软界面处的瞬态流体去除：圆柱-平面接触中接触时间控制的挤出效应
Transient fluid removal at soft interfaces: Contact-time-controlled squeeze-out in a cylinder-on-flat contact
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中文总结 AI 辅助
该研究通过圆柱-平面接触实验，揭示了软界面瞬态流体去除由总接触时间主导，低速滑动下挤出过程与稳态接触一致，滑动诱导的弹性流体动力效应影响极小。
中文摘要 AI 辅助
我们研究了刚性PMMA圆柱与软PDMS基底之间圆柱-平面接触中的瞬态流体去除现象。圆柱几何结构消除了可变形橡胶块可能出现的边缘刮擦机制，使得能够更直接地研究滑动对流体挤出的影响。实验主要在甘油中进行，滑动速度v=3 μm/s，使用不同表面粗糙度的圆柱。在初始弹性加载阶段后，我们发现滑动过程中的摩擦力主要取决于法向载荷施加后的总时间，而非先前的滑动距离。随后的摩擦力演化对总接触时间的依赖关系大致相同。稳态挤出计算预测了平均表面间距和真实接触面积的演化，与从测得摩擦力推断出的结果合理吻合。这些结果表明，稳态接触和低速滑动期间的流体去除本质上受相同的挤出过程控制，且在这些条件下，滑动诱导的弹性流体动力效应仅产生微小影响。
英文摘要
We study transient fluid removal in cylinder-on-flat contacts between stiff PMMA cylinders and a soft PDMS substrate. The cylinder geometry eliminates the edge-scraping mechanism that can occur for deformable rubber blocks, allowing the influence of sliding on fluid squeeze-out to be examined more directly. Experiments were performed mainly in glycerol at the low sliding speed $v=3 \ {\rm μm/s}$ using cylinders with different surface roughness. After the initial elastic-loading stage, we find that the friction during sliding depends primarily on the total time elapsed since application of the normal load rather than on the preceding sliding distance. The subsequent friction evolution follows approximately the same dependence on total contact time. Stationary squeeze-out calculations predict the evolution of the mean surface separation and real contact area, in reasonable agreement with that inferred from the measured friction. These results show that essentially the same squeeze-out process governs fluid removal during stationary contact and low-speed sliding, and that sliding-induced elastohydrodynamic effects have only a minor influence under these conditions.
