." Journal of Materials Science 28, no. 7 (January 1, 1993): 1963–72. http://dx.doi.org/10.1007/bf00595770.

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Guliyev, H., Kh Aghayev, F. Mehraliyev, and E. Ahmadova. "DETERMINATION OF THE PHYSICAL PROPERTIES OF COMPLEXLY CONSTRUCTED MEDIA USING NEAR-SURFACE CROSSWELL METHOD." Visnyk of Taras Shevchenko National University of Kyiv. Geology, no. 3 (86) (2019): 13–20. http://dx.doi.org/10.17721/1728-2713.86.02.

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In case when the upper part of the medium has complex geological structure and geodynamic processes occur in it, the necessity of these data increases in projecting of the object under construction. Purpose. Studying of acoustic, elastic and anisotropic properties of the upper part of section of complicatedly constructed geological media. Methodology. Seismic observations are conducted in shallow wells in the areas of construction objects located in various seismogeological conditions by NSCW (Near-Surface Cross Well testing) method. Field seismic records are processed. Kinematic and dynamic parameters of pressure and differently polarized shear waves are determined. Thin-layered one-dimensional models of physical properties of the medium are created and interpreted on the basis of nonlinear theory of elastodynamics. Results. It is determined that the medium with high porous, water saturated rocks and anomalous high reservoir pressure has anomalous low value of velocities and gradient of their increase with depth. When this medium was re-examined after deep piles were built there, the overestimated seismic velocities are obtained, which is explained by a decrease in the section of anomalously high reservoir pressure and, accordingly, the porosity of the rocks after piles were built. When the hollowness is increased in unsaturated pebble rocks, the negative value of Poisson's ratio is obtained on the standard method. Seismic anisotropy related with the direction of the grains packing of the rocks is revealed on velocities of shear waves. The change of property of rocks on depth is manifested clearer on frequencies of waves than on their amplitudes. Scientific novelty. The elasticity moduli of the 3rd order are determined which are more sensible to variability of nonlinear elastic properties of rocks of the medium than the moduli of the 2nd order. The values of Poisson's ratio are recalculated for one and the same rocks located in different conditions of rock pressure on the basis of nonclassical theory of deformation. Practical importance. The obtained results can be applied to study the media characterized by complex seismogeological hydrodynamic conditions with clay-sandy rocks of high porosity and water saturation.

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Kitouni, S., and H. Houari. "Lightweight concrete with Algerian limestone dust: Part I: Study on 30% replacement to normal aggregate at early age." Cerâmica 59, no. 352 (December 2013): 600–608. http://dx.doi.org/10.1590/s0366-69132013000400017.

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The mechanical characteristics of the lightweight aggregate concretes (LWAC) strongly depend on the proportions of aggregates in the formulation. In particular, because of their strong porosity, the lightweight aggregates are much more deformable than the cementations matrix and their influence on concrete strength is complex. This paper focuses on studying the physical performance of concrete formulated with substitution of 30% of coarse aggregates by limestone dust. In this article an attempt is made to provide information on the elastic properties of lightweight concrete (LWC) from tests carried out under uniaxial compression conditions. The results of Young modulus, Poisson's ratio, and compressive and flexural tensile strength tests on concrete are presented. The concretes obtained present good mechanical performances reaching 34.99 MPa compressive strength, 6.39 MPa flexural tensile strength and in front of 36 MPa Young modulus.

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Hirano, Tatsumi, Kishio Hidaka, Daiko Takamatsu, Norikazu Takahashi, Keitaro Shishido, Masato Sasaki, and Yuichi Kawashima. "Analysis of Residual Stresses in Pistons of Motor Vehicle Engines Using Neutron Diffraction at J-PARC." Materials Science Forum 772 (November 2013): 27–32. http://dx.doi.org/10.4028/www.scientific.net/msf.772.27.

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Internal residual stresses in the pistons of motor vehicle engines were measured to verify the accuracy of residual stresses estimated by thermal simulations. Coarse crystal grains in aluminum casting alloys frequently make it difficult to measure neutron diffraction profiles if a conventional diffractometer is used for steady reactors [1]. Therefore, the Takumi diffractometer installed at the Japan Proton Accelerator Research Complex (J-PARC), which is a pulse neutron source, was applied to measure them. Residual stresses in pistons determined by the method of neutron diffraction were in good agreement with those estimated through thermal simulations. We concluded from these results that the thermal simulations could be applied to designing and producing pistons. Moreover, Young's modulus and Poisson's ratio for aluminum-silicon casting alloy were determined by using neutron diffraction. We also verified that internal residual stresses could be measured with a tensile sample holder by using the Takumi diffractometer.

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Srivastava, Rajeev, JRP Gupta, and Harish Parthasarathy. "Enhancement and Restoration of Microscopic Images Corrupted with Poisson's Noise Using a Nonlinear Partial Differential Equation-based Filter." Defence Science Journal 61, no. 5 (September 2, 2011): 452. http://dx.doi.org/10.14429/dsj.61.1181.

