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通过动态阻塞前线,致密悬浮的冲击激活固化
Scott R Waitukaitis1, Heinrich M Jaeger
1James Franck Institute and Department of Physics, The University of Chicago, Chicago, Illinois 60637, USA. swaitukaitis@uchicago.edu
Nature
|July 13, 2012
概括
密悬浮物在轻微扰动时会像液体一样,但在强力下会固化. 这项研究揭示了冲击产生的固化,而不是剪切加厚,解释了它们吸收动量的非凡能力.
科学领域:
- 物理 物理学 物理
- 材料科学 材料科学 材料科学
- 流体动力学 流体动力学
背景情况:
- 密集的颗粒悬浮体呈现剪切加厚,在轻微扰动时表现得像液体,但在强力下凝固.
- 现有的模型将剪切加厚归因于水力动力相互作用或颗粒膨胀,但这些并不能完全解释在冲击下极端正常的应力产生.
研究的目的:
- 为了研究密集颗粒悬浮物异常抗冲击能力背后的物理机制.
- 挑战一种普遍的观点,即剪切加厚仅仅解释了这些非牛顿流体的冲击行为.
主要方法:
- 利用高速录像,嵌入力传感和X射线成像来捕捉撞击动态.
- 研究了一根金属棒撞击玉米粉在水中的悬浮物时的减速.
- 开发了动态固化及其对悬浮行为影响的定量模型.
主要成果:
- 证明撞击会产生固化前线,将粒子矩阵转化为一个堵塞的区域.
- 观察到这种动态固化导致异常的动量吸收,远远超过了在剪切或延伸中看到的极限.
- 用一种新型模型量化复制观察到的撞击行为.
结论:
- 密集悬浮的显著抗冲击能力主要是由于冲击产生的动态固化,而不是剪切加厚.
- 这种现象造成了快速增长的堵塞区域,使得动量有显著的消散.
- 修订了对密集颗粒悬浮物冲击阻力的理解,突出了独特的固化机制.
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