The Effect of Confinement and Material Heterogeneities on the Dynamics of a Granular Medium Subjected to Impact Loading
The Effect of Confinement and Material Heterogeneities on the Dynamics of a Granular Medium Subjected to Impact Loading
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约束和材料异质性对冲击载荷下颗粒介质动力学的影响
DOI：
10.1016/j.prostr.2022.01.102
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
and D. Xi
中科院分区：
文献类型：
--
作者：
Uenishi;K.;and D. Xi
与已经建立的连续介质力学相比，散粒体的力学特性，特别是动力学特性，还没有完全阐明。因此，在我们以前的初步研究中，动态应力传递以及波和破裂的发展，在粒状介质中已被记录使用的实验技术，结合高速摄影的动态光弹性。利用数字激光切割机制备硬币状颗粒，并将其堆积在刚性水平面上，形成具有一定倾角的模型边坡。二维边坡在其顶部自由表面上受到动力冲击。从实验记录的粒子运动和瞬态应力演化，两个不同的故障模式已被确定。一种是由于单向力链状应力传递导致的边坡完全崩塌或质量流，另一种是由广泛扩展的二维波引起的边坡倾倒式分离。无论发生什么，似乎都是由撞击产生的能量的时间分布决定的。在这里，为了调查的约束和可能的材料异质性对颗粒动力学的影响，首先，实验上，固体板被另外放置在一些边界的模型斜坡。结果表明，附加固体边界在很大程度上控制着约束颗粒介质中的应力传递和动力学运动。然后，为了在数值上证实上述实验观察结果，采用开源代码ESyS-Particle。数值计算结果与实验结果进行了比较，如果所需的参数的数值是仔细和适当的选择。
Compared with the mechanics of continua that has been established well, the mechanical characteristics of granular particles, in particular, the dynamic ones, have not been thoroughly clarified yet. Therefore, in our previous preliminary study, dynamic stress transfer as well as wave and fracture development in granular media has been recorded using the experimental technique of dynamic photoelasticity in conjunction with high-speed cinematography. Penny-shaped particles have been prepared by a digital laser cutter and piled on a rigid horizontal plane to form a model slope with some inclination angle. The two-dimensional slope has been subjected to dynamic impact on its top free surface. From the experimentally recorded particle motion and transient stress evolution, two dissimilar failure patterns have been identified. One is the complete collapse of the slope or mass flow due to unidirectional force-chain-like stress transfer, and the other one is the toppling-type separation of the slope face caused by broadly expanding two-dimensional waves. Whichever occurs seems to be governed by the temporal profile of the energy given by the impact. Here, in order to investigate the effect of confinement and possibly material heterogeneities on granular dynamics, first, experimentally, solid plates are additionally placed on some boundaries of the model slopes. It is found that stress transfer and dynamic motion in the confined granular medium is largely controlled by the additional solid boundaries. Then, in order to numerically confirm the above experimental observations, the open source code ESyS-Particle is employed. The numerical results compare well with the experimental ones if the parameters required for the numerics are carefully and properly selected.