Vinutha H A, Diaz Ruiz Fabiola Doraly, Mao Xiaoming, Chakraborty Bulbul, Del Gado Emanuela
Department of Physics, Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington, DC 20057, USA.
Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA.
J Chem Phys. 2023 Mar 21;158(11):114104. doi: 10.1063/5.0131473.
We investigate the spatial correlations of microscopic stresses in soft particulate gels using 2D and 3D numerical simulations. We use a recently developed theoretical framework predicting the analytical form of stress-stress correlations in amorphous assemblies of athermal grains that acquire rigidity under an external load. These correlations exhibit a pinch-point singularity in Fourier space. This leads to long-range correlations and strong anisotropy in real space, which are at the origin of force-chains in granular solids. Our analysis of the model particulate gels at low particle volume fractions demonstrates that stress-stress correlations in these soft materials have characteristics very similar to those in granular solids and can be used to identify force chains. We show that the stress-stress correlations can distinguish floppy from rigid gel networks and that the intensity patterns reflect changes in shear moduli and network topology, due to the emergence of rigid structures during solidification.
我们使用二维和三维数值模拟研究了软颗粒凝胶中微观应力的空间相关性。我们采用了最近开发的一个理论框架，该框架预测了无热颗粒非晶态组件中应力-应力相关性的解析形式，这些颗粒在外部载荷下会获得刚性。这些相关性在傅里叶空间中表现出一个 pinch-point 奇点。这导致了实空间中的长程相关性和强各向异性，而这正是颗粒固体中力链的起源。我们对低颗粒体积分数下的模型颗粒凝胶进行的分析表明，这些软材料中的应力-应力相关性具有与颗粒固体中非常相似的特征，并且可用于识别力链。我们表明，应力-应力相关性可以区分松软凝胶网络和刚性凝胶网络，并且强度模式反映了剪切模量和网络拓扑结构的变化，这是由于固化过程中刚性结构的出现所致。
