在本文中，研究人员研究了几何形状对相对运动的软表面动态响应的影响。研究人员使用一个简单的实验方案，测量了高度可弯曲的薄聚合物片和水凝胶基板之间的摩擦。在这种柔软的低摩擦界面上，研究人员发现摩擦对两个表面的相对几何形状有很强的依赖性——一个平片在球形基底上比在平面或圆柱形基底上经历更大的摩擦。研究表明，由于其几何不相容的约束，在平片中产生的应力是摩擦增强的原因。
这种机制也会导致摩擦性质的转变，因为平片半径增加到超过临界值。这项研究发现揭示了迄今为止未被注意到的基于几何和弹性之间相互作用的机制，这可能会显著影响软、生物和纳米级系统中的摩擦。特别是，它促使研究人员重新审视他们对生物细胞移动的曲率依赖等现象的理解。
据悉，软物质和生物物质有各种各样的形状和几何形状。当由于高斯曲率不匹配而不能相互适应的软表面形成界面时，已知会出现美丽的几何诱导图案。
附：英文原文
Title: Geometry-induced friction at a soft interface
Author: Chawla, Aashna, Kumar, Deepak
Issue&Volume: 2024-7-18
Abstract: Soft and biological matter come in a variety of shapes and geometries. When soft surfaces that do not fit into each other due to a mismatch in Gaussian curvatures form an interface, beautiful geometry-induced patterns are known to emerge. In this paper, we study the effect of geometry on the dynamical response of soft surfaces moving relative to each other. Using a simple experimental scheme, we measure friction between a highly bendable thin polymer sheet and a hydrogel substrate. At this soft and low-friction interface, we find a strong dependence of friction on the relative geometry of the two surfaces—a flat sheet experiences significantly larger friction on a spherical substrate than on flat or cylindrical substrate. We show that the stress developed in the sheet due to its geometrically incompatible confinement is responsible for the enhanced friction. This mechanism also leads to a transition in the nature of friction as the sheet radius is increased beyond a critical value. Our finding reveals a hitherto unnoticed mechanism based on an interplay between geometry and elasticity that may influence friction significantly in soft, biological, and nanoscale systems. In particular, it provokes us to reexamine our understanding of phenomena such as the curvature dependence of biological cell mobility.
DOI: 10.1073/pnas.2320068121
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2320068121