论文标题
薄水凝胶膜的瞬态滑动：毛弹性的作用
Transient sliding of thin hydrogel films: the role of poroelasticity
论文作者
论文摘要
我们报告了刚性球形玻璃探头和千分米厚的聚（二甲基丙烯酰胺）水凝胶膜之间接触的瞬时摩擦响应，当时将侧向相对运动最初在静止时施加到接触时，被移植到玻璃基板上。从\ textit {int intu}触点可视化的专用实验中，观察到摩擦力和接触大小的变化远远超出了在接触接口处的全面滑动条件的发生。根据施加的速度和启动运动前的静态接触时间，观察到摩擦力中的过冲或不强调。考虑到瞬态主要是由压力水凝胶网络中的水流驱动的，这些观察结果是合理化的。从使用薄膜近似的毛弹性接触模型的开发，我们提供了瞬态主要特征的理论描述。我们特别证明实验性观察是合理的，即摩擦力$ f_t（t）$对稳态的放松是由触点半径$ a（t）$的时间依赖性独立于滑动速度和施加的正常负载的独特性决定的。
We report on the transient frictional response of contacts between a rigid spherical glass probe and a micrometer-thick poly(dimethylacrylamide) hydrogel film grafted onto a glass substrate when a lateral relative motion is applied to the contact initially at rest. From dedicated experiments with \textit{in situ} contact visualization, both the friction force and the contact size are observed to vary well beyond the occurrence of a full sliding condition at the contact interface. Depending on the imposed velocity and on the static contact time before the motion is initiated, either an overshoot or an undershoot in the friction force is observed. These observations are rationalized by considering that the transient is predominantly driven by the flow of water within the stressed hydrogel networks. From the development of a poroelastic contact model using a thin film approximation, we provide a theoretical description of the main features of the transient. We especially justify the experimental observation that the relaxation of friction force $F_t(t)$ toward steady state is uniquely dictated by the time-dependence of the contact radius $a(t)$, independently on the sliding velocity and on the applied normal load.