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An inherent characteristic of the many imaging modalities such as fluorescence microscopy and other microscopic modalities is the presence of intrinsic Poisson noise that may lead to degradation of the captured image during its formation. A nonlinear complex diffusion-based filter adapted to Poisson noise is proposed in this paper to restore and enhance the degraded microscopic images captured by imaging devices having photon limited light detectors. The proposed filter is based on a maximum a posterior approach to the image reconstruction problem. The formulation of the filtering problem as maximisation of a posterior is useful because it allows one to incorporate the Poisson likelihood term as a data attachment which can be added to an image prior model. Here, the Gibb's image prior model-based on energy functional defined in terms of gradient norm of the image is used. The performance of the proposed scheme has been compared with other standard techniques available in literature such as Wiener filter, regularised filter, Lucy-Richardson filter and another proposed nonlinear anisotropic diffusion-based filter in terms of mean square error, peak signal-to-noise ratio, correlation parameter and mean structure similarity index map.The results shows that the proposed complex diffusion-based filter adapted to Poisson noise performs better in comparison to other filters and is better choice for reduction of intrinsic Poisson noise from the digital microscopic images and it is also well capable of preserving edges and radiometric information such as luminance and contrast of the restored image.Defence Science Journal, 2011, 61(5), pp.452-461, DOI:http://dx.doi.org/10.14429/dsj.61.1181

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Kuranovas, Artiomas, and Audronis Kazimieras Kvedaras. "BEHAVIOUR OF HOLLOW CONCRETE‐FILLED STEEL TUBULAR COMPOSITE ELEMENTS." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 13, no. 2 (June 30, 2007): 131–41. http://dx.doi.org/10.3846/13923730.2007.9636429.

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Behaviour of composite steel‐concrete elements in various loading stages is quite well analysed by theoretical investigations and experiments. Concrete‐Filled Steel Tube (CFST) is one of many composite elements used at present in civil engineering. Different approaches and design philosophies were adopted in different design codes for it. But for hollow CFST elements, which are more effective than ordinary CFST, any code does not provide information about how to design these elements. Further investigations of hollow composite CFST elements are needed. In loading stage, when a particular level of stresses exists, an interaction between steel tube and concrete core appears and therefore a complex stress state of element takes place, which increases the load‐bearing capacity of the whole composite element. This interaction between components of CFST elements is reached because of different material properties, such as Poisson's ratio, elasticity modulus etc. In this article reasons of the above‐mentioned complex stress state appearance and behaviour of hollow CFST element components in different load stages of compressed stub structural member are analysed. The test results are presented in diagrams, tables. Previous researches of other investigators are summarised. Differences and similarities in behaviour of solid concrete and composite elements and hollow members with different number of concrete core layers are discussed.

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Peirce, C., A. H. Robinson, M. J. Funnell, R. C. Searle, C. J. MacLeod, and T. J. Reston. "Magmatism versus serpentinization—crustal structure along the 13°N segment at the Mid-Atlantic Ridge." Geophysical Journal International 221, no. 2 (January 29, 2020): 981–1001. http://dx.doi.org/10.1093/gji/ggaa052.

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SUMMARY A region of oceanic core complexes (OCCs) exists at 13°N on the Mid-Atlantic Ridge that is regarded as a type site. This site includes two OCCs at 13°20′N and 13°30′N, thought to be in the active and dying stages of evolution, and two together called the Ashadze Complex (centred at 13°05′N) that are considered to be relict. Here we describe the results of S-wave seismic modelling along an ∼200-km-long 2-D transect traversing, south-to-north, through both the Mercurius and Marathon fracture zones, the southern outside corner of the 13°N segment, the OCCs, the ridge axis deviation in trend centred at 13°35′N, and the youngest oceanic crust of the eastern ridge flank to the north. Our inversion model, and the corresponding Vp/Vs ratio, show that the majority of the crust beneath the 13°30′N OCC comprises metamorphosed lithologies that have been exhumed to the shallowest subseabed level, while basaltic lithologies underlie the 13°20′N OCC. The transition between these contrasting crustal structures occurs over a distance of <5 km, and extends to at least ∼2 km depth below seafloor. The northern and southern OCCs of the Ashadze Complex have contrasting structures at shallow depth, with the northern OCC having a faster S-wave velocity in the upper crust. A Vp/Vs ratio of >1.9 (and equivalent Poisson's ratio of >0.3) indicates exhumed and/or metamorphosed lithologies beneath the bathymetric depression between them and within the crust beneath the southern OCC. Between the northern and southern flanks of the Marathon fracture zone and northern flank of Mercurius fracture zone, the lower crust has a relatively low Vp/Vs ratio suggesting that the deformation associated with Marathon fracture zone, which facilitates fluid ingress, extends laterally within the lower crust. Marathon fracture zone itself is underlain by a broad zone of low S-wave velocity (∼2.0 km s−1) up to ∼20 km wide from the seabed to at least the mid-crust, that is mirrored in a high Vp/Vs ratio and lower density, particularly deeper than ∼1 km below seabed within its bathymetric footprint. Volcanic domains are highlighted by a low Vp/Vs ratio of <1.6 (and equivalent Poisson's ratio of <0.15). Our combined seismic and density models favour the localized model of OCC evolution. They also show a considerable ridge-parallel variability in the amount and distribution of magmatic versus metamorphosed crust. Our results suggest that the current focus of magmatism lies to the north of the 13°20′N OCC, where the magmatic accretion-type seabed morphology observed is mirrored in the pattern of microseismicity, suggesting that its inward-facing median-valley-wall fault may link to the 13°20′N OCC detachment surface. Magmatism and active faulting behind (to the west) the footwall breakaway of the 13°30′N OCC, and the microseismicity concentrated in a band along its southern flank, suggest a readjustment of ridge geometry along axis is underway. As part of this, a transform offset is forming that will ultimately accommodate the 13°30′N OCC in its inside corner on the eastern flank of the ridge axis to the north.

