Saitoh Kuniyasu, Oyama Norihiro, Ogushi Fumiko, Luding Stefan
Research Alliance Center for Mathematical Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
WPI-Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
Soft Matter. 2019 Apr 24;15(17):3487-3492. doi: 10.1039/c8sm01966e.
We study slip-avalanches in two-dimensional soft athermal disks by quasi-static simulations of simple shear deformations. Sharp drops in shear stress, or slip-avalanches, are observed intermittently during steady state. Such stress drops are caused by restructuring of the contact networks, accompanied by drastic changes of the interaction forces, Δf. The changes of the forces happen heterogeneously in space, indicating that collective non-affine motions of the disks are most pronounced when slip-avalanches occur. We analyze and predict the statistics for the force changes, Δf, by transition rates of the contact forces and angles, where slip-avalanches are characterized by wide power-law tails. We find that the transition rates are described by a q-Gaussian distribution regardless of the area fraction of the disks. Because the transition rates quantify structural changes of the force-chains, our findings are an important step towards linking macroscopic observations to a microscopic theory of slip-avalanches in the experimentally accessible quasi-static regime.
我们通过简单剪切变形的准静态模拟研究二维软无热盘体中的滑移雪崩现象。在稳态过程中，间歇性地观察到剪切应力的急剧下降，即滑移雪崩。这种应力下降是由接触网络的重构引起的，同时伴随着相互作用力Δf的剧烈变化。力的变化在空间上是不均匀发生的，这表明当发生滑移雪崩时，盘体的集体非仿射运动最为显著。我们通过接触力和角度的跃迁率来分析和预测力的变化Δf的统计数据，其中滑移雪崩的特征是具有宽幂律尾部。我们发现，无论盘体的面积分数如何，跃迁率都由q-高斯分布描述。由于跃迁率量化了力链的结构变化，我们研究结果是在实验可及的准静态状态下，将宏观观测与滑移雪崩微观理论联系起来的重要一步。
