Constitutive relations for the shear band evolution in granular matter under large strain
Constitutive relations for the shear band evolution in granular matter under large strain
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DOI：
10.1016/j.partic.2008.07.020
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发表时间：
2008-12-01
期刊：
影响因子：
3.5
通讯作者：
Luding, Stefan
中科院分区：
文献类型：
--
作者：
Luding, Stefan
在缓慢的准静态变形下，所谓的“裂底环剪切胞”导致了较宽的剪切带。与普通的圆柱形Couette剪切计或流变仪不同，底板是分开的，这样它的外部部分可以与外壁一起移动，而另一部分(内盘)是固定的。从离散元模拟(DEM)出发，计算和评估了密度、速度、变形梯度和应力等多个连续体场，目的是为粉末流动行为建立客观的本构关系。在单次模拟前，通过时间和(局部)空间平均，得到了具有特殊应力相关性的非线性屈服面，各向异性总是小于宏观摩擦系数。然而，各向异性的下限随着应变率的增加而增加，并根据拉伸指数接近最大值，其特定的应变率与大约一个颗粒直径的剪切路径相一致。(C)2008年中国科学院颗粒学会和过程工程研究所。爱思唯尔出版，版权所有。
A so-called "split-bottom ring shear cell" leads to wide shear bands under slow, quasi-static deformation. Unlike normal cylindrical Couette shear cells or rheometers, the bottom plate is split such that the outer part of it can move with the outer wall, while, the other part (inner disk) is immobile. From discrete element simulations (DEM), several continuum fields like the density, velocity, deformation gradient and stress are computed and evaluated with the goal to formulate objective constitutive relations for the powder flow behavior. Front a single simulation, by applying time- and (local) space-averaging, a non-linear yield surface is obtained with peculiar stress dependence.The anisotropy is always smaller than the macroscopic friction coefficient. However, the lower bound of anisotropy increases with the strain rate, approaching the maximum according to a stretched exponential with a specific rate that is consistent with a shear path of about one particle diameter. (c) 2008 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.