Kinetics of the coefficient of friction of elastomers

Abstract

We study theoretically and numerically the kinetics of the coefficient of friction of an elastomer due to abrupt changes of sliding velocity. Numerical simulations reveal the same qualitative behavior which has been observed experimentally on different classes of materials: the coefficient of friction first jumps and then relaxes to a new stationary value. The elastomer is modeled as a simple Kelvin body and the surface as a self-affine fractal with a Hurst exponent in the range from 0 to 1. Parameters of the jump of the coefficient of friction and the relaxation time are determined as functions of material and loading parameters. Depending on velocity and the Hurst exponent, relaxation of friction with characteristic length or characteristic time is observed.

Atomically precise, custom-design origami graphene nanostructures

“…For example, by comparing their spectra, we find that there exists a small energy shift (31 meV) of the VHS gap from the Fermi energy for the tubular edge in Fig. 3A, which can be attributed to interactions between the tubular edge and the substrate because the (10,8) tube should behave more as a semiconductor while the (12, 3) tube is more metallic (39,40). These observations highlight the opportunity to investigate effects of the local environment on low-dimensional electronic properties by using the STM origami.…”

“…3B is 19 ± 1°. Correspondingly, these two single-walled tubes are (10,8) and (12,3), respectively (see more detailed analysis in fig. S5).…”

“…The discovery of fullerenes, nanotubes, and, more recently, the isolation of monolayer graphene sparked a revolution in the fabrication of an extraordinary variety of sp 2 -bonded carbon allotropes (1, 2). Graphene itself, along with variants that include five-and/or seven-member rings, can be viewed as building blocks of sp 2 -bonded allotropes (3) and of three-dimensional graphene-based nanostructures (GNSs) and devices that have been either fabricated or predicted theoretically for potential applications (4-7), even machines (8).…”

Spatial correlations in driven-dissipative photonic lattices

“…It has been successfully applied to various lattice models such as the Bose-Hubbard and Jaynes-Cummings-Hubbard model [26][27][28][29][30][31] as well as related spin models [32][33][34]. Recent efforts to improve on the mean-field approximation include perturbative [35,36], projective [37], cluster [38], variational [39] and equations-ofmotion approaches [40].…”

On the role of scales in elastomer friction

“…Therefore any model that correctly describes the contact stiffness on the largest scale and reproduces the gradient of the surface profile on the smallest scale, is eligible for the study of frictional processes. Examples of models based on the two-scale nature of frictional contacts can be found in [22,23].…”