Yield stress and thixotropy: on the difficulty of measuring yield stresses in practice
Yield stress and thixotropy: on the difficulty of measuring yield stresses in practice
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DOI：
10.1039/b517840a
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发表时间：
2006-04-07
期刊：
影响因子：
3.4
通讯作者：
Bonn, D
中科院分区：
文献类型：
--
作者：
Moller, PCF;Mewis, J;Bonn, D
许多屈服应力流体的屈服应力已证明难以通过实验确定。这导致了文献中关于这些实验困难的各种讨论，以及屈服应力流体概念的有用性和相关性。在这里，我们认为，大多数的困难消失时，考虑到屈服应力流体的触变性，并将展示一个实验协议，允许获得可重复的数据，这些流体的流动所需的临界应力。作为奖励，我们将表明，屈服应力和触变性的相互作用，允许一个占无处不在的剪切局部化观察到这些材料。然而，由于触变性，屈服应力不再是材料特性，因为它取决于样品的（剪切）历史。
The yield stress of many yield stress fluids has turned out to be difficult to determine experimentally. This has led to various discussions in the literature about those experimental difficulties, and the usefulness and pertinence of the concept of yield stress fluids. We argue here that most of the difficulties disappear when taking the thixotropy of yield stress fluids into account, and will demonstrate an experimental protocol that allows reproducible data to be obtained for the critical stress necessary for flow of these fluids. As a bonus, we will show that the interplay of yield stress and thixotropy allows one to account for the ubiquitous shear localization observed in these materials. However, due to the thixotropy the yield stress is no longer a material property, since it depends on the (shear) history of the sample.