发表机构
Tata Institute of Fundamental Research（塔塔基础研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究人员通过分子动力学模拟发现，活性会降低玻璃的动力学脆弱性，改变其屈服力学响应，确立了动力学脆弱性是控制被动与活性玻璃屈服的统一参数，为调控非晶材料力学响应提供了新途径。
AI 中文摘要
屈服转变标志着非晶固体中不可逆塑性变形的起始，在决定金属玻璃、胶体悬浮液和生物组装体的力学稳定性与失效方面发挥核心作用。尽管已有大量研究，但控制屈服性质的微观因素，尤其是脆性与延性力学响应之间的转变，仍鲜为人知。近期研究已确认动力学脆弱性是控制被动玻璃屈服的关键参数，而该关联是否在活性玻璃中依然成立尚不清楚。本文通过对掺杂有跑- tumble（RTP）活性粒子的Kob-Andersen玻璃形成体在振荡剪切下进行分子动力学模拟，结果显示：活性会系统性降低动力学脆弱性，进而改变力学响应；共同屈服点γ_c随活性单调递减，且对Arrhenius活化势垒呈现幂律依赖关系；增加活性会抑制屈服应变对热历史的依赖，并将响应从类脆性转变为日益延性，表现为应力弛豫更平滑、应力不连续性减少；屈服附近达到稳态的时间尺度仍保持临界幂律发散，表明活性并未改变转变的潜在临界性质；活性玻璃还会形成更宽、更弥散的剪切带。本研究确立了动力学脆弱性为控制被动与活性玻璃屈服的统一参数，并证明活性为调控非晶材料的力学响应提供了有效途径。
英文摘要
The yielding transition marks the onset of irreversible plastic deformation in amorphous solids and plays a central role in determining the mechanical stability and failure of metallic glasses, colloidal suspensions, and biological assemblies. Despite extensive research, the microscopic factors governing the nature of yielding, particularly the transition between brittle and ductile mechanical responses, remain poorly understood. Recent studies have identified kinetic fragility as a key parameter governing yielding in passive glasses; whether this connection persists in active glasses remains open. Here, using molecular dynamics simulations of a Kob-Andersen glass former doped with Run-and-Tumble (RTP) active particles under oscillatory shear, we show that activity systematically reduces kinetic fragility and consequently alters the mechanical response. The common yield point $γ_c$ decreases monotonically with activity and exhibits a power-law dependence on the Arrhenius activation barrier. Increasing activity suppresses the dependence of the yield strain on thermal history and transforms the response from brittle-like to increasingly ductile, with smoother stress relaxation and reduced stress discontinuities. The timescale to reach steady state near yielding retains a critical power-law divergence, indicating that activity does not alter the underlying critical character of the transition. Active glasses also develop broader, more diffuse shear bands. Our results establish kinetic fragility as a unifying parameter governing yielding in both passive and active glasses and demonstrate that activity offers a powerful route to tune the mechanical response of amorphous materials.
Comments19 pages, 11 figures
