倾斜低速撞击角粒状介质时的次表面粒状动力学
Sub-surface granular dynamics in the context of oblique, low-velocity impacts into angular granular media
摘要：
在太空探索过程中，对地外地形的倾斜、低速撞击是不可避免的。我们进行了二维离散模拟模型的三角形颗粒床的影响。有限元法为模拟提供了基础，实现了有角晶粒的几何形状。我们的研究结果重新创建了以前从实验中注意到的三类碰撞行为：完全停止，滚动和跳弹\citep*{Wright2020}。集合Voronoi曲面细分的应用以高分辨率评估填充分数，揭示颗粒在撞击事件期间如何相对于彼此移动。冯米塞斯应变分布的计算，然后揭示了如何相对于整个系统的晶粒转移，导致的“皮肤区”的概念。直觉表明，扰动晶粒的区域将随着更高的速度影响而变深，结果反而表明，增加速度实际上可能引起晶粒耗散响应的变化，从而增强横向扰动。最后，我们认为，作为一个整体，如何子表面的响应可以与撞击动力学，以加深我们的理解斜，低速的影响事件，并帮助改善任务的成果。
英文摘要：
Oblique, low-velocity impacts onto extraterrestrial terrain are an inevitable occurrence during space exploration. We conduct two-dimensional discrete simulations to model such impacts into a bed of triangular grains. Finite element method provides the basis for simulation, enabling the angular grain geometry. Our findings re-create the three classes of impact behavior previously noted from experiments: full-stop, rollout, and ricochet \citep*{Wright2020}. An application of Set Voronoi tessellation assesses packing fraction at a high resolution, revealing how grains shift relative to each other during an impact event. Calculation of Von Mises strain distributions then reveal how grains shift relative to the overall system, leading to the notion of the 'skin zone'. Intuition would suggest that the region of perturbed grains would grow deeper with higher velocity impacts, results instead show that increasing velocity may actually evoke a change in the grains' dissipative response that boosts lateral perturbation. Finally, we consider as a whole how sub-surface response could link with impactor dynamics to deepen our understanding of oblique, low-velocity impact events and help to improve mission outcomes.
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