### Young s modulus and Poisson s ratio changes due to

Jul 25 2016 · Dunn ML Ledbetter H (1995) Poisson s ratio of porous and microcracked solids theory and application to oxide superconductors. J Mater Res 10(11) 2715–2722 Article materials with a negative Poisson s ratio. They expand in all directions when only pulled in one. In this paper the acoustic properties of auxetic foams are A porous material consists of a solid phase which is the frame or Biot s theory describes the propagation of waves through porous media.

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materials with a negative Poisson s ratio. They expand in all directions when only pulled in one. In this paper the acoustic properties of auxetic foams are A porous material consists of a solid phase which is the frame or Biot s theory describes the propagation of waves through porous media. Jul 25 2016 · Dunn ML Ledbetter H (1995) Poisson s ratio of porous and microcracked solids theory and application to oxide superconductors. J Mater Res 10(11) 2715–2722 Article

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Oct 12 2016 · The coupling between deformations along the sample s loading and its lateral directions is governed by the Poisson s ratio which is defined as the negative ratio of the lateral normal strain to We present a theoretical study of the effective Poisson s ratio of elastic solids weakened by porosity and microcracks. Explicit expressions of the effective Poisson s ratio are obtained using the Mori-Tanaka mean-field approach as applied to macroscopically isotropic solids containing randomly distributed and randomly oriented spheroidal pores.

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Aug 01 2017 · In porous media the bulk Poisson s ratio is lower than the grain material due to the compressibility of the pores. Poisson s ratio of porous and microcracked solids theory and application to oxide superconductors. J. Mater. Res. 10 (1995) pp. . View Record in Ledbetter H. and Lei M. (1991) Poisson s Ratio of Porous and Microcracked Solids Bandaj ile Sarılmış yara İltihaplanmış Yara Şişer Yara İyileşir Theory and Application to Oxide Superconductors Journal of Materials Research 6 2253–2255.

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ABSTRACT Poisson s ratio is determined by two independent factors i.e. the solid rock and dry or wet cracks. The former is influenced by the constituent mineral composition. The higher Poisson s ratio of the rock solid is the higher is Poisson s ratio of the rock. unchanged. This dependence of Poisson s ratio on crack aspect ratio was previously noted by Hyndman (1979). Figure 3 illustrates the increase in Poisson s ratio for a thin-cracked material (d = 0.001) as a function of porosity while Fig. 4 shows the decrease in Poisson s ratio for a thick-cracked material (d = 0.1). Note the difference in

Get Price### P-SV wave propagation in heterogeneous media Velocity

P-wave velocity of 6 000 m/s the P-wave half-wavelength is 1 800 m and the S-wave half-wavelength is 1 000 m for a Poisson s ratio v = 0.25. Consequently a good choice for the grid spacing is around 100 m. t is chosen to give a causal signal which is approximately zero for negative time In materials science and solid mechanics Poisson s ratio is a measure of the Poisson effect the deformation (expansion or contraction) of a material in directions perpendicular to the specific direction of loading.The value of Poisson s ratio is the negative of the ratio of transverse strain to axial strain.For small values of these changes is the amount of transversal elongation divided by

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Oct 10 2018 · From the elastic model Poisson s ratios of 0.34 0.38 or 0.42 (i.e. V p /V s of 2.03 2.27 or 2.69) are uniquely related to values of crack density ρ and intrinsic Poisson s ratio (Figure 3). Permeability could thus be directly inferred as qualitatively attempted here (Figure 4 ) by assuming realistic values of w = 0.7 μm and ξ = 5 10 cracked solid can be obtained by () ()()() 0 0 11 1 22 2 k k ij ij ijkl kl ij ijkl kl i ij j k ij PM M nbs V PP σσσσσ σ σ == = Δ ∑ (8) where P0 ()σij is the potential of a matrix material without cracks which has the following expression for an isotropic (no crack) material with Young s modulus E0 and Poisson s ratio

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any other effective medium theory such as the Mori–Tanaka or Kuster–Toksoz schemes. The relatively simple expressions found for the various effective medium schemes as well as the bounds found for the effective Poisson s ratio will be useful to simplify the process of inversion of elastic velocities in porous solids. 2011 Elsevier Ltd. A rigorous stable fixed-point is obtained for Poisson s ratio ν c of dry porous media where the location of this fixed-point depends only on the shape of the voids being added. Fixed-points occur at for spheres and ν c ≃πα/18 for cracks where α is the aspect ratio of penny-shaped cracks.