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Calvert, A. J., and R. M. Clowes. "Seismic evidence for the migration of fluids within the accretionary complex of western Canada." Canadian Journal of Earth Sciences 28, no. 4 (April 1, 1991): 542–56. http://dx.doi.org/10.1139/e91-048.

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Multichannel deep seismic reflection data from the subduction zone of western Canada delineate the wedge of accereted sediments and the principal terranes (Crescent, Pacific Rim, and Wrangellia) that form the convergent margin. The top of the igneous oceanic crust is defined by subhorizontal reflections extending at least 100 km landward of the deformation front. Upon incorporation into the accretionary wedge, the clearly defined stratigraphy of the incoming oceanic sedimentary section is destroyed over a distance of about 10 km. Initially, an unreflective zone, which correlates well with maximum fluid expulsion, is formed. Farther landward, a predominantly landward-dipping reflectivity exists. A number of reflections are thrust faults, which appear to merge at depth with the subhorizontal reflections, but most have another origin. These reflections may be related to the movement of fluids generated by the compaction of sediments or possibly by the dehydration of the subducting plate. They are strongest in a region of depressed seismic velocities beneath the continental slope, where an analysis of reflection amplitude with offset implies that a high Poisson's ratio exists; this is consistent with the presence of elevated pore pressures. Thus, pore pressure variations associated with the migration of fluids may be the cause of much of the reflectivity within the accreted wedge, although the precipitation of minerals from rising fluids could also be important. Evidence from the seismic data also indicates that fluids from the accretionary prism are being expelled into the sediments of the overlying Tofino basin. A number of anomalously strong reflections and disruption of the horizontally stratified sediments within the lower levels of the basin probably represent fluids that migrated upward from the accreted wedge and were trapped against impermeable barriers created through the deposition of sediments on the continental slope and in the basin.

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Gil, Enrique, Jose Vercher, Carlos Lerma, Ángeles Mas, and Quiteria Angulo. "Constitutive Laws Assessment for Unconfined Concrete under Compression." Applied Mechanics and Materials 861 (December 2016): 137–40. http://dx.doi.org/10.4028/www.scientific.net/amm.861.137.

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Nowadays, the rehabilitation of buildings takes more importance due to sustainability reasons. This involves working with existing building structures and the precise calculus of the building to guarantee the adequate strength and safety, from structures with change of use to deteriorated or damaged structures. Concrete is the most common material in building structures, but it is a heterogeneous and non-linear material. The concrete constitutive law, relation between strains and stresses in different directions, is very complex, and different in tension and compression. In the case of new construction project, the linear relationship between stress and strain has been proved safe enough, but it is unable to simulate the behaviour of used and damaged structures, where it is necessary to study the entire load range. In this work, the most widely used constitutive laws of concrete are compared, parameterizing the necessary constants for their professional application in advanced simulation structures software. Some of the evaluated constants are the Young's modulus, Poisson's ratio, stress cracking and crushing, failure energy or the law of damage evolution. Linear-multilinear behaviour, Willam-Warnke crushing and cracking criteria, continuum damage and microplane options are the assessed constitutive laws, showing the differences between the behaviour models and the tightest values of these material constants along the entire load range.

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Altawati, Faisal, Hossein Emadi, and Rayan Khalil. "An experimental study to investigate the physical and dynamic elastic properties of Eagle Ford shale rock samples." Journal of Petroleum Exploration and Production Technology 11, no. 9 (July 26, 2021): 3389–408. http://dx.doi.org/10.1007/s13202-021-01243-w.

