The consolidation of suspended particulate matter under external forces such as pressure or gravity is of widespread interest. In this work, we derive a constitutive relation to describe the deformation of a {\it two-dimensional} strongly aggregated colloidal system by incorporating the inter-particle colloidal forces and contact dynamics. The theory accounts for the plastic events that occur in the form of rolling/sliding during the deformation along with elastic deformation. The theory predicts a yield stress that is a function of area fraction of the colloidal packing, the coordination number, the inter-particle potential, coefficient of friction and the normal and tangential stiffness coefficients. The predicted yield stress scales linearly with area fraction for low area fractions, and diverges at random close packing. Increasing the normal stiffness coefficient or the friction coefficient increases the yield stress. For stresses greater than the yield stress, both elastic and plastic deformations contribute to the overall stress.
ArGSLab: A tool for analyzing experimental or simulated particle networks
显微镜和基于颗粒的模拟都是研究聚集颗粒物质（如胶体凝胶）的强大技术。这些技术提供的数据通常包含大量长度尺度的信息，但结构分析方法通常侧重于局部颗粒排列，即使数据也包含有关介观长度尺度上颗粒网络的信息。在本文中，我们提出了一个MATLAB软件包，用于量化胶体样品中的介观网络结构。ArGSLab（Arrested and Gelated Structures Laboratory）从输入数据中提取网络骨干，然后将其转换为一组节点和链接，以进行基于图论的分析。该例程可以处理来自显微镜的图像堆栈以及显式坐标数据，从而允许模拟和实验之间的定量比较。此外，ArGSLab还可以精确分析显微镜数据，例如，扩展的点扩散函数禁止对单个粒子的分辨。我们展示了所得的输出，例如来自显微镜和胶体凝胶模拟的数据集，以展示ArGSLab定量分析各种来源数据的能力。免费提供的软件包可以使用提供的图形用户界面或直接作为MATLAB脚本。