Get Price### Geometry The leading parameter for the Poisson s ratio of

ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT Geometry The leading parameter for the Poisson s ratio of bending-dominated cellular solids Holger Mitschke a Fabian Schury b Klaus Mecke a Fabian Wein b Michael Stingl b Gerd E. Schröder-Turk c a Theoretische Physik I Friedrich-Alexander-Universität Erlangen-Nürnberg Staudtstr. 7B 91058 Erlangen Germany International Journal of Solids and Structures Elsevier 2016 81 pp.63-83. This model relies on the coupling between Gri th s theory and homogenization methods Overall estimates of Cecchi Taliercio model are softer than the Cecchi Tralli s ones s shear s modulus of the undamaged matrix s undamaged matrix Poisson s ratio kl bulk s

Get Price### Blocked Shape Memory Eﬀect in Negative Poisson s Ratio

Negative Poisson s ratio foams may also show superior qualities when used in protection equipment because their material tends to ﬂow toward the impact zone (i.e. it becomes denser). Porous ﬁlters may also beneﬁt from the introduction of a negative Poisson s ratio since the area of the pores in auxetic materials opposite

Get Price### Rigorous connection between physical properties of porous

son s ratio to have a positive value this coefficient is positive for most geological materials and we will as- sume in this paper that (a) As a remark we emphasize that (2) is assumed for the Poisson s ratio of the solid constituent/grain of the porous material. Although the effective Poisson s ratio P-wave velocity of 6 000 m/s the P-wave half-wavelength is 1 800 m and the S-wave half-wavelength is 1 000 m for a Poisson s ratio v = 0.25. Consequently a good choice for the grid spacing is around 100 m. t is chosen to give a causal signal which is approximately zero for negative time

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of porous/microcracked metals Igor Sevostianov THEORETICAL AND APPLIED MECHANICS vol. 28-29 pp. Belgrade 2002 to pore aspect ratios and Poisson s ratio of the material. For a solid with many pores (analyzed in the framework of the Design of a porous material with isotropic negative Poisson s ratio Giorgio Carta a Michele Bruna Antonio Baldi aDipartimento di Ingegneria Meccanica Chimica e dei Materiali Universit a di Cagliari Piazza d Armi 09123 Cagliari Italy Abstract This paper proposes the design of a two-dimensional porous solid with omni-

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Poisson s Ratio of Porous and Microcracked Solids Theory and Application to Oxide Superconductors " J. Mater. Res. 10 (11) pp. Critical Reevaluation of the Prediction of Effective Poisson s Ratio for Porous Materials " J. Mater. Sci. 40 (21) pp. In material science and solid mechanics orthotropic materials have material properties at a particular point which differ along three mutually-orthogonal axes where each axis has twofold rotational symmetry.These directional differences in strength can be quantified with Hankinson s equation.. They are a subset of anisotropic materials because their properties change when measured from

Get Price### (PDF) A New Assessment Method for the Bulk Modulus and the

A key result of this study is that the effective Poisson s ratio depends only on pore concentration pore shape and Poisson s ratio of the bulk solid. In other words it is independent of any Microcracking-elasticity theories typically relate a decrement in elastic moduli to the number density N and the mean microcrack radius 〈a〉. In this paper four microcracking-modulus theories are rewritten in terms of the macroscopic observable parameters of Young s modulus and Poisson s ratio eliminating the specific dependence on the difficult to measure microscopic quantitiesN and

Get Price### Poisson s ratios of crystalline rocks as a function of

1. Introduction 2 Poisson s ratio (υ) named after a French mathematician Simeon Poisson who first analyzed it in 1829 is the negative of the ratio of transverse strain to the axial strain when an isotropic material is subjected to uniaxial stress only Gercek 2007 .For an isotropic material at a given temperature and a given pressure υ is a constant which lies between −1 and 0.5. Ledbetter H. and Lei M. (1991) Poisson s Ratio of Porous and Microcracked Solids Bandaj ile Sarılmış yara İltihaplanmış Yara Şişer Yara İyileşir Theory and Application to Oxide Superconductors Journal of Materials Research 6 2253–2255.

Get Price### Rigorous connection between physical properties of porous

son s ratio to have a positive value this coefficient is positive for most geological materials and we will as- sume in this paper that (a) As a remark we emphasize that (2) is assumed for the Poisson s ratio of the solid constituent/grain of the porous material. Although the effective Poisson s ratio A rigorous stable fixed-point is obtained for Poisson s ratio ν c of dry porous media where the location of this fixed-point depends only on the shape of the voids being added. Fixed-points occur at for spheres and ν c ≃πα/18 for cracks where α is the aspect ratio of penny-shaped cracks.

Get Price### A stress sensitivity model for the permeability of porous

A stress sensitivity model for the permeability of porous media based on bidispersed fractal theory is established considering the change of the flow path the fractal geometry approach and the mechanics of porous media. It is noted that the two fractal parameters of the porous media construction perform differently when the stress changes. son s ratio to have a positive value this coefficient is positive for most geological materials and we will as- sume in this paper that (a) As a remark we emphasize that (2) is assumed for the Poisson s ratio of the solid constituent/grain of the porous material. Although the effective Poisson s ratio

Get Price### Porosity-dependence of Effective Mechanical Properties of

New models for the elastic properties (Young s and shear moduli bulk modulus and Poisson s ratio) of two-phase pore-solid composites are developed using the differential effective medium approach Porosity-dependence of Effective Mechanical Properties of Pore-solid Composite Materials Employing the proposed quasi-static method Young s modulus Poisson s ratio and loss factor are measured for a poroelastic foam. The measured elastic properties are used in the Biot poroelasticity theory to predict the sound absorption coefficient of the foam. The prediction is finally compared with a standing wave tube measurement.

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