Three-dimensional Modeling of Percolation Behavior of Electrical Conductivity in Segregated Network Polymer Nanocomposites Using Monte Carlo Method

Gu, Heng

doi:10.11648/j.am.20160501.11

Cited by 23 publications

(14 citation statements)

References 25 publications

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“…The experimental finding that a finite sample density is required for sample stability, i.e compression modulus E c > 0 (figure 9), allows us to make a connection to percolation theory [Gu et al, 2016]. (Eqn.…”

Section: Fibre Network and Percolation Theorymentioning

confidence: 99%

“…From figure 10a we then obtain that the value of the critical volume fraction φ v,c (φ i ) = ρ c (φ i )/ρ f varies linearly between 0.002 and 0.005. Gu et al [Gu et al, 2016] performed computer simulations of fibre networks. For a fibre aspect ratio of approxamity 57, as for the fibres in our experiments they report a critical volume fraction φ v,c of about 0.005, consistent with our data.…”

Section: Fibre Network and Percolation Theorymentioning

confidence: 99%

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Properties of lightweight fibrous structures made by a novel foam forming technique

et al. 2019

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We describe a novel method for the production of lightweight fibrous structures of densities as low as 8.8 kg.m −3. The method is based on the use of liquid foam as a carrier medium for dispersed Kraft fibres. Different to the process of foam forming, where the quick removal of the foam results in the formation of thin fibrous sheets, our samples are allowed to slowly drain and dry until all foam has disappeared. This procedure results in bulk samples whose height (up to 25 mm) and density are controlled by initial fibre concentration and liquid fraction of the foam. Above a minimum density, the compression modulus of elasticity of the samples increases linearly with density. Furthermore, we show compressive strength of the structures being controlled via the initial liquid fraction of the foam, making this an important process parameter for the fabrication of such structures.

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Section: Fibre Network and Percolation Theorymentioning

confidence: 99%

Section: Fibre Network and Percolation Theorymentioning

confidence: 99%

Properties of lightweight fibrous structures made by a novel foam forming technique

et al. 2019

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“…The integration of separated clusters happen when the concentration of nanotubes approaches a certain critical value. As a result in the system spreading (infinite) cluster is formed, which leads to appearance of the electric contacts between external electrodes in such a compound [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Experimental studies [1] have shown that the conductivity in nanotube polymeric and ceramic matrix materials follows a percolation-like behavior.…”

Section: Introductionmentioning

confidence: 99%

The Optimization at Studying of Electrical Conductivity in the Dielectric Nanocomposites With Disordered Nanotubes

Burlak¹,

Medina-Ángel²

2018

PIER Letters

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Abstract-We study the electrical conductivity of a three-dimensional (3D) nanocomposite with incorporated random carbon nanotubes (CNT). A large length of the remote nanotubes generates a lot of intersections that induce a rather small percolating threshold of the global conductivity in this medium. We simulate such a system by random cylinders placed in a percolating parallelepiped with the use of Monte Carlo method. The conductivity of such a structure is associated with the critical phenomena, where the main transition parameter is defined by the value of the percolation threshold. We calculate the minimal percolating threshold and determine the functional form of the conductivity by the global optimization technique. Such an approach allows studying the details of the electrical conductivity in nanocomposites even at significant level of the percolating fluctuations.

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“…Esse processo foi realizado por meio do arquivo .inp do ABAQUS. (3) Para determinar as coordenadas dos pontos de extremidade da -ésima fibra, é necessário definir com antecedência as coordenadas do seu ponto médio e os ângulos de orientação e , como realizado por Gu et al (2016). ( 1 , 1 , 1 ) e ( 2 , 2 , 2 ) são as coordenadas das extremidades 1 e 2 da -ésima fibra, respectivamente.…”

Section: Geração Das Fibrasunclassified

Estudo numérico e experimental da distribuição das fibras de aço em vigas de UHPFRC

Oliveira¹

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O concreto de ultra-alto desempenho (UHPC, sigla em inglês) é um material que apresenta alta resistência à compressão e durabilidade. Quando reforçado com fibras de aço (UHPFRC, sigla em inglês), passa a exibir um comportamento dúctil, alta resistência à tração e à flexão. A distribuição das fibras influencia significativamente o comportamento mecânico e estrutural desse material, sendo fundamental considerá-la nos estudos experimentais e numéricos.Entretanto, experimentalmente, há poucas investigações sobre a distribuição das fibras em elementos estruturais de UHPFRC, e, numericamente, a maioria dos modelos consideram-no homogêneo, o que impossibilita representar adequadamente tal distribuição. Nesse sentido, esta pesquisa objetiva investigar experimentalmente a influência das fibras e propor um modelo numérico em elementos finitos para o UHPFRC com fibras discretizadas e embutidas na matriz. Na etapa experimental, foram realizados ensaios de caracterização do UHPC e UHPFRC (1% e 2% de fibras) e de flexão em cinco vigas produzidas a partir desses concretos, cujos resultados confirmaram melhor desempenho ao UHPFRC (tanto no âmbito material quanto no estrutural).Além disso, foi realizada a análise de imagem por fotografia de alta resolução nas vigas de UHPFRC, que revelaram uma orientação preferencial das fibras. Numericamente, para possibilitar a representação da distribuição das fibras, visando a um menor custo computacional, elas foram discretizadas como elementos de treliça embutidos nos elementos que modelam a matriz (aderência perfeita). Assim, o deslizamento relativo da interface fibra/matriz foi representado no modelo constitutivo das fibras, por meio de uma lei tensão-deformação equivalente baseada no comportamento de arrancamento da fibra. A validação dessa estratégia numérica foi realizada modelando e simulando no ABAQUS os ensaios de caracterização (tração uniaxial e flexão a três pontos) e de flexão das vigas realizados experimentalmente. De modo geral, os resultados numéricos indicaram uma boa correlação com os resultados experimentais. Contudo, algumas sugestões foram propostas a fim de aprimorar o modelo numérico proposto. Palavras-chave: UHPFRC. Fibras. Vigas. Análise de imagem. Método dos elementos finitos. Elementos discretos embutidos.Ultra-high performance concrete (UHPC) is a material with high compressive strength and durability. When reinforced with steel fibers (UHPFRC) it becomes to exhibit a ductile behaviour and high tensile and flexural strength. Distribution of fibers significatively influences mechanical and structural behaviour of this material, and hence it has to be considered both in experimental and numerical studies. However, there are few experimental investigations on the fibers distribution in UHPFRC structural elements and, additionally, most of the numerical models consider this material as homogeneous, which makes it impossible to adequately represent such distribution. In this context, this research aims to experimentally investigate the influence of fibers distribution ...

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Three-dimensional Modeling of Percolation Behavior of Electrical Conductivity in Segregated Network Polymer Nanocomposites Using Monte Carlo Method

Cited by 23 publications

References 25 publications

Properties of lightweight fibrous structures made by a novel foam forming technique

Properties of lightweight fibrous structures made by a novel foam forming technique

The Optimization at Studying of Electrical Conductivity in the Dielectric Nanocomposites With Disordered Nanotubes

Estudo numérico e experimental da distribuição das fibras de aço em vigas de UHPFRC

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