Ortiz Carlos P, Daniels Karen E, Riehn Robert
Department of Physics, North Carolina State University, Raleigh, North Carolina, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2014 Aug;90(2):022304. doi: 10.1103/PhysRevE.90.022304. Epub 2014 Aug 26.
Thermal fluctuations, geometric exclusion, and external driving all govern the mechanical response of dense particulate suspensions. Here, we measure the stress-strain response of quasi-two-dimensional flow-stabilized microsphere heaps in a regime in which all three effects are present using a microfluidic device. We observe that the elastic modulus and the mean interparticle separation of the heaps are tunable via the confining stress provided by the fluid flow. Furthermore, the measured stress-strain curves exhibit a universal nonlinear shape, which can be predicted from a thermal van der Waals equation of state with excluded volume. This analysis indicates that many-body interactions contribute a significant fraction of the stress supported by the heap.
热涨落、几何排斥和外部驱动都决定了稠密颗粒悬浮液的力学响应。在此，我们使用微流控装置，在所有这三种效应都存在的情况下，测量了准二维流动稳定的微球堆的应力 - 应变响应。我们观察到，堆的弹性模量和平均颗粒间间距可通过流体流动提供的围压进行调节。此外，测量得到的应力 - 应变曲线呈现出一种通用的非线性形状，这可以从具有排除体积的热范德瓦尔斯状态方程预测出来。该分析表明，多体相互作用在堆所承受的应力中占很大一部分。
