From well-controlled long creep tests, we show that the residual apparent yield stress observed with soft-jammed systems along smooth surfaces is an artifact due to edge effects. By removing these effects, we can determine the stress solely associated with steady-state wall slip below the material yield stress. This stress is found to vary linearly with the slip velocity for a wide range of materials whatever the structure, the interaction types between the elements and with the wall, and the concentration. Thus, wall slip results from the laminar flow of some given free liquid volume remaining between the (rough) jammed structure formed by the elements and the smooth wall. This phenomenon may be described by the simple shear flow in a Newtonian liquid layer of uniform thickness. For various systems, this equivalent thickness varies in a narrow range ($35\pm 15\mathrm{nm}$).

中文翻译：

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软夹套系统的壁滑：通用的简单剪切过程

从控制良好的长蠕变测试中，我们表明，沿边缘光滑的系统在软干扰系统中观察到的残余表观屈服应力是由边缘效应引起的伪影。通过消除这些影响，我们可以确定仅与材料屈服应力以下的稳态壁滑相关的应力。对于各种材料，无论结构，元件之间以及与壁之间的相互作用类型以及浓度如何，都发现该应力随滑移速度线性变化。因此，壁滑是由残留在由元件形成的（粗糙）被卡住的结构和光滑壁之间的一些给定的自由液体的层流引起的。这种现象可以用均匀厚度的牛顿液体层中的简单剪切流来描述。对于各种系统，$35\pm 15\mathrm{纳米}$）。