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Computational studies on the effective properties of two-phase heterogeneous media.

机译:关于两相异质介质有效特性的计算研究。

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摘要

The effective elastic modulus and conductivity of a two phase material system are investigated computationally using a Monte Carlo scheme. The continuum contains circular, spherical or ellipsoidal inclusions that are either uniformly or randomly embedded in the matrix. The computed results are compared to the applicable effective medium theories. It is found that the random distribution, permeability and particle aspect ratio have non-negligible effects on the effective material properties. For spherical inclusions, the effective medium approximations agree well with the simulation results in general, but the analytical predictions on void or non-spherical inclusions are much less reliable. It is found that the results for overlapping and nonoverlapping inclusions do not differ very much at the same volume fraction. The effect of the particle morphology is also investigated in the context of prolate and oblate ellipsoidal particles.;The geometric percolation thresholds for circular, elliptical, square and triangular disks in the three-dimensional space are determined precisely by Monte Carlo simulations. These geometries represent oblate particles in the limit of zero thickness. The normalized percolation points, which are estimated by extrapolating the data to zero radius, are etac=0.9614+/-0.0005, 0.8647+/-0.0006 and 0.7295+/-0.0006 for circles, squares and equilateral triangles, respectively. These results show that the noncircular shapes and corner angles in the disk geometry tend to increase the interparticle connectivity and therefore reduce the percolation point. For elliptical plate, the percolation threshold is found to decrease moderately when the aspect ratio epsilon is between 1 and 1.5 but decrease rapidly for epsilon greater than 1.5. For the binary dispersion of circular disks with two different radii, etac is consistently larger than that of equisized plates, with the maximum value located at around r1/r2 =0.5.
机译:使用蒙特卡洛方案以计算方式研究了两相材料系统的有效弹性模量和电导率。该连续体包含均匀地或随机地嵌入基质中的圆形,球形或椭圆形夹杂物。将计算结果与适用的有效介质理论进行比较。发现随机分布,渗透性和颗粒长径比对有效材料性能具有不可忽略的影响。对于球形夹杂物,有效的介质近似值通常与模拟结果吻合得很好,但是对空隙或非球形夹杂物的分析预测却不那么可靠。发现在相同的体积分数下,重叠和非重叠夹杂物的结果差异不大。还研究了扁长形和扁圆形的椭圆形粒子的粒子形态的影响。三维空间中圆形,椭圆形,正方形和三角形圆盘的几何渗透阈值是通过蒙特卡洛模拟精确确定的。这些几何形状代表零厚度范围内的扁圆形颗粒。通过将数据外推到零半径而估算出的归一化渗滤点,对于圆形,正方形和等边三角形,etac = 0.9614 +/- 0.0005、0.8647 +/- 0.0006和0.7295 +/- 0.0006。这些结果表明,圆盘几何形状中的非圆形形状和转角会增加颗粒间的连通性,从而降低渗滤点。对于椭圆板,当长径比ε在1和1.5之间时,渗滤阈值会适度降低,而对于大于1.5的ε,渗滤阈值会迅速降低。对于具有两个不同半径的圆盘的二元色散,etac始终大于等效板的二元色散,最大值位于r1 / r2 = 0.5左右。

著录项

  • 作者

    Tawerghi, Elyas E.;

  • 作者单位

    University of Denver.;

  • 授予单位 University of Denver.;
  • 学科 Engineering Mechanical.;Engineering Materials Science.
  • 学位 M.S.
  • 年度 2009
  • 页码 116 p.
  • 总页数 116
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;工程材料学;
  • 关键词

  • 入库时间 2022-08-17 11:37:38

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