[1Ca02-12] SS1

[1Ca12S] How do viscoelastic objects begin to slide? -relation between precursor slip and friction coefficient-

*Wataru Iwashita¹, Hiroshi Matsukawa², Michio Otsuki¹ (1. Graduate School of Engineering Science, Osaka University, 2. College of Science and Engineering, Aoyama Gakuin University)

Recent studies have revealed that Amontons’ law of friction systematically breaks down for viscoelastic objects due to precursor slips occurring before the onset of bulk sliding in 2D system. However, it is not clear whether this result is applicable to more realistic 3D systems. In this study, we numerically investigate the slip motion of a 3D viscoelastic object on a solid substrate using a finite element method to resolve the problem mentioned above. The result indicates that the behavior of precursor slips and the macroscopic static friction coefficient depends on the pressure and the size of the object. Our theoretical analysis of a 1D effective model clarifies that the bulk sliding results from the instability associated with the competition between a velocity-weakening local friction and the bulk viscosity. The instability explains the dependence of the macroscopic static friction coefficient on the pressure and the size of the object.