Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Phys Rev E. 2018 Jan;97(1-1):012904. doi: 10.1103/PhysRevE.97.012904.
We probe the effects of particle shape on the global and local behavior of a two-dimensional granular pillar, acting as a proxy for a disordered solid, under uniaxial compression. This geometry allows for direct measurement of global material response, as well as tracking of all individual particle trajectories. In general, drawing connections between local structure and local dynamics can be challenging in amorphous materials due to lower precision of atomic positions, so this study aims to elucidate such connections. We vary local interactions by using three different particle shapes: discrete circular grains (monomers), pairs of grains bonded together (dimers), and groups of three bonded in a triangle (trimers). We find that dimers substantially strengthen the pillar and the degree of this effect is determined by orientational order in the initial condition. In addition, while the three particle shapes form void regions at distinct rates, we find that anisotropies in the local amorphous structure remain robust through the definition of a metric that quantifies packing anisotropy. Finally, we highlight connections between local deformation rates and local structure.
我们探究了颗粒形状对二维颗粒柱（作为无序固体的代理）在单轴压缩下的整体和局部行为的影响。这种几何形状允许直接测量整体材料响应，以及跟踪所有单个颗粒轨迹。一般来说，由于原子位置的精度较低，在非晶材料中很难建立局部结构和局部动力学之间的联系，因此本研究旨在阐明这种联系。我们通过使用三种不同的颗粒形状来改变局部相互作用：离散的圆形颗粒（单体）、连接在一起的颗粒对（二聚体）和以三角形连接的三个颗粒组（三聚体）。我们发现二聚体显著增强了柱子，这种效果的程度取决于初始条件下的取向有序性。此外，虽然这三种颗粒形状以不同的速率形成空隙区域，但我们发现通过定义一个量化堆积各向异性的度量标准，可以使局部非晶结构的各向异性保持稳健。最后，我们强调了局部变形率和局部结构之间的联系。