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AbstractUnconventional resources, such as Eagle Ford formation, are commonly classified for their ultra-low permeability, where pore sizes are in nano-scale and pore-conductivity is low, causing several challenges in evaluating unconventional-rock properties. Several experimental parameters (e.g., diffusion time of gas, gas injection pressure, method of permeability measurement, and confining pressure cycling) must be considered when evaluating the ultra-low permeability rock's physical and dynamic elastic properties measurements, where erroneous evaluations could be avoided. Characterizing ultra-low permeability samples' physical and elastic properties helps researchers obtain more reliable information leading to successful evaluations. In this study, 24 Eagle Ford core samples' physical and dynamic elastic properties were evaluated. Utilizing longer diffusion time and higher helium injection pressure, applying complex transient method, and cycling confining pressure were considered for porosity, permeability, and velocities measurements. Computerized tomography (CT) scan, porosity, permeability, and ultrasonic wave velocities were conducted on the core samples. Additionally, X-ray Diffraction (XRD) analysis was conducted to determine the mineralogical compositions. Porosity was measured at 2.07 MPa injection pressure for 24 h, and the permeability was measured using a complex transient method. P- and S-wave velocities were measured at two cycles of five confining pressures (up to 68.95 MPa). The XRD analysis results showed that the tested core samples had an average of 81.44% and 11.68% calcite and quartz, respectively, with a minor amount of clay minerals. The high content of calcite and quartz in shale yields higher velocities, higher Young's modulus, and lower Poisson's ratio, which enhances the brittleness that is an important parameter for well stimulation design (e.g., hydraulic fracturing). The results of porosity and permeability showed that porosity and permeability vary between 5.3–9.79% and 0.006–12 µD, respectively. The Permeability–porosity relation of samples shows a very weak correlation. P- and S-wave velocities results display a range of velocity up to 6206 m/s and 3285 m/s at 68.95 MPa confining pressure, respectively. Additionally, S-wave velocity is approximately 55% of P-wave velocity. A correlation between both velocities is established at each confining pressure, indicating a strong correlation. Results illustrated that applying two cycles of confining pressure impacts both velocities and dynamic elastic moduli. Ramping up the confining pressure increases both velocities owing to compaction of the samples and, in turn, increases dynamic Young's modulus and Poisson's ratio while decreasing bulk compressibility. Moreover, the results demonstrated that the above-mentioned parameters' values (after decreasing the confining pressure to 13.79 MPa) differ from the initial values due to the hysteresis loop, where the loop is slightly opened, indicating that the alteration is non-elastic. The findings of this study provide detailed information about the rock physical and dynamic elastic properties of one of the largest unconventional resources in the U.S.A, the Eagle Ford formation, where direct measurements may not be cost-effective or feasible.

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Sun, Chengyu, Zhinong Wang, Dunshi Wu, Ruiqian Cai, and Han Wu. "A unified description of surface waves and guided waves with relative amplitude dispersion maps." Geophysical Journal International 227, no. 3 (August 16, 2021): 1480–95. http://dx.doi.org/10.1093/gji/ggab284.

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SUMMARY Compared with surface waves, guided waves are rarely applied in near-surface investigation. The main reason may lie in the complexity of their dispersion curves. Besides, the study and understanding of guided wave dispersion characteristics are now also inadequate and not deep enough. In this paper, we derived the complete theoretical dispersion curves of P–SV-wave and pure P-wave systems in layered media based on the transmission matrix method and obtained the relative displacement amplitude coefficients at the free surface as a function of frequency and phase velocity for both surface and guided waves. By assigning the value of relative displacement amplitude coefficient to the corresponding point (f,v) on dispersion curve, we got a multi-information diagram called relative amplitude dispersion map (RADM). As a unified description of surface and guided waves, RADM not only shows the velocity–frequency relationship but also represents the polarized energy ratio at the free surface by display colours. The accuracy of RADM was proved by synthetic seismic records, in which RADMs fit well with the corresponding dispersion energy of surface and guided waves. In addition, we designed six models with different Poisson's ratio (PR) and different layer numbers for comparison. It shows that the dispersive vertical-to-horizontal amplitude ratio of guided waves is complex and discontinuous in RADM, which brings great difficulty for mode identification and even affects the subsequent inversion. Tests also show that for high PR layers, the trends of guided P–SV-wave dispersion curves are basically consistent with those of pure P wave. With the decrease of PR, dispersion curves of guided P–SV wave gradually deviate from those of pure P wave. However, RADMs can be greatly consistent with the dispersion energy in either case. This is of great significance for the inversion of near-surface P and S velocities by using dispersion relationships of multimode surface and guided waves.

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Tezuka, Ken-Ichi, Akiyuki Takahashi, Tomoko Takeda, Yoshitaka Wada, and Masanori Kikuchi. "Computer Simulation of Human Mandibular Bone Structure by iBone, a Novel Reaction-Diffusion Bone Remodeling Model." Key Engineering Materials 306-308 (March 2006): 1277–82. http://dx.doi.org/10.4028/www.scientific.net/kem.306-308.1277.

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Bone is a complex system with adaptation and repair functions. To understand how bone cells can create a structure adapted to the mechanical environment, we proposed a simple bone remodeling model, iBone, based on a reaction-diffusion system [1]. A 3-dimensional mandibular bone model consisting of approximately 1.4 million elements was constructed from sequential computer tomography (CT) images of a 14-year old female. Both teeth and bone were modeled with isoparametric voxel elements with Young's Modulus = 20 GPa and Poisson's ratio = 0.3. Both heads of the mandible were fixed allowing rotation and horizontal movement. Teeth were fixed vertically allowing horizontal movements. Incisor, right/left group, and right/left molar biting conditions were simulated. The locations and directions of muscles, and their forces were predicted from the CT images. Remodeling simulation was performed by 10 sets of finite element method analysis and reaction-diffusion remodeling simulation to obtain internal structure adapted to each loading condition. As a result, the major part of the corpus of the simulated mandibular bone showed similar internal structures under different biting conditions. Moreover, these simulated structures were satisfactorily similar to that of the real mandible. Computer simulation of three-dimensional bone structures based on CT images will be very useful for understanding the patho-physiological state of bone under various mechanical conditions, and may assist orthopedic doctors to predict the risk and efficacy of surgical therapies.

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Stephen, N. G. "Transfer matrix analysis of the elastostatics of one-dimensional repetitive structures." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 462, no. 2072 (February 28, 2006): 2245–70. http://dx.doi.org/10.1098/rspa.2006.1669.

