Friction induced pattern formations and modal transitions in a mass-spring chain model of sliding interface

Friction induced modal transitions and pattern formations are investigated both analytically and numerically based on a mesoscopic mass-spring chain model of sliding interfaces. The case of smooth self-sustained oscillations is considered first based on a two-degrees-of-freedom model with a generalized Rayleigh's dissipative term by means of a new type of descriptive variables characterizing total excitation level, its distribution between the oscillators, and coherency of oscillations. In particular, it is shown that there exists a threshold of excitation above which self-sustained nonlinear normal and local oscillations are possible. The existence of threshold for generation of standing and propagating waves in the corresponding mass-spring chain is confirmed by both analytical estimates and numerical simulations. Also, it is shown that friction induced oscillations with a creeping phase develop according to a qualitatively different scenario leading to amplitude modulated waves with the highest possible carrying mode. (C) 2020 Elsevier Ltd. All rights reserved.