Binaree Theechalit, Azéma Emilien, Estrada Nicolas, Renouf Mathieu, Preechawuttipong Itthichai
Department of Mechanical Engineering, Faculty of Engineering, Chiang Mai University, 239 Huay Kaew Road, Chiang Mai 50200, Thailand.
LMGC, Université de Montpellier, CNRS, Montpellier, France.
Phys Rev E. 2020 Aug;102(2-1):022901. doi: 10.1103/PhysRevE.102.022901.
We present a systematic numerical investigation concerning the combined effects of sliding friction and particle shape (i.e., angularity) parameters on the shear strength and microstructure of granular packings. Sliding friction at contacts varied from 0 (frictionless particles) to 0.7, and the particles were irregular polygons with an increasing number of sides, ranging from triangles to disks. We find that the effect of local friction on shear strength follows the same trend for all shapes. Strength first increases with local friction and then saturates at a shape-dependent value. In contrast, the effect of angularity varies, depending on the level of sliding friction. For low friction values (i.e., under 0.3), the strength first increases with angularity and then declines for the most angular shapes. For high friction values, strength systematically increases with angularity. At the microscale, we focus on the connectivity and texture of the contact and force networks. In general terms, increasing local friction causes these networks to be less connected and more anisotropic. In contrast, increasing particle angularity may change the network topology in different directions, directly affecting the macroscopic shear strength. These analyses and data constitute a first step toward understanding the joint effect of local variables such as friction and grain shape on the macroscopic rheology of granular systems.
我们针对滑动摩擦和颗粒形状（即棱角度）参数对颗粒填料抗剪强度和微观结构的综合影响展开了系统的数值研究。接触处的滑动摩擦系数从0（无摩擦颗粒）变化到0.7，颗粒为边数不断增加的不规则多边形，范围从三角形到圆盘。我们发现，对于所有形状，局部摩擦对抗剪强度的影响遵循相同趋势。强度首先随局部摩擦增加，然后在一个与形状相关的值处达到饱和。相比之下，棱角度的影响则因滑动摩擦水平而异。对于低摩擦值（即低于0.3），强度首先随棱角度增加，然后对于最尖锐的形状会下降。对于高摩擦值，强度随棱角度系统性增加。在微观尺度上，我们关注接触网络和力网络的连通性及纹理。一般而言，增加局部摩擦会使这些网络的连通性降低且各向异性增强。相比之下，增加颗粒棱角度可能会在不同方向改变网络拓扑结构，直接影响宏观抗剪强度。这些分析和数据是迈向理解诸如摩擦和颗粒形状等局部变量对颗粒系统宏观流变学联合效应的第一步。