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Transfer matrices are used widely for the dynamic analysis of engineering structures, increasingly so for static analysis, and are particularly useful in the treatment of repetitive structures for which, in general, the behaviour of a complete structure can be determined through the analysis of a single repeating cell, together with boundary conditions if the structure is not of infinite extent. For elastostatic analyses, non-unity eigenvalues of the transfer matrix of a repeating cell are the rates of decay of self-equilibrated loading, as anticipated by Saint-Venant's principle. Multiple unity eigenvalues pertain to the transmission of load, e.g. tension, or bending moment, and equivalent (homogenized) continuum properties, such as cross-sectional area, second moment of area and Poisson's ratio, can be determined from the associated eigen- and principal vectors. Various disparate results, the majority new, others drawn from diverse sources, are presented. These include calculation of principal vectors using the Moore–Penrose inverse, bi- and symplectic orthogonality and relationship with the reciprocal theorem, restrictions on complex unity eigenvalues, effect of cell left-to-right symmetry on both the stiffness and transfer matrices, eigenvalue veering in the absence of translational symmetry and limitations on possible Jordan canonical forms. It is shown that only a repeating unity eigenvalue can lead to a non-trivial Jordan block form, so degenerate decay modes cannot exist. The present elastostatic analysis complements Langley's (Langley 1996 Proc. R. Soc. A 452 , 1631–1648) transfer matrix analysis of wave motion energetics.

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Mereu, R. F. "The complexity of the crust and Moho under the southeastern Superior and Grenville provinces of the Canadian Shield from seismic refraction - wide-angle reflection data." Canadian Journal of Earth Sciences 37, no. 2-3 (April 2, 2000): 439–58. http://dx.doi.org/10.1139/e99-122.

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The major features of the individual velocity models, Poisson's ratio values, and crustal complexity derived from the interpretation of seismic data sets from four long-range seismic refraction - wide-angle reflection experiments are summarized. The experiments were conducted from 1982-92 in the southeastern portion of the Canadian Shield. In the conventional analysis of seismic refraction - wide-angle reflection data, only the onset times and amplitudes of the major arrival phases are used to derive seismic velocity models of the region under study. These models are over smoothed, have a number of intermediate discontinuities, are unable to explain the Pg coda, and bear very little resemblance to the models derived from the analysis of near-vertical seismic reflection data. In this paper some of the differences between seismic models derived from near-vertical reflection analysis and those from refraction analysis are reconciled from an analysis of the wide-angle reflection fields of the crustal coda waves that follow the first arrivals. This was done using a migration technique that to a first approximation maps the amplitudes of the record sections into a two-dimensional (2-D) complexity section. These new sections show significant lateral variations in crustal and Moho reflectivity and may be used to complement the 2-D velocity anomaly sections and near-vertical reflection sections. The method was based on a numerical study that showed that the coda can be explained with a class of complex heterogeneous models in which sets of small-scale, high-contrast sloping seismic reflectors are "embedded" in a uniform seismic velocity gradient field.

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Baykov, A. V., R. A. Turusov, A. N. Trofimov, and L. V. Pleshkov. "NUMERICAL SIMULATION OF THE ELASTIC BEHAVIOR OF SYN-CYCLE COMPOSITES BASED ON HOLLOW GLASS MICROSPHERES UNDER TENSION." Problems of strenght and plasticity 83, no. 1 (2021): 22–34. http://dx.doi.org/10.32326/1814-9146-2021-83-1-22-34.

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Using the universal software package “Solid Works”, on the example of a cubic model of a composite based on hollow glass microspheres (HGM), numerical simulation of the elastic behavior of a syntactic material under uniaxial tension is carried out. The chosen computational model is a hollow thin-walled glass sphere placed in a polymer (epoxy) matrix of cubic shape. The model was calculated using the finite-element method in an elastic approach with boundary conditions defined by the used universal software system of 3D modeling of the “Solid Works” complex. The calculations made it possible to determine the longitudinal and transverse elastic strains for the model of a syntactic composite with different contents of the initial components and then to calculate the value of the elastic modulus and the Poisson's ratio under tension for these materials. Experimental verification of the calculations performed was carried out on samples of syntactic composites based on epoxy binder and HGM of type MC-ВП A9 2 gr. A size group of microspheres with a diameter of 50 to 70 microns was isolated from the initial HGM by sieving method. The average diameter of these microspheres was about 59 microns. On the basis of the microspheres selected in this way, samples of epoxy composites with different volume contents of components (30%, 40% and 50% HGM) were made and their actual elastic characteristics under tension were measured. The results of experiments to determine the elastic characteristics of syntactic composites correlate well with the calculations, especially for composites with a filling coefficient of 0.45–0.5 with hollow microspheres.

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Ondruška, Juraj, Ľubomír Šooš, Iveta Onderová, and Viliam Čačko. "Feedback FEM Analysis to the Material Properties in the Simulation of Radial Pressure in the Cylindrical Chamber." Applied Mechanics and Materials 832 (April 2016): 213–17. http://dx.doi.org/10.4028/www.scientific.net/amm.832.213.

