Impedance/Dielectric Spectroscopy of Electroceramics?Part 2: Grain Shape Effects and Local Properties of Polycrystalline Ceramics

2005 ◽  
Vol 14 (3) ◽  
pp. 293-301 ◽  
Author(s):  
N. J. Kidner ◽  
Z. J. Homrighaus ◽  
B. J. Ingram ◽  
T. O. Mason ◽  
E. J. Garboczi
Keyword(s):  
Dielectric Spectroscopy ◽  
Grain Shape ◽  
Polycrystalline Ceramics ◽  
Shape Effects ◽  
Local Properties

Grain shape effects on dielectric and electrical properties of rocks

Geophysics ◽  
1984 ◽  
Vol 49 (5) ◽  
pp. 586-587 ◽  
Author(s):  
P. N. Sen
Keyword(s):  
Grain Shape ◽  
Angular Frequency ◽  
Dc Conductivity ◽  
Dielectric Constants ◽  
Water Conductivity ◽  
Depolarization Factor ◽  
The Matrix ◽  
Shape Effects ◽  
Dielectrical Properties ◽  
The Right

Recently there has been a considerable interest in the effect of anisotropy in the grain shape in the electrical and dielectrical properties of rocks and other inhomogeneous media (Sen 1981a, b; Sen et al, 1981; Mendelson and Cohen, 1982; and Kenyon, 1983). In this note I point out that equation (34) of Mendelson and Cohen (MC) is incorrect. The dc limit of MC equation (34) for the conductivity of rock σ, in terms of porosity ϕ and water conductivity [Formula: see text], gives [Formula: see text] or [Formula: see text] where [Formula: see text] L is the depolarization factor along the principal axis of spheroidal grain and 〈 〉 denotes an average over the distribution in L. This value of [Formula: see text] is in disagreement with the correct value of m in equation (28) of MC [equation (6) below]. [When the sign mistakes in equations MC (33)–(34) are corrected, [Formula: see text]. This agrees with equation (6) below for the case when L has a single value and averaging is redundant.] This inconsistency arises from an incorrect replacement of the inverse of an average in MC equation (33) by an average of inverses. The corrected form of MC equation (33) is [Formula: see text] where ε and [Formula: see text] are the dielectric constants of the mixture and of the matrix, respectively. The dielectric constant [Formula: see text] is complex, [Formula: see text] is real, [Formula: see text] is the permittivity of vacuum, σ the conductivity, ω the angular frequency. The last factor in the right‐hand side of the equation was replaced incorrectly by the average of the inverse, which is incorrect in general. Note that in the dc limit equation (4) above gives [Formula: see text] and, by integration, [Formula: see text] where [Formula: see text] is the dc conductivity of water, σ(0) is the dc conductivity of formation, and [Formula: see text]

Grain shape effects on the slip system activity and on the lattice rotations

1986 ◽  
Vol 34 (11) ◽  
pp. 2139-2149 ◽  
Author(s):  
S. Tiem ◽  
M. Berveiller ◽  
G.R. Canova
Keyword(s):  
Slip System ◽  
Grain Shape ◽  
System Activity ◽  
Shape Effects

Grain Shape Effects on Settling Rates

1978 ◽  
Vol 86 (2) ◽  
pp. 193-209 ◽  
Author(s):  
P. D. Komar ◽  
C. E. Reimers
Keyword(s):  
Grain Shape ◽  
Shape Effects ◽  
Settling Rates

Grain Shape Effects on Permeability, Formation Factor, and Capillary Pressure from Pore-Scale Modeling

2013 ◽  
Vol 102 (1) ◽  
pp. 71-90 ◽  
Author(s):  
T. Torskaya ◽  
V. Shabro ◽  
C. Torres-Verdín ◽  
R. Salazar-Tio ◽  
A. Revil
Keyword(s):  
Capillary Pressure ◽  
Grain Shape ◽  
Pore Scale ◽  
Formation Factor ◽  
Scale Modeling ◽  
Pore Scale Modeling ◽  
Shape Effects

Grain Shape Effects on Settling Rates: A Discussion

1980 ◽  
Vol 88 (2) ◽  
pp. 243-245 ◽  
Author(s):  
N. C. Janke
Keyword(s):  
Grain Shape ◽  
Shape Effects ◽  
Settling Rates

scholarly journals Numerical Investigation of Mineral Grain Shape Effects on Strength and Fracture Behaviors of Rock Material

2019 ◽  
Vol 9 (14) ◽  
pp. 2855 ◽  
Author(s):  
Zhenhua Han ◽  
Luqing Zhang ◽  
Jian Zhou
Keyword(s):  
Elastic Modulus ◽  
Quantitative Methods ◽  
Significant Positive Correlation ◽  
Grain Shape ◽  
Peak Strength ◽  
Particle Flow ◽  
Particle Flow Code ◽  
Mechanical Behaviors ◽  
Fracture Behaviors ◽  
Shape Effects

Rock is an aggregate of mineral grains, and the grain shape has an obvious influence on rock mechanical behaviors. Current research on grain shape mostly focuses on loose granular materials and lacks standardized quantitative methods. Based on the CLUMP method in the two-dimensional particle flow code (PFC2D), three different grain groups were generated: strip, triangle, and square. Flatness and roughness were adopted to describe the overall contour and the surface morphology of the mineral grains, respectively. Simulated results showed that the grain shape significantly affected rock porosity and further influenced the peak strength and elastic modulus. The peak strength and elastic modulus of the model with strip-shaped grains were the highest, followed by the models with triangular and square grains. The effects of flatness and roughness on rock peak strength were the opposite, and the peak strength had a significant, positive correlation with cohesion. Tensile cracking was dominant among the generated microcracks, and the percentage of tensile cracking was maximal in the model with square grains. At the postpeak stage, the interlocking between grains was enhanced along with the increased surface roughness, which led to a slower stress drop.

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