Novel Friction Law for the Static Friction Force based on Local Precursor Slipping

摘要

The sliding of a solid object on a solid substrate requires a shear forcethat is larger than the maximum static friction force. It is commonly believedthat the maximum static friction force is proportional to the loading force anddoes not depend on the apparent contact area. The ratio of the maximum staticfriction force to the loading force is called the static friction coefficientmM, which is considered to be a constant. Here, we conduct experimentsdemonstrating that the static friction force of a slider on a substrate followsa novel friction law under certain conditions. The magnitude of mM decreases asthe loading force increases or as the apparent contact area decreases. Thisbehavior is caused by the slip of local precursors before the onset of bulksliding and is consistent with recent theory. The results of this study willdevelop novel methods for static friction control.