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An article is about mechanical effect of the physic-mechanical material properties on the radial pressure in the compression chamber during the compacting process of wood. Some general methods that describe the transformation process of axial pressure into the radial pressure are shown, As well as the mathematical or experimental methods specifying dependencies and physical conditions. Mathematical finite element method in this area is very useful, but rarely used. Common problems using FEM are the proper definition of the physical material properties in a particular stage of compaction. Material properties are greatly influenced by a number of factors such as moisture, fraction size, chemical composition, current temperature, radial macro structure, axial macrostructure, current pressure and others. The chamber material and the manufacturing processes or the state of wear has an impact on the physical conditions. In terms of tensile elastic deformations, these complex effects reflect and can be merged into several properties. The conversion of axial to radial pressure indicates that some properties of the compacted material have a major impact on the process, such as friction between material and chamber, elastic modulus and Poisson's ratio. The geometry of the pressing chamber also has a significant impact. This paper does not deal so much with the pressing chamber geometry but more so with the characteristics embodied in experimentally measurable quantities. The measurement of these properties in combination with the application of FEM methods proves to be a highly progressive method for understanding the compaction process and the engineering design of compaction machines for the production of briquettes and pellets. The article urges further examination and measurement of a wider range of material properties in the densification process.

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Graziani, Andrea, Maurizio Bocci, and Francesco Canestrari. "Complex Poisson’s ratio of bituminous mixtures: measurement and modeling." Materials and Structures 47, no. 7 (June 18, 2013): 1131–48. http://dx.doi.org/10.1617/s11527-013-0117-2.

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Al-Tahini, Ashraf M., Carl H. Sondergeld, and Chandra S. Rai. "The Effect of Cementation on the Mechanical Properties of Sandstones." SPE Reservoir Evaluation & Engineering 9, no. 04 (August 1, 2006): 308–16. http://dx.doi.org/10.2118/89069-pa.

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Summary The variability in mechanical properties measured on sands from the Jauf and Unayzah formations of Saudi Arabia is observed to be dependent upon cementation. Understanding the role of cementation in controlling the mechanical properties can improve the design of hydraulic-fracture treatments and, hence, improve reservoir performance. Strength measurements from triaxial-testing data and examination of core in thin sections were used to relate the detailed microstructure and cementation to the variation of mechanical properties. Strength and elastic moduli were determined for 65 samples cored from five different wells. Forty-seven samples were analyzed in thin sections and point counted to determine and quantify cementation. Cements in these two formations have variable composition and habits; both affect the mechanical properties and strength. It is not sufficient to know that cements exist; it is also necessary to know where the cement occurs. Pure quartz over growths play a major role in increasing strength, while clay coatings play a minor role. Simple linear correlations were found relating cement concentrations to strength. Introduction The Jauf and Unayzah reservoirs (Ghawar field, Saudi Arabia) are deep sequences of thin sandstones and shales saturated with condensate-rich gas. These reservoir rocks display a wide variation in both permeability and porosity (Fig. 1) (Al-Qahtani and Buhidma 2001). Hydraulic fracturing has been introduced to enhance productivity in the Jauf sandstones within the Ghawar reservoir. The complex nature of tectonic stresses, geomechanical properties, and geology leads to problems of sand production and wellbore stability in the Unayzah and Jauf formations. Such problems make the development of these reservoirs challenging. The variations of mechanical properties such as Young's modulus (E), Poisson's ratio, (u), and unconfined compressive strength (UCS) have a direct impact on hydraulic-fracture design. The variation of these properties affects fracture propagation and geometry and, consequently, gas production.

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Guillot, François M., and D. H. Trivett. "Experimental determination of the complex Poisson’s ratio of viscoelastic materials." Journal of the Acoustical Society of America 129, no. 4 (April 2011): 2613. http://dx.doi.org/10.1121/1.3588678.

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Gudmarsson, Anders, Nils Ryden, Hervé Di Benedetto, and Cédric Sauzéat. "Complex modulus and complex Poisson’s ratio from cyclic and dynamic modal testing of asphalt concrete." Construction and Building Materials 88 (July 2015): 20–31. http://dx.doi.org/10.1016/j.conbuildmat.2015.04.007.

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Pritz, Tamás. "Bounds on the imaginary part of complex Poisson’s ratio of viscoelastic materials." Journal of the Acoustical Society of America 146, no. 4 (October 2019): 2882. http://dx.doi.org/10.1121/1.5136998.

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Carneiro, Vitor, and Helder Puga. "Temperature Variability of Poisson’s Ratio and Its Influence on the Complex Modulus Determined by Dynamic Mechanical Analysis." Technologies 6, no. 3 (August 23, 2018): 81. http://dx.doi.org/10.3390/technologies6030081.

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Dynamic mechanical analysis (DMA) is the usual technology for the thermomechanical viscoelastic characterization of materials. This method monitors the instant values of load and displacement to determine the instant specimen stiffness. Posteriorly, it recurs to those values, the geometric dimensions of the specimen, and Poisson’s ratio to determine the complex modulus. However, during this analysis, it is assumed that Poisson’s ratio is constant, which is not always true, especially in situations where the temperature can change and promote internal modification in the specimens. This study explores the error that is imposed in the results by the determination of the real values of complex moduli due to variable Poisson’s ratios arising from temperature variability using a constant frequency. The results suggest that the evolution of the dynamic mechanical analysis should consider the Poisson’s ratio input as a variable to eliminate this error in future material characterization.

