在密集的玉米粉悬浮液中发生骨折和放松.
Paul Lilin1, Jean E Elkhoury2, Ivo R Peters3
1Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
PNAS nexus
|January 15, 2024
概括
密集的悬浮物可以从流体过渡到类似固体的状态,影响断裂形成. 将空气注入到玉米粉悬浮液中,揭示了这种剪切阻塞行为如何影响骨折生长和放松动态.
科学领域:
- 类风病学 类风病学 类风病学
- 材料科学 材料科学 材料科学
- 软物质物理学 软物质物理学
背景情况:
- 密集悬浮具有可调节的特性,在流体状和固体状状态之间进行过渡.
- 这种过渡被称为剪切阻塞 (SJ),对于理解压力下的材料行为至关重要.
- 在这种材料中,骨折的形成受其动态质性质的影响.
研究的目的:
- 研究剪切阻塞过渡对密集悬浮中断裂形成的影响.
- 描述玉米悬浮中的空气诱导骨折的生长和放松动态.
- 确定与剪切堵塞相关的关键剪切速率及其在骨折放松中的作用.
主要方法:
- 将空气注入大量密集的玉米粉悬浮液中.
- 利用时间分辨率的X射线放射来可视化不透明材料中的空气入侵.
- 在不同的玉米粉度下分析骨折形态和生长动态.
主要成果:
- 在悬浮中注入空气,呈现不连续的剪切加厚和剪切堵塞,导致骨折形成.
- 在高玉米粉质量分数下,骨折会成长为粗的腔.
- 在较低的质量分数下,骨折放松成光滑的气泡,由于浮力而上升.
- 断裂放松的开始与诱导的剪切速率下降到不连续的剪切加厚的临界剪切速率以下相关.
结论:
- 剪切堵塞状态显著影响密集悬浮中的骨折倾向和形态.
- 观察到的断裂放松提供了剪切阻塞过渡的结构特征.
- 了解这些动态是控制密集粒子系统中材料故障和行为的关键.
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