Prediction of the In-Plane Electrical Conductivity of a Misoriented Short Fiber Composite: Fiber Percolation Model Versus Effective Medium Theory

1987 ◽  
Vol 109 (3) ◽  
pp. 252-256 ◽  
Author(s):  
Minoru Taya ◽  
Naoki Ueda
Keyword(s):  
Electrical Conductivity ◽  
Volume Fraction ◽  
Effective Medium Theory ◽  
Fiber Composite ◽  
Short Fiber ◽  
Effective Medium ◽  
Percolation Model ◽  
Threshold Behavior ◽  
Medium Theory ◽  
Short Fiber Composite

The in-plane electrical conductivity of a misoriented short fiber composite was studied both by fiber percolation model (FPM) and effective medium theory (EMT). A misoriented short fiber composite consists of insulating matrix and conductive short fibers, thus it exhibits a threshold behavior in the conductivity at a certain volume fraction of fibers. A comparison between FPM and EMT indicates that FPM can predict the threshold behavior well, while EPT fails, but it becomes valid at high volume fraction of fibers.

TUNNELING PERCOLATION MODEL OF THE ELECTRICAL CONDUCTIVITY OF PARTICULATE NANOCOMPOSITES

2009 ◽  
Vol 23 (10) ◽  
pp. 1273-1279 ◽  
Author(s):  
LIU-JUAN ZHU ◽  
WEN-ZHONG CAI ◽  
BO-QIN GU ◽  
SHAN-TUNG TU
Keyword(s):  
Experimental Data ◽  
Electrical Conductivity ◽  
Percolation Theory ◽  
Effective Medium Theory ◽  
Effective Medium ◽  
Percolation Model ◽  
Medium Theory ◽  
Property Correlation ◽  
Conduction Behavior ◽  
Particle Statistics

The nanocomposites consisting of conducting nanoparticles and insulating matrix are studied. A tunneling percolation model is developed for their peculiar conduction behavior based on the equivalent-particle concept. It provides a clear microstructure-property correlation by combining many-particle statistics, effective-medium theory, and classical percolation theory. Its availability is assessed by available experimental data.

scholarly journals A proof that multiple waves propagate in ensemble-averaged particulate materials

2019 ◽  
Vol 475 (2229) ◽  
pp. 20190344 ◽  
Author(s):  
Artur L. Gower ◽  
I. David Abrahams ◽  
William J. Parnell
Keyword(s):  
Acoustic Waves ◽  
Volume Fraction ◽  
Effective Medium Theory ◽  
Effective Medium ◽  
Inhomogeneous Material ◽  
Ensemble Averaging ◽  
Reflection And Transmission ◽  
Medium Theory ◽  
Transmission Coefficients ◽  
Cylindrical Inclusions

Effective medium theory aims to describe a complex inhomogeneous material in terms of a few important macroscopic parameters. To characterize wave propagation through an inhomogeneous material, the most crucial parameter is the effective wavenumber . For this reason, there are many published studies on how to calculate a single effective wavenumber. Here, we present a proof that there does not exist a unique effective wavenumber; instead, there are an infinite number of such (complex) wavenumbers. We show that in most parameter regimes only a small number of these effective wavenumbers make a significant contribution to the wave field. However, to accurately calculate the reflection and transmission coefficients, a large number of the (highly attenuating) effective waves is required. For clarity, we present results for scalar (acoustic) waves for a two-dimensional material filled (over a half-space) with randomly distributed circular cylindrical inclusions. We calculate the effective medium by ensemble averaging over all possible inhomogeneities. The proof is based on the application of the Wiener–Hopf technique and makes no assumption on the wavelength, particle boundary conditions/size or volume fraction. This technique provides a simple formula for the reflection coefficient, which can be explicitly evaluated for monopole scatterers. We compare results with an alternative numerical matching method.

Thermal Residual Stress in a Two-Dimensional In-Plane Misoriented Short Fiber Composite

1990 ◽  
Vol 43 (5S) ◽  
pp. S294-S303 ◽  
Author(s):  
M. Taya ◽  
M. Dunn ◽  
B. Derby ◽  
J. Walker
Keyword(s):  
Residual Stress ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Fiber Composite ◽  
Short Fiber ◽  
Two Dimensional ◽  
Fiber Distribution ◽  
Fiber Volume ◽  
Distribution Type ◽  
Short Fiber Composite

Residual stress induced in a misoriented short fiber composite due to thermal expansion mismatch between the matrix and fiber is investigated. The case of two-dimensional in-plane fiber misorientation is considered. The elastic model that is developed is based on Eshelby’s equivalent inclusion method and is unique in that it accounts for interactions among fibers at different orientations. A parametric study is performed to demonstrate the effects of fiber volume fraction, fiber aspect ratio, fiber distribution cut-off angle, and fiber distribution type on thermal residual stress. Fiber volume fraction and aspect ratio are shown to have more significant effects on the magnitude of the thermal residual stresses than the fiber distribution type and cut-off angle.

Interphase approach for modeling the DC conductivity of diverse allotropic types of carbon-reinforced polymer composites

2020 ◽  
pp. 073168442097326
Author(s):  
Y Nioua ◽  
N Aribou ◽  
S Boukheir ◽  
ME Achour ◽  
LC Costa
Keyword(s):  
Electrical Conductivity ◽  
Composite Materials ◽  
Polymer Composites ◽  
Volume Fraction ◽  
Effective Medium Theory ◽  
Effective Medium ◽  
Simple Extension ◽  
Modified Model ◽  
Dc Electrical Conductivity ◽  
Reinforced Polymer

This work is based on a generalized effective medium-modified model for predicting the DC electrical conductivity of polymer composites, taken into account the interactions between the components using an interphase approach. Generalized effective medium-modified model is a simple extension of the Generalized Effective Medium Theory proposed by McLachlan. We studied the modeling of the DC electrical conductivity using the proposed model for diverse allotropic types of carbon-reinforced polymer composites. Three series of composite materials obtained by mixing an insulating matrix DGEBA with (i) carbon nanotubes which are one-dimensional materials (1 D), (ii) reduced graphene oxide, which is a two-dimensional material (2 D) and (iii) carbon black, which is a three-dimensional material (3 D) have been studied. Predictions from the model are in good agreement with the experimental data of the electrical conductivity of composite materials, where the classical models have not been able to explain them. Moreover, in this paper, the effects of the filler dimension on the interphase properties of the composite materials, in particular the interphase volume fraction and the interphase conductivity, have been investigated.

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