Ultrastable Shear-Jammed Granular Material
Ultrastable Shear-Jammed Granular Material
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DOI：
10.1103/physrevx.12.031021
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发表时间：
2021-05
影响因子：
12.5
通讯作者：
Yiqiu Zhao;Yuchen Zhao;Dong Wang;Hu Zheng;B. Chakraborty;J. Socolar
中科院分区：
文献类型：
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作者：
Yiqiu Zhao;Yuchen Zhao;Dong Wang;Hu Zheng;B. Chakraborty;J. Socolar
干燥的颗粒材料，如沙子、砾石、药丸或农业谷物，在压缩或剪切时会变得坚硬。在各向同性压缩下，材料将达到一定的干扰密度，然后抵抗进一步的压缩。当系统中出现密度低于干扰密度的剪切阻力时，就会发生剪切干扰。尽管剪切干扰在摩擦颗粒材料中普遍存在，但标准弹性理论并不能很好地描述其稳定性能，因此需要进行实验表征。我们报告了小幅度准静态循环剪切作用下剪切堵塞颗粒材料机械性能变化的实验观察结果。我们研究了一层限制在剪切单元中的塑料盘，使用光弹性测量法来测量所有颗粒间矢量力。对于足够小的循环剪切振幅和足够大的初始剪切，材料会演变成意想不到的“超稳定”状态，其中所有颗粒位置和颗粒间接触力在每个完整的剪切循环数千个循环后保持不变。与原始剪切卡住状态相比，这些状态对小施加剪切的应力响应几乎是弹性的。
Dry granular materials such as sand, gravel, pills, or agricultural grains, can become rigid when compressed or sheared. Under isotropic compression, the material will reach a certain jamming density and then resist further compression. Shear jamming occurs when resistance to shear emerges in a system at a density lower than the jamming density. Although shear-jamming is prevalent in frictional granular materials, their stability properties are not well described by standard elasticity theory and thus call for experimental characterization. We report on experimental observations of changes in the mechanical properties of a shear-jammed granular material subjected to small-amplitude, quasi-static cyclic shear. We study a layer of plastic discs confined to a shear cell, using photoelasticimetry to measure all inter-particle vector forces. For sufficiently small cyclic shear amplitudes and large enough initial shear, the material evolves to an unexpected “ultra-stable” state in which all the particle positions and inter-particle contact forces remain unchanged after each complete shear cycle for thousands of cycles. The stress response of these states to small imposed shear is nearly elastic, in contrast to the original shear jammed state.