近日，以色列威茨曼科学研究所的Eran Bouchbinder及其研究小组与德国于利希研究中心的Efim A.Brener等人合作并取得一项新进展。经过不懈努力，他们揭示了非定常摩擦滑移脉冲的动力学。相关研究成果已于2023年8月17日在国际知名学术期刊《美国科学院院刊》上发表。

该研究团队在真实的速率和状态依赖的摩擦系统中发展了滑移脉冲理论。研究表明，滑移脉冲本质上是不稳定的对象，这与先前的发现一致，但它们的动态演化与它们的不稳定稳态对应体密切相关。特别地，研究人员证明了沿时间无关的L⁽⁰⁾(τ_d)-c_p⁽⁰⁾(τ_d)线的每个点都是不稳定的，这是由驱动剪切应力τ_d参数化的稳态脉冲解族得到的。然而，值得注意的是，c_p⁽⁰⁾[L⁽⁰⁾]线是一个动态吸引子，使得滑移脉冲的非定常动力学（当它们存在时）——无论是增长（L˙(t)>0）还是衰减（L˙(t)<0）——都驻留在稳态线上。沿线的非定常动力学由单一慢速不稳定模式控制。

增长脉冲的缓慢动力学表现为L˙(t)/c_p(t)<<1，解释了持续脉冲的存在，即脉冲可以传播许多倍于其特征尺寸而不会明显改变其性质。该研究的非定常摩擦滑移脉冲的理论图景得到了大规模动态边界积分方法模拟的定量支持。

据悉，自愈合滑移脉冲是摩擦系统的主要时空失效模式，其特征尺寸为L(t)，传播速度为c_p(t)（t为时间）。

附：英文原文

Title: The dynamics of unsteady frictional slip pulses

Author: Pomyalov, Anna, Barras, Fabian, Roch, Thibault, Brener, Efim A., Bouchbinder, Eran

Issue&Volume: 2023-8-17

Abstract: Self-healing slip pulses are major spatiotemporal failure modes of frictional systems, featuring a characteristic size L(t) and a propagation velocity c_p(t) (t is time). Here, we develop a theory of slip pulses in realistic rate- and state-dependent frictional systems. We show that slip pulses are intrinsically unsteady objects—in agreement with previous findings—yet their dynamical evolution is closely related to their unstable steady-state counterparts. In particular, we show that each point along the time-independent L⁽⁰⁾(τ_d)-c_p⁽⁰⁾(τ_d) line, obtained from a family of steady-state pulse solutions parameterized by the driving shear stress τ_d, is unstable.Nevertheless, and remarkably, the c_p⁽⁰⁾[L⁽⁰⁾] line is a dynamic attractor such that the unsteady dynamics of slip pulses (when they exist)—whether growing (L˙(t)>0) or decaying (L˙(t)<0)—reside on the steady-state line. The unsteady dynamics along the line are controlled by a single slow unstable mode. The slow dynamics of growing pulses, manifested by L˙(t)/c_p(t)<<1, explain the existence of sustained pulses, i.e., pulses that propagate many times their characteristic size without appreciably changing their properties. Our theoretical picture of unsteady frictional slip pulses is quantitatively supported by large-scale, dynamic boundary-integral method simulations.

DOI: 10.1073/pnas.2309374120

Source: https://www.pnas.org/doi/10.1073/pnas.2309374120