Yielding and Flow of Soft-Jammed Systems in Elongation.
Yielding and Flow of Soft-Jammed Systems in Elongation.
复制标题
软堵塞系统在伸长过程中的屈服和流动。
DOI：
--
复制
发表时间：
2018
影响因子：
8.6
通讯作者：
Philippe Coussot
中科院分区：
文献类型：
--
作者：
X. Zhang;Omar Abdoulaye Fadoul;Elise Lorenceau;Philippe Coussot
到目前为止，软堵塞系统的屈服和流动特性仅从简单剪切开始研究，然后外推到其他流动情况。特别是，简单的流动，如拉伸几乎没有实验研究，或仅在一个非恒定的，部分体积的材料。我们表明，使用光滑的工具表面使得有可能获得一个长期的拉伸流在一个大范围的纵横比在整个体积的材料。具有不同微观结构的各种软堵塞系统测量的法向力表明，伸长屈服应力与剪切屈服应力的比率大于（约1.5倍）从标准理论，该理论假设应力张量是应变率张量的第二不变量的函数。这表明，材料的本构张量不能单独从宏观剪切测量确定。
So far, yielding and flow properties of soft-jammed systems have only been studied from simple shear and then extrapolated to other flow situations. In particular, simple flows such as elongations have barely been investigated experimentally or only in a nonconstant, partial volume of material. We show that using smooth tool surfaces makes it possible to obtain a prolonged elongational flow over a large range of aspect ratios in the whole volume of material. The normal force measured for various soft-jammed systems with different microstructures shows that the ratio of the elongation yield stress to the shear yield stress is larger (by a factor of around 1.5) than expected from the standard theory which assumes that the stress tensor is a function of the second invariant of the strain rate tensor. This suggests that the constitutive tensor of the materials cannot be determined solely from macroscopic shear measurements.