Abstract

Realistic yet efficient representation of particle shape is a major challenge for the Discrete Element Method. This paper uses angle-of-repose and direct-shear test simulations to describe the influence of several shape representation methods, and their parameters, on the bulk response of granular assemblies. Three rolling resistance models, with varying coefficient of rolling friction, are considered for spherical particles. For non-spherical particles, superquadrics with varying blockiness and multi-spheres with varying bumpiness are used to model cuboids and cylinders of several aspect ratios. We present extensive quantitative results showing how the various ways used to represent shape affect the bulk response, allowing comparisons between different approaches. Simulations of angle-of-repose tests show that all three rolling friction models can model the avalanching characteristics of cube/cuboid and cylindrical particles. Simulations of direct-shear tests suggest that both the shear strength and the dilative response of the considered non-spherical particles (but not their porosity) can only be predicted by the elasto-plastic rolling resistance model. The quantitative nature of the results allows identifying values of the shape-description parameters that can be used to obtain similar results when using alternative shape representation methods.

Graphical abstract

中文翻译：

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各种DEM形状表示方法对颗粒组件的堆积和剪切的影响

摘要

离散形状方法的现实挑战是有效表达颗粒形状，这是一项重大挑战。本文使用休止角和直接剪切试验模拟来描述几种形状表示方法及其参数对颗粒组件的整体响应的影响。对于球形颗粒，考虑了三种具有不同滚动摩擦系数的滚动阻力模型。对于非球形粒子，具有变化的块状度的超二次方和具有变化的凸度的多球体用于模拟长宽比不同的长方体和圆柱体。我们提供了广泛的定量结果，这些结果显示了用来表示形状的各种方式如何影响体积响应，从而可以在不同方法之间进行比较。休止角测试的仿真表明，所有三个滚动摩擦模型都可以对立方体/立方体和圆柱颗粒的雪崩特性进行建模。直接剪切试验的模拟表明，只能通过弹塑性滚动阻力模型来预测所考虑的非球形颗粒的剪切强度和膨胀响应（但不能评估其孔隙率）。结果的定量性质允许识别形状描述参数的值，当使用替代的形状表示方法时，该值可用于获得相似的结果。直接剪切试验的模拟表明，只能通过弹塑性滚动阻力模型来预测所考虑的非球形颗粒的剪切强度和膨胀响应（但不能评估其孔隙率）。结果的定量性质允许识别形状描述参数的值，当使用替代的形状表示方法时，该值可用于获得相似的结果。直接剪切试验的模拟表明，只能通过弹塑性滚动阻力模型来预测所考虑的非球形颗粒的剪切强度和膨胀响应（但不能评估其孔隙率）。结果的定量性质允许识别形状描述参数的值，当使用替代的形状表示方法时，该值可用于获得相似的结果。

图形概要