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Brnada, Snježana, Željko Šomođi, and Stana Kovačević. "A new method for determination of Poisson’s ratio of woven fabric at higher stresses." Journal of Engineered Fibers and Fabrics 14 (January 2019): 155892501985622. http://dx.doi.org/10.1177/1558925019856225.

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Determination of Poisson’s ratio and shear module of complex, nonlinear elastic material, such as woven fabric, is a challenge for researchers in the field of textile mechanics. In the standard method of determining the Poisson’s ratio, the transverse fabric strain is measured by a 1% tensile extension. In this way, there is no information about changing the Poisson’s ratio at higher tensile extensions, and the methodology itself is unsuitable for larger extensions because of woven fabric buckling. In this research, a device has been designed, which can be built on a dynamometer and which has the ability to measure transverse forces in fabric during tensile test. A mechanical model is developed from which it is possible to calculate Poisson’s ratio throughout the fabric stress–strain curve.

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Ahmed, Ashraf, Salaheldin Elkatatny, and Ahmed Alsaihati. "Applications of Artificial Intelligence for Static Poisson’s Ratio Prediction While Drilling." Computational Intelligence and Neuroscience 2021 (May 4, 2021): 1–10. http://dx.doi.org/10.1155/2021/9956128.

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The prediction of continued profile for static Poisson’s ratio is quite expensive and requires huge experimental works, and the discontinuity in the measurement and the limited applicability and accuracy of the present empirical correlations necessitated the utilization of artificial intelligence with its prosperous application in oil and gas industry. This work aims to construct different artificial intelligence models for predicting static Poisson’s ratio of complex lithology at real time during drilling. The functional networks (FN) and random forest (RF) approaches were utilized using the mechanical drilling parameters as inputs. This study uses a vertical well with 1775 records from complex lithology containing shale, sand, and carbonate for model building. Besides, a different dataset from another well was used to check the models’ validity. The results demonstrated that both FN- and RF-based models predicted static Poisson’s ratio with significant matching accuracy. The FN technique results’ correlation coefficient (R) value of 0.89 and average absolute percentage error (AAPE) values of 10.23% and 10.28% in training and testing processes. While the RF technique is outperformed, as illustrated by the highest R values of 0.99 and 0.94 and the lowest AAPE values of 1.89% and 5.19% for training and testing processes, the robustness and reliability of the developed models were confirmed in the validation process with R values of 0.94 and 0.86 and AAPE values of 11.23% and 5.12% for FN- and RF-based models, respectively. The constructed models developed a basis for inexpensive static Poisson’s ratio prediction in real time with significant accuracy.

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Liu, Sai, Xingxing Pan, Dongming Zheng, Zhaoqun Du, Gui Liu, and Shu Yang. "Study on the structure formation and heat treatment of helical auxetic complex yarn." Textile Research Journal 89, no. 6 (March 12, 2018): 1003–12. http://dx.doi.org/10.1177/0040517518760754.

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Currently, auxetic yarns consisting of a core filament and a wrap filament are generally utilized as complex materials, which are attributed to residual torque. Thus, the main content dealt with in this paper was to analyze the structure formation and effect of heat treatment of helical auxetic complex yarn spun by a modified ring-spinning system. Firstly, an orthogonal experiment with three factors and three levels was carried out to study the effects of diameter ratio, yarn twists and initial helical angle on the structure and Poisson’s ratio of complex yarn. Secondly, a heat treatment process with polyamide filament with low melting point (80℃) was conducted to improve the structural stability of auxetic complex yarn. It was found that the heat treatment process can not only improve the structural stability of complex yarn, but also promote the expansion effect. By comparing experimental and theoretical results, it was found that the variation of Poisson’s ratio with axial strain had good consistency. Therefore, the heat treatment method can effectively solve the slippage problem of helical auxetic complex yarn.

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Sheiba, L. "Method for broadband measurement of complex shear modulus and Poisson ratio of viscoelastic materials." Journal of the Acoustical Society of America 102, no. 5 (November 1997): 3067. http://dx.doi.org/10.1121/1.419542.

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Shevchuk, T. M., M. A. Bordyuk, V. V. Krivtsov, V. V. Kukla, and V. A. Mashchenko. "Viscoelastic Properties of Filled Polyurethane Auxetics." Physics and Chemistry of Solid State 22, no. 2 (June 16, 2021): 328–35. http://dx.doi.org/10.15330/pcss.22.2.328-335.

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The paper presents experimental values of lateral and extension transmission ultrasonic waves speed and their absorbance coefficient obtained with the help of discrete immersed method in metal filled polymer auxetic samples with polyurethane matrix. Poisson’s ratio, real and imaginary parts of complex dynamic elastic modulus (Young’s modulus, shear modulus, bulk modulus) and mechanical losses tangent of angle for extension, lateral and bulk deformation have been calculated regarding paper’s results. Viscoelastic properties of polyurethane auxetic have been examined regarding different theoretical approaches. To support negative values of Poisson’s ratio, a filled polymer model with critical filler amount and auxetic deformation models have been used. Models structural characteristics for filled polyurethane auxetics have been defined. Systems modeling with solid bulky inclusions, that are able to absorb and to disseminate ultrasonic waves, enables to consider suchlike systems as complex density materials. It is shown that in certain ratio of wave parameters and environment structural and mechanical properties, resonance effects take place, regarding filler’s particles vibration as inclusions in general.

