Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA.
Phys Rev Lett. 2018 Jun 1;120(22):224101. doi: 10.1103/PhysRevLett.120.224101.
We measure the static frictional resistance and the real area of contact between two solid blocks subjected to a normal load. We show that following a two-step change in the normal load the system exhibits nonmonotonic aging and memory effects, two hallmarks of glassy dynamics. These dynamics are strongly influenced by the discrete geometry of the frictional interface, characterized by the attachment and detachment of unique microcontacts. The results are in good agreement with a theoretical model we propose that incorporates this geometry into the framework recently used to describe Kovacs-like relaxation in glasses as well as thermal disordered systems. These results indicate that a frictional interface is a glassy system and strengthen the notion that nonmonotonic relaxation behavior is generic in such systems.
我们测量了两个在法向载荷作用下的固体块之间的静摩擦力和实际接触面积。我们表明，在法向载荷经历了两步变化后，系统表现出非单调老化和记忆效应，这是玻璃动力学的两个标志。这些动力学受到摩擦界面离散几何的强烈影响，其特征是独特微接触的附着和脱离。这些结果与我们提出的理论模型非常吻合，该模型将这种几何形状纳入了最近用于描述玻璃以及热无序系统中类似科瓦克斯的弛豫的框架中。这些结果表明，摩擦界面是一个玻璃态系统，并加强了这样的系统中存在非单调弛豫行为的观点。
