Directed network topologies of smart grain sensors
Directed network topologies of smart grain sensors
复制标题
DOI：
10.1103/physreve.87.032203
复制
发表时间：
2013-03
影响因子：
2.4
通讯作者：
D. M. Walker;A. Tordesillas;Tomomichi Nakamura;T. Tanizawa
中科院分区：
文献类型：
--
作者：
D. M. Walker;A. Tordesillas;Tomomichi Nakamura;T. Tanizawa
我们采用了最近的技术，从时间序列数据构建复杂的网络，构建一个有向网络体现时间结构，整理在一系列双轴压缩试验中的预测性能的个别颗粒传感器。对于每个颗粒，我们重建一个静态预测模型。这结合了子集选择算法和信息理论拟合标准，该标准选择组件中的哪些其他晶粒最好放置以预测给定晶粒在整个加载历史中的局部应力。颗粒在每个时间步的局部应力由其颗粒载荷矢量的大小来概括。有向网络通过将每个颗粒表示为节点来构造，并且如果在第一颗粒的最佳预测模型内选择了另一颗粒，则将入链路分配给来自另一颗粒的颗粒。因此，出度大的晶粒对预测其他晶粒的应力历史最负责任：这些晶粒原来只是位于剪切带内的少数晶粒。此外，这些“智能颗粒”被证明是密切相关的机制，力链屈曲和间歇性响尾蛇事件。只有少量的粮食传感器位于剪切带中需要准确地捕捉流变学响应的所有其他谷物在大会强调非局部相互作用的至关重要性，支持扩展连续介质理论，其中包括非局部演化规律。这里的研究结果投下聚光灯在两个特定的机制，作为制定强大的演化规律在压缩和剪切变形颗粒状材料的关键：长期持有的机制，能量耗散的力链屈曲和突然切换的角色，摇铃扮演，因为它进入和退出力链。
We employ a recent technique for building complex networks from time series data to construct a directed network embodying time structure to collate the predictive properties of individual granular sensors in a series of biaxial compression tests. For each grain, we reconstruct a static predictive model. This combines a subset selection algorithm and an information theory fitting criterion that selects which other grains in the assembly are best placed to predict a given grain's local stress throughout loading history. The local stress of a grain at each time step is summarized by the magnitude of its particle load vector. A directed network is constructed by representing each grain as a node, and assigning an in-link to a grain from another grain if the latter is selected within the best predictive model of the first grain. The grains with atypically large out-degree are thus the most responsible for predicting the stress history of the other grains: These turn out to be only a few grains which reside inside shear bands. Moreover, these “smart grains” prove to be strongly linked to the mechanism of force chain buckling and intermittent rattler events. That only a small number of grain sensors situated in the shear band are required to accurately capture the rheological response of all other grains in the assembly underlines the crucial importance of nonlocal interactions, espoused by extended continuum theories which posit nonlocal evolution laws. Findings here cast the spotlight on two specific mechanisms as being key to the formulation of robust evolution laws in deforming granular materials under compression and shear: the long held mechanism for energy dissipation of force chain buckling and the sudden switch in roles that a rattler plays as it enters in and out of force chains.