How do fire ants control the rheology of their aggregations? A statistical mechanics approach
How do fire ants control the rheology of their aggregations? A statistical mechanics approach
复制标题
火蚁如何控制其聚集体的流变性？
DOI：
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发表时间：
2018
影响因子：
3.9
通讯作者：
Robert J. Wagner
中科院分区：
文献类型：
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作者：
F. Vernerey;Tong Shen;S. L. Sridhar;Robert J. Wagner
主动网络在自然界中无所不在，从分子到宏观尺度。在这项研究中，我们探索了火蚁聚集体的机械行为，紧密结合的群体显示出令人印象深刻的动态，最终聚集体的自愈能力和适应环境的能力。虽然蚂蚁聚集体的弹性和流变性可以用现象学的力学模型（例如线性麦克斯韦或开尔文-沃伊特模型）来表征，但尚不清楚个体蚂蚁的行为如何影响聚集体的新兴反应。在这里，我们探索了另一种思考这些材料的方式，将它们描述为通过弹性链连接的个体的集合，这些链随着时间的推移而关联和分离。利用我们的知识，这些连接，例如，他们的弹性和附着/解离率，我们构建了一个统计描述的连接拉伸，并推导出相应的拉伸分布的演化方程。这种随时间变化的拉伸分布，然后用于确定重要的宏观措施，如应力，能量存储和能量耗散，在网络中。在这种情况下，我们展示了如何的物理特性和活动的个体蚂蚁可以解释的弹性，流动和剪切稀化的聚集。特别是，我们发现，实验结果相匹配，如果两个人之间的分离率增加与紧张的连接。
Active networks are omnipresent in nature, from the molecular to the macro-scale. In this study, we explore the mechanical behaviour of fire ant aggregations, closely knit swarms that display impressive dynamics culminating with the aggregations’ capacity to self-heal and adapt to the environment. Although the combined elasticity and rheology of the ant aggregation can be characterized by phenomenological mechanical models (e.g. linear Maxwell or Kelvin–Voigt model), it is not clear how the behaviour of individual ants affects the aggregations’ emerging responses. Here, we explore an alternative way to think about these materials, describing them as a collection of individuals connected via elastic chains that associate and dissociate over time. Using our knowledge of these connections—e.g. their elasticity and attachment/dissociation rates—we construct a statistical description of connection stretch and derive an evolution equation for the corresponding stretch distribution. This time-evolving stretch distribution is then used to determine important macroscopic measures, e.g. stress, energy storage and energy dissipation, in the network. In this context, we show how the physical characteristics and activities of individual ants can explain the elasticity, flow and shear thinning of the aggregation. In particular, we find that experimental results are matched if the detachment rate between two individuals increases with tension in the connection.