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Xie, Qingge, Junhe Lian, Fengwei Sun, Bin Gan, and Yandong Wang. "The lattice strain ratio in characterizing the grain-to-grain interaction effect and its specific insight on the plastic deformation of polycrystalline materials." Journal of Strain Analysis for Engineering Design 53, no. 5 (April 24, 2018): 353–63. http://dx.doi.org/10.1177/0309324718770935.

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A single grain can contract or expand in the transverse direction when it is stretched. It becomes complex when the single grain is embedded in a stretched polycrystal, due to the grain neighborhood effect, which can outweigh the lateral contraction/expansion of that grain itself. Here, we performed numerical simulations to elucidate such grain-to-grain interaction effects on the lattice strain behavior. For individual grains in a polycrystal, pseudo Poisson’s ratio is defined. Ratios of Poisson’s ratio over pseudo Poisson’s ratio were employed to indicate the difference between the cases of the grain deformation with and without the constraint imposed from the neighboring grains. The high-stress spots and the sense of the stress components can be identified with a high possibility according to the proposed ratios. Most of the identified high-stress spots feature tensile stresses in three directions, while some of them feature the compressive stress in one transverse direction and a negative Poisson’s ratio. For the latter, a strong grain-to-grain interaction during the plastic stage of deformation is found. These grains induce the reversal of the lattice strain evolution curve for the measured <002>//TD, which is often found in the literature and in the data of neutron diffraction.

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Nguyen, Quang Tuan, Hervé Di Benedetto, Quang Phuc Nguyen, Thi Thanh Nhan Hoang, and Van Phu Bui. "Effect of time–temperature, strain level and cyclic loading on the complex Poisson’s ratio of asphalt mixtures." Construction and Building Materials 294 (August 2021): 123564. http://dx.doi.org/10.1016/j.conbuildmat.2021.123564.

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Davarpanah, M., G. Somodi, L. Kovács, and B. Vásárhelyi. "Complex analysis of uniaxial compressive tests of the Mórágy granitic rock formation (Hungary)." Studia Geotechnica et Mechanica 41, no. 1 (April 12, 2019): 21–32. http://dx.doi.org/10.2478/sgem-2019-0010.

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AbstractUnderstanding the quality of intact rock is one of the most important parts of any engineering projects in the field of rock mechanics. The expression of correlations between the engineering properties of intact rock has always been the scope of experimental research, driven by the need to depict the actual behaviour of rock and to calculate most accurately the design parameters. To determine the behaviour of intact rock, the value of important mechanical parameters such as Young’s modulus (E), Poisson’s ratio (ν) and the strength of rock (σcd) was calculated. Recently, for modelling the behaviour of intact rock, the crack initiation stress (σci) is another important parameter, together with the strain (σ). The ratio of Young’s modulus and the strength of rock is the modulus ratio (MR), which can be used for calculations. These parameters are extensively used in rock engineering when the deformation of different structural elements of underground storage, caverns, tunnels or mining opening must be computed. The objective of this paper is to investigate the relationship between these parameters for Hungarian granitic rock samples. To achieve this goal, the modulus ratio (MR = E/σc) of 50 granitic rocks collected from Bátaapáti radioactive waste repository was examined. Fifty high-precision uniaxial compressive tests were conducted on strong (σc >100 MPa) rock samples, exhibiting the wide range of elastic modulus (E = 57.425–88.937 GPa), uniaxial compressive strength (σc = 133.34–213.04 MPa) and Poisson’s ratio (ν = 0.18–0.32). The observed value (MR = 326–597) and mean value of MR = 439.4 are compared with the results of similar previous researches. Moreover, the statistical analysis for all studied rocks was performed and the relationshipbetween MR and other mechanical parameters such as maximum axial strain $\left( {{\varepsilon }_{\text{a,}\,\text{max}}} \right)$for studied rocks was discussed.

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Yuan, Qianqian, Yongsheng Zhu, Ke Yan, Yiqing Cai, and Jun Hong. "Negative Poisson’s Ratio-Spacer Design and Its Thermo-Mechanical Coupling Analysis Considering Specific Force Output." Materials 14, no. 12 (June 21, 2021): 3421. http://dx.doi.org/10.3390/ma14123421.

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Aiming at the problems of a complex structure or poor controllability of the existing bearing preload control devices, a method of self-regulation via a negative Poisson’s ratio (NPR) spacer is proposed. Firstly, the principle of preload automatic adjustment at the bearing operation was introduced and the NPRs with three types of cell structures were analyzed. Furthermore, a thermo-mechanical coupling analysis model of the NPR spacer was established and the deformation and force output characteristics of the NPR spacer were studied and experimentally verified. It is found that the concave hexagonal cell structure has the optimal deformation characteristics for bearing preload adjustment. When the temperature is considered, the absolute value of Poisson’s ratio of the NPR spacer decreases as the speed increases and the elongation of the NPR spacer and the output forces are much larger than those without temperature consideration. With the increase in temperature or rotating speed, the axial elongation and output forces of the NPR spacer increases while the effect of temperature is relatively larger.

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Journal articles on the topic 'Complex Poisson's ratio'

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