Recent studies have demonstrated that amorphous materials, from granular packings to atomic glasses, share multiple striking similarities, including a universal onset strain level for yield. This is despite vast differences in length scales and in the constituent particles’ interactions. However, the nature of localized particle rearrangements is not well understood, and how local interactions affect overall performance remains unknown. Here, we introduce a multiscale adhesive discrete element method to simulate recent novel experiments of disordered nanoparticle packings indented and imaged with single nanoparticle resolution. The simulations exhibit multiple behaviors matching the experiments. By directly monitoring spatial rearrangements and interparticle bonding/debonding under the packing’s surface, we uncover the mechanisms of the yielding and hardening phenomena observed in experiments. Interparticle friction and adhesion synergistically toughen the packings and retard plastic deformation. Moreover, plasticity can result from bond switching without particle rearrangements. These results furnish insights for understanding yielding in amorphous materials generally.

中文翻译：

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摩擦和粘附控制无序纳米颗粒填料的产量：多尺度粘附离散元方法研究

最近的研究表明，从颗粒状填料到原子玻璃，无定形材料具有多个惊人的相似之处，包括通用的屈服起始应变水平。尽管长度尺度和组成粒子的相互作用存在巨大差异。然而，局部粒子重排的性质尚不清楚，局部相互作用如何影响整体性能仍然未知。在这里，我们引入了一种多尺度粘合剂离散元方法来模拟最近的无序纳米颗粒堆积的新实验，该实验以单个纳米颗粒分辨率进行缩进和成像。模拟表现出与实验相匹配的多种行为。通过直接监测填料表面下的空间重排和颗粒间结合/脱粘，我们揭示了实验中观察到的屈服和硬化现象的机制。颗粒间摩擦和粘附协同增韧填料并阻止塑性变形。此外，可塑性可以由没有粒子重排的键转换产生。这些结果为理解一般无定形材料的屈服提供了见解。