AI 中文总结
本研究揭示循环驱动非晶固体屈服时的不可逆性源于近简并塑性不稳定性竞争导致的轨迹分支，而非混沌动力学，平均场软点模型重现了该分支统计并明确其微观起源。
AI 中文摘要
经受无热准静态振荡剪切的非晶固体在屈服时会从周期性可逆动力学转变为不可逆扩散动力学。在这种确定性耗散动力学中，不可逆性如何产生仍不清楚。本文表明，即使在不可逆区域，轨迹仍保持局部稳定，扰动会衰减而非增长，排除了与混沌动力学相关的对初始条件的持续指数敏感性。附近轨迹并非持续发散，而是最初保持接近，之后通过罕见的分支事件分离，分离后扩散式增长。平均场软点模型重现了相同的分支统计并揭示了其微观起源。研究发现，分支源于近简并塑性不稳定性之间的竞争，微小扰动会改变哪个不稳定性先激活，进而改变后续塑性事件序列。这些结果确定了由不稳定性选择诱导的分支是循环驱动非晶固体不可逆性的动力学机制。
英文摘要
Amorphous solids subjected to athermal quasistatic oscillatory shear undergo a transition from periodic reversible dynamics to irreversible diffusive dynamics at yielding. How irreversibility arises in such deterministic, strongly dissipative systems remains unclear. Here we directly test the proposal that post-yield irreversibility originates from chaotic dynamics and exponential sensitivity to initial conditions. Contrary to this interpretation, perturbations initially contract rather than grow, even in the irreversible regime, with nearby trajectories remaining close for extended periods. Separation occurs only through rare branching events, after which the distance grows diffusively at the rate expected for independent trajectories. The waiting times to branching are exponentially distributed, defining a steady-state branching rate that vanishes in trained reversible limit cycles and becomes finite above yielding. A mean-field soft-spot model reproduces these branching statistics and reveals their microscopic origin: a small perturbation can reverse the activation order of two nearly degenerate plastic instabilities, altering the subsequent sequence of plastic events. These results show how local stability and global irreversibility can coexist in a dissipative many-body system and identify instability-selection-induced branching as a distinct dynamical route to irreversibility in driven amorphous solids.
