[S-CG74] [JJ] Rheology, fracture and friction in Earth and planetary sciences

[SCG74-14] Asperity contact and constitutive relations in gel friction

*Tetsuo Yamaguchi¹ (1.Graduate school of Engineering, Kyushu University)

Keywords:frictional constitutive relation, stick-slip, slow slip, asperity, laboratory experiment

It is believed that asperity contact plays an important role in fricton, in particular in onset of dynamic slip or stick-slip motions. However, there remain very few studies controling asperities and observing their effects on mascoscopic stick-slip behavior or frictional constitutive laws. Here we perform stick-slip friction experiments between compliant gels with well-controlled asperity shape/size/configurations by molding technique. We find that, as curvature radius of the asperity becomes larger and the normal stress becomes smaller, velocity dependence turns from rate-strengthening to rate-weakening and accordingly, frictional behavior transitions from steady sliding, slow slip to fast slip. In this talk, we discuss the asperity size effects based on microscopic/macroscopic observations as well as a theoretical argument.