Department of Engineering Mechanics, SVL and MMML, Xi'an Jiaotong University, Xi'an, 710049, China.
Sci Rep. 2021 Oct 13;11(1):20366. doi: 10.1038/s41598-021-99909-2.
Classical laws of friction suggest that friction force is proportional to the normal load and independent of the nominal contact area. As a great improvement in this subject, it is now widely accepted that friction force is proportional to the real contact area, and much work has been conducted based on this hypothesis. In present study, this hypothesis will be carefully revisited by measuring the friction force and real contact area in-site and real-time at both normal loading and unloading stages. Our experiments reveal that the linear relation always holds between friction force and normal load. However, for the relation between friction force and real contact area, the linearity holds only at the loading stage while fails at the unloading stage. This study may improve our understanding of the origin of friction.
经典摩擦定律表明摩擦力与法向载荷成正比，与名义接触面积无关。作为这一领域的重大改进，现在人们普遍接受摩擦力与真实接触面积成正比，并且已经基于这一假设进行了大量工作。在本研究中，我们将通过在正常加载和卸载阶段实时原位测量摩擦力和真实接触面积，仔细重新审视这一假设。我们的实验表明，摩擦力与法向载荷之间始终保持线性关系。然而，对于摩擦力与真实接触面积之间的关系，线性关系仅在加载阶段成立，而在卸载阶段则不成立。这项研究可能有助于我们理解摩擦力的起源。
