Hybrid discrete-continuum modeling of shear localization in granular media
Hybrid discrete-continuum modeling of shear localization in granular media
复制标题
DOI：
10.1016/j.jmps.2021.104404
复制
发表时间：
2021-03
影响因子：
5.3
通讯作者：
Peter Yichen Chen;Maytee Chantharayukhonthorn;Yonghao Yue;E. Grinspun;K. Kamrin
中科院分区：
文献类型：
--
作者：
Peter Yichen Chen;Maytee Chantharayukhonthorn;Yonghao Yue;E. Grinspun;K. Kamrin
剪切局部化是颗粒材料的一种常见特征。虽然离散元方法可以很好地模拟这种现象，只要颗粒表示是准确的，但当颗粒数量较多时，计算起来就困难了。基于连续介质的有限元方法在计算上是容易处理的，但由于网格依赖，除非本构模型具有长度尺度，否则很难捕捉许多颗粒尺度的影响，例如剪切带厚度。我们提出了一种混合离散-连续介质技术，它结合了连续介质方法的速度和离散方法的粒度精度。在剪切局部化问题的情况下，我们使用基于连续介质的材料点法开始模拟。随着模拟的发展，我们监控一个适应预言来识别剪切带的开始，并使用离散元方法将宏观连续剪切带忠实地丰富到微观尺度的颗粒中。然后，我们的算法用离散方法模拟剪切带区域，同时继续用连续方法模拟区域的其余部分，因此计算成本仍然比纯离散解低得多。我们在干燥和粘性颗粒介质的平面剪切、三轴压缩和平板压痕试验中验证了我们的技术。我们的方法与纯离散模拟一样准确，但比需要数千万颗粒的离散模拟快100倍以上。
Shear localization is a frequent feature of granular materials. While the discrete element method can properly simulate such a phenomenon as long as the grain representation is accurate, it is computationally intractable when there are a large number of grains. The continuum-based finite element method is computationally tractable, yet struggles to capture many grain-scale effects, e.g., shear band thickness, because of mesh dependence, unless the constitutive model has a length scale. We propose a hybrid discrete-continuum technique that combines the speed of the continuum method with the grain-scale accuracy of the discrete method. In the case of shear localization problems, we start the simulation using the continuum-based material point method. As the simulation evolves, we monitor an adaptation oracle to identify the onset of shear bands and faithfully enrich the macroscopic continuum shear bands into the microscopic-scale grains using the discrete element method. Our algorithm then simulates the shear band region with the discrete method while continuing to simulate the rest of the domain with the continuum method so that the computational cost remains significantly cheaper than a purely discrete solution. We validate our technique in planar shear, triaxial compression, and plate indentation tests for both dry and cohesive granular media. Our method is as accurate as a purely discrete simulation but over 100 times faster than a discrete simulation that would require tens of millions of